rudder discussions

I was looking for those horizontal slats, but assume CPete took the picture at an angle, and, if rotated to be viewed properly, the bow facing toward the sky, the spaces between the slats would be horizontal. I assume CPete that such is what you were referring to when referring to horizontal slats. Right?

My original rudder looked similar to CPete's, and, like it, the slats had separated/shrunk (not good). The bolts went through to the center of the center slat as I recall. The propeller insert (for the outboard version) was held in place by a couple small angular screws from the wood rudder to the wood insert.

It might be interesting to associate a year with the boats we are referencing so we could get a take on if, and the extent to which the design changed over time.

As I have said in previous rudder related threads, I'm getting all of the materials together so that I can really get to work next fall and build a new rudder.
Things a really falling into place pretty well. I was really considering "Jamestown Distributors" for the 1" rod except that it is silicone bronze. This past week I found another supplier near Chicago called "Copper and Brass Sales" in Schaumburg, Il. phone: 800-926-2600. They have true "464 Naval Bronze rod" and it is $50.00 cheaper than J.D. for the approx. 6 foot length that we need for a Ariel shaft, or $148.43 for 6 foot of 1". They also have many other rod sizes and I think I'm going to use their 5/16 " naval rod from blind holes through the planks. Just thought I'd pass this info along.
__________________________________________________ __
I still am looking for companies which sell Hondouran Mahogany if anyone knows of any. Jim_______________________________________________ ___

Jim:

There are two places you might want to look at. One is Kettle Morain Hardwoods - with a place on 94 just south of Milwaukee (Racine area) and one just north of Milwaukee. The town is Caledonia and the phone is 835-9212 (Don't know the area code but it might be 262). They are very helpful - good people - and they like sailors.

There is/was a place in Bedford Park, just south of Chicago, that handles specialty woods. I used to deal with them but now have found the first place, closer to home.

Jim,

You might try Pekin Hardwoods S. Main St in Bloomington. Their yard is just south of Pekin, but they have the retail store in Bloomington and can get most anything you need. Nice folks there...just don't ask for marine ply, unless you like blank looks.

Probably should keep my mouth shut.

Naval bronze is naval brass and can have as much as 40% zinc to 59% copper, with a bit of tin as a binder. Better ask for the alloy numbers from the supplier. And I would get the alloys closer together on the galvanic scale viz the shoe/shaft and aft thruhulls. But then that's just my opinion.

Theis, Greg, and Ebb;
Thanks to all of you for the help and ideas onthe wood suppliers and the bronze! Bloomington is close to me so I'll run up and have a look. I'll write or call Kettle Morain and the Caledonia Co. and Pekin.
Ebb, you're input is valued, I appreciate your thoughts and I will take heed! I only want to do this rudder once and as correct as possible. I will be wary since I know they will sell you anything just to make the sale. Such are the times in which we live! I have a good sailor friend that is a metallurgist so I'll get the assay and run it by him.
Jim

Jim:

Kettle Morrain Hardwoods is in Caledonia, WI. There is no Caledonia company that I am aware of. Good Luck!

Thanks Capt Jim,
Pearson didn't get it too wrong in the beginning. The class here went through this and discovered that manganese bronze was used for nearly all the cast fittings and the shaft. The stuff is expensive, but that is relative. The dynamic shaft/shoe combo lasted nigh onto 40 years until we came along to refurbish.

Have to amend this. So I looked it up:
manganese b....... Naval brass ......... Everdur
58.5 copper.........60 copper.......... 98.25 copper
39.25 zinc...........39.25 zinc..............0
1 tin..................75 tin...................0
.25 manganese.... 0..........................25
1 iron..................0.........................0
0.........................0....................... ..1.50 silicon

Tensile strength psi of rod.: Hard and soft:

m.b. 45,000 - 30,000. n.b. 63,000 - 56.000. Ev 70.000 - 40.000.

Looks like manganese and naval are just about the same. Well, alloying is still a mystery to me. I went with Everdur. Awhile ago I had an animated discussion with Roger at Bristol Bronze. He stongly supported his highly alloyed manganese, which. he said, Bristol had originally supplied Pearson for the A/Cs, including the shaft.:o

Ebb, Thanks for the comparative assay on manganese and naval; boy they really are close; are you saying that Bristol Bronze has manganese rod in the sizes that we need: One Inch and 5/16's?
Theis, Thanks so much for the corrected address on Kettle Morain.
Jim

This should be filed somewhere readily available by anyone contemplating rebuilding the ruddershoe or shaft. It will be useful before you are done. I'm making it an appendix to the manual and giving a copy to my mold maker. Thanks for the info and effort.
A while ago I did some searches for manganese bronze and naval bronze and turned up a couple sites that seemed to have rod in every size and alloy known to man so anyone looking for rod could consider that route. I'm waiting until I know the exact alloy of the new shoe and then matching that
for the ruddershaft and drift pins.

Tom

Ebb

That is great information. Thanks. But you choosed Everdur, Roger prefers Manganese Bronze, and I assume the reason for the name Naval Brass is because it is for the Navy (as contrasted with an area of the body).

Your information raises the questions Why did you choose Ererdur, Why does the Navy prefer Naval Brass, and why does Roger prefer Manganese Bronze? I understand hardness is one reason.

What about the corrosion element/electrolysis of the compounds? Is it that one is a new and improved version of an earlier type? Can they all be machined by the average machinist? What about cost? As a point of reference, last year we discussed electrolysis and the need to have multiple anodes. Is there a linkage between electrolysis/anodes and manganese bronze - whereas corrosion is less of a problem with the other two compounds?

As for the mystery of compounds and mixtures, it is truly wondrous how a little of this or a little of that can change the properties of something - like adding a teaspoon of cayenne peppers to a bowl of otherwise edible spaghetti.

Manganese bronze rod is available in all sizes. If you are going to make a traditional rudder, I would match the internal rods. too. The problem is getting the alloy only in the length you need, because it is sold in 6 and 12 foot lenghs. or however the supplier deals it from the foundry. [I have a couple of two foot pieces of 1" Everdur left over from my ruddershaft adventure that cost the price of gold, are two precious to get rid of, are too short to do anything with.]

I went with Everdur because I had already cast 338s new shoe in silicon.
I had reasoned with self that silicon is commonly available and that it was likely that any bronze in the water would be silicone.

I then found that B.B. would do castings to patterns I made.. Very cool. Roger is, IMCO, committed to manganese for static load fittings. My discussion with him, which was 95% listening, about my underwater choice in bronze, was when he came up with that manganese would last 100 years but silicon only 50. Bristol has made all the highend jewelry for all the great highend yachts forever. And that Bristol will suffer a fool like me makes Roger close to god. But m.b. over time disintergrates in modern salt water. I think we two ended with a stalemate.

I'm a 'doubting thomas.' There is no doubt that in water fittings on the A/Cs have a problem (in salt water and in marinas..) My reasoning is simple: there isn't enough other ingredients in silicon bronze to leach out and crumble the fitting. Which has happened with our boats, right? Manganese is the best bronze alloy for fittings under load above the waterline.

B.B. might be a source for m. rod. I think his prices are highend but fair. I would check local suppliers.

Bristol Bronze is very committed to resupplying his firms original fittings that Pearson used. But the original molds got lost and a pattern maker has not appeared to make authentic copys. If 338's shoe mold is succesful I'll donate it to the ACA or give it to Roger. [by the way for the nth time - Bristol also has a beefed up version of the 338's stem fitting (in m.b.) that I know he has sold to one Triton owner who was happy with it. I don't know how much. He cosiders the molds you send him as 'public domain.'

I think the crucial observation is that no matter which alloy is chosen it will in all likelihood outlast the chooser. I've wondered if Pearson was as concerned as we have become. My guess is they called for naval bronze because that is what was most readily available at the time and it had been proven to work for centuries. But I've also found that naval bronze means different things to different people and wouldn't be surprised if Pearson left the mixture to the foundry. In the early 1960's the simplest solution would probably have been the most likely and using special alloys that weren't absolutely neccessary would have been unlikely.


Tom

Good information. Thanks. You know, after everthing is taken into account, fresh water sailing is so easy - all we have to do is worry about ice, sleet, snow, shallow water and howlers. None of this corrosion stuff (Unless your boat is wintered next to a chemical factory on the south side of Chicago) and hurricane intimidation.

I rebuilt my Commander rudder useing the original shafts. A blow
by blow account can be found in the archives in Jim Wiles-
"Let's talk rudders" thread. I built this trouble free(6 years and counting)
rudder for about three hundred dollars and a lot of head scratching,
without having to raise the boat. Check it out.
Cheers,B.
Commander#215

On Hustler (Ariel #223), we replaced the rudder 2 times. The first time, we duplicated the original. We lost that rudder in medium air with the chute up. The second replacement was made from aluminum (may have been stainless-my brother-in-law handled getting it done) with the shaft and rudder welded together. This was done in 1994-1995 and is still holding together nicely. Designed the rudder to be narrower, not as tall, but a good 3 inches longer. Made the boat handle much better and took a lot of weight out of the back of the boat.

Has anyone found a supplier for a exact replacement rudder head fitting?
I think that I have wear in the keyway that I would like to eliminate this season with the old rudder and defintely next season with the new rudder.
Jim

That's one of those parts for which Rostand has the pattern. Still waiting for the patterns to be donated . . .

Keyway can be shimmed with paper thin brass sheet.

Bill, My appologies, I should have remembered the posting speaking to the subject of Rostand.
The thin brass sheeting is a good idea to shim with. I'll keep that in mind. Also, a good source for that kind of thing ( thin brass, stainless, etc.) is model railroad scratchbuilding shops!
Another thing that I'm going to do is to mic both sides of my keyway; one side or the other could have worn out of tolerance and what I'm thinking of having done is to have some key stock specially machined to the measurements.
Thanks, Jim

Of course, I cannot find the part laying around anywhere right now (and I did look a bit recently)...but I found a replacement head fitting for another guy's Triton in one of the area seajunk stores not too long ago...the part was cosmetically a bit different, but it worked fine on his boat. These parts were a pretty common size for the type of rudder setup, which was pretty common once upon a time. Might look around that way, too--I think it was less than 50 bucks for a real nice rudder head and the tiller fork to go with it.

Dave

Dave,
Thanks for the tip on the reclamation stores. I'll make a mental note of that. There are three or so of these stores that I have visited in the past in Michigan, Fla., Alabama. Aa I recall I did have good luck there!
Jim

To Everyone interested in rudders,
We finally have all of our rudder materials and we are actually building a RUDDER! Really though, everything was fairly easy to find, was shipped fast, I drove after the mahogany, and really not badly priced. The bronze is really beautiful, the wood is really dense, solid and smells really good.
Will keep you posted and possibly post some pics.
Jim

The rudder is looking great. I had a custom milling company actually do the wooden rudder blades ( I made two for $190.)
They really fit the 1" shaft like a glove. Will post some pics soon
I took them with me to our marina to show my friends and they fell in love with them.

One question for the group: quite a few of my friends thought that I should somehow seal the new mahogany. What do you all think?
Thanks,
Jim

Absolutely you should seal it and seal it and seal it. Apply VERY liberally. The mahogany takes it like a sponge. Both Pettit and Interlux make a clear sealer tha soaks in. It is easy to apply and soaks right in. Use the sealer, not just a thinned down varnish.

Sealing is particularly true in fresh water, as I recall being told, because Mahogany does not have the resistance to rot as it does in salt water. Also, you don't want the additional weight of the waterlogged rudder draging down the stern.

Jim: what style of rudder did you go for? the original heart shaped, or the "Constellation" style shown in the lines in phantom?

Also, what method of attachment are you using? welded plate along the back of the shaft or the original edge-bolted style?

much grass.

Hey, I have posted the question of coatings at

http://www.boatbuilding.com/cgi-bin/...cgi?read=11364

My understanding of bouyancy of the rudder is that neutral bouyancy - watterlogged wood - is best. Therefore, I was not considering any coating other than the porous bottom paint.

The participants at the above forum were very helpful and knowledgeable regarding wood boat construction and my previous posting regarding species was invaluable.

http://media5.hypernet.com/cgi-bin/U...?ubb=get_topic;f=1;t=008475

Now I just have to find the weekday-time to get to Condon's in White Plains to pick out the suitably-grained plank. Though they will ship, they would not guarantee they would be able to pick the "right" grain for my demanding project.

Hi everyone and thanks so much for your input. I built the original rudder shape which I have used for 25 years. We are using the continuous shaft from head to shoe and drilling 1/2" blind holes in shaft for five 3/8" bronze rods which will exit aft rudder. Should be very stout. Rods will be tig tacked to shaft following being screwed into the holes so that they cannot loosen. Lock nuts and suitable sized washers will be used on the rod ends. Will fair the aft rudder edge following the first season of immersion. Should fair very nicely.
Thanks for the web site dealing with toseal or not to seal.
Hope to shoot some digital pics today to post here.
Jim

p.s. Commanderpete's drawing and measurements of his old Commander rudder were right on the mark and helped me a great deal. I thank him so much for his time and effort.
I measured my bronze rudder shaft with a fish tape vicegripped to the top of the shaft and through the rudder tube and measured to the top of the bearing surface on the rudder shoe, and certainly added the length of the boss to the total.

Finally got everything together and got the new rudder/shaft/shoe on the boat. Everything fit, it works wonderfully and I'm a happy camper.
Some observations from the project
1) Also had some keel heel disintegration once I got the old shoe off. Not as bad as Bill Hoover's but of the four ruddershoe bolts only two were anchored in something solid. Kind of scary and you can't tell unless you take the ruddershoe off. Might be worth considering as a potential maintenance problem.
2) The rudder shoe Fred Pomeranz built fit beautifully. It's a little wide at the front end (about 1/8" on either side on the front edge) but that was easy to fair out. Could also have ground down the excess without affecting the strength of the casting. It's substantial, considerably more so than what was on there.
3) The old shoe was silicone bronze. Having seen what happens to silicone bronze over time, I'm glad I went with manganese. The old shoe and shaft were so worn that the rudder shaft/shoe fitting was totally deformed. I also found that although the metal had a nice bronze color when I scraped it when I hit it with a hammer while driving the pins out it fractured because the metal was so crystallized. Once I had it off I could flex the sides of the shoe inward just by squeezing. Not my idea of solid. I'm also relatively certain the old shoe was not original. It had been amatuerishly faired with a filler that was easy to remove and when it was out it was easy to see where the original ruddershoe had been and much to my delight the new shoe fit there almost perfectly.
4) I went with a solid manganese shaft with five drift pins to attach the rudder to and this baby is also substantial. There is something to be said for knowing your rudder is a bit overbuilt. (if you're not a racer) Used a slightly different technique for the rudder boards- instead of using 2 2X10 mahogany planks I used 1X10's and face epoxied (and screwed) them together after I routed grooves in both sides to fit the drift pins. Didn't have the drilling equipment to drill true, accurate holes in the 2X and doing it this way worked well. Also figured that having opposing grains on either side would help lessen the tendency to warp. Will see how it worked next haulout.

After I got it together I took the boat for a spin around the harbor to make sure it worked then took off the next day for a three week trip up the east coast of Vancouver Island. Probably wasn't the smartest thing to take off with an untested rudder but I felt confident, knowing how much more sound the rudder assembly was than it had been, and I didn't have any problems, and ran into some serious wind and waves along the way. I must say it's a lot more fun using a rudder than installing one.

My thanks to everyone who offered help, advice, observations through the project. Your input was invaluable and it wouldn't have come out as well without it.

Happy sailing,
Tom
Tom

Congratulations Tom Tom,
Let me say this:
The first important thing is to get all your bronzes the same alloy.
I believe that will go a long way to keep corrosion at bay yOU HAVE DONE THAT WITH YOUR SHAFT AND SHOE..

The second important thing is that there is nothing wrong with silicon bronze, for the same reason as above. In fact there is LESS to leach out, in a hot marina say, than manganese. Besides I chose silicone. And a good reason for that is: the other components in the rudder: allthread. rod and bolts, even thruhulls are impossible to find in manganese.

Third, as you state in your post your FORMER bronze shoe was of an alloy that disintegrated, AND readers should respond to your graphic detail of the rudder shoe's FINAL DEMISE!

I don't believe you can assume the former DFO's rudder shoe was SILICON BRONZE! WHY do you think so???
IMCO the shoe was cast in NAVAL BRONZE, which is actually brass, which has enuf zinc in it to be a back up battery. What you describe is major dezincing, which could NOT happen to silicon bronze. Never use naval bronze. Simple statement. It is the truth.

In fact I think what you have witnessed here is an empiracal example of the WRONG alloy to use in a the Ariel rudder shoe, especialy if you have chosen a dissimular alloy for your rudder shaft.

Now, of course you have silicon bronze hiding in the blade of your restoration......we shall see, we shall see. Manganese is NOT the more noble bronze here! Silicon is! Even WINIARSKI can't deny that. Did you use m. bronze for the pins?
On 388 I used all s. bronze. Yet I got signs of a reaction when captured water passed thru the laminated the shoe is attached to and out a couple of the holes the pins were peened over on.

Manganese bronze is actually a brass. Some of these alloys have as much as 40% zinc in them. They are rated as corrosion resistant. As we know the right combination of unpredictable galvanic circumstances and the cookie crumbles. The right combination may never befall you. Bristol Bronze said they supplied the original Pearson Ariels with manganese shaft and shoe. AND THEY LASTED AS LONG AS THEY DID.
Your former disintegrated could very well have been manganese bronze.
Assume is the mother of all f...ups!

Ebb,
I think you are probably right about the old shoe being naval, not silicone bronze. Electrolysis wise it makes more sense and the old shoe was definitely missing some molecules of something. That being said, I'd still go with manganese. It has a higher tensile strength and is considerably harder and after seeing the wear the old shaft put into the shoe I like the idea of a harder bearing surface. As to having silicone bronze inside the blade, the only silicone I used were the nuts, which are now encased in an inch of epoxy and pretty well isolated. As you so accurately point out, manganese bronze nuts and other parts don't exist so I had to use silicone. The rods are manganese bronze cut to length and threaded on both ends and the pins for mounting the shoe are manganese rod peened and ground off so it's all pretty much the same alloy, which is the key, regardless of which you choose. And even with matching alloys I've become a big believer in zincs.

Tom

I know a little bit about rudders--at least enough to point me toward the right marina bar with the right woman in tow. Whether she is of a silicone construction or not is a matter of little import at best. But I do like 'em brassy. Whadda you two zinc?

I have a pearson commander (late 1960's) the old wooden rudder is finally dead.

I need help and information that will lead to a replacement.

Any thoughts


Bernard A. Kravitz
bakravit (A) comcast.net

The rudder on my (alas) former Commander was simply a few pieces of mahogany glued/bolted together with appropriate holes for drift pins and attachments. If yours is still good enough to make a pattern and the metal pieces are intact, it is not a big job from a woodworking point of view. Or I guess you could use thickened epoxy and fiberglass and encapsulate the existing rudder.

As Bill always reminds us, using the search button will turn up more advice on a given subject than most people can assimilate in one sitting.

Happy New Year to all!

Al Lorman

Thanks Al ;)

I have decided that since my rudder is probably original, I'm just going to completely rebuild it, sticking pretty close to the original design, except I agree with EBB and have decided to use Silicone Bronze 655 throughout. The shoe is my only concern, perhaps I will use a zinc there or are there silicon bronze repros available? Or should I worry about it?
I got a quote from Alaska Metals in Seattle (I was a little put off by their misleading name) of $111 for a 6ft length of 1" rod, sounded like an OK price.
Also got a quote from Edensaw in Port Townsend for $6.73/bf for 4/4 Honduras Mahogany for the rudder itself.
Anyone interested I would be willing to pick up extra supplies for you if you are along my route down south. Free shipping in exchange for beers and/or sailing? I will be driving from Alaska to San Francisco in late March or early April.
I also may be willing to build an extra rudder if someone was interested. Its always more efficient to do multiples for this kind of thing to defray the cost of setup, tooling, etc.

Good price for 655 Bronze rod.

Took a quick look at onlinemetals.com ($160) and Mcmaster Carr ($188). Then you have shipping...

By the way, Welcome Aboard

Couple of questions on the drift pins that go through the wood

Would you use threaded rod?

Instead of that, can you use solid bronze and cut threads in the end for the screws? What kind of tool does that?

How would the pins be secured to the rudder shaft. Just hammer the end that comes out the hole in the shaft? Weld it?

Howdy,
338's silicon bronze shoe was cast over in Richmond at California Castings.
From too many posts here you may have discovered that mine is oversize in that it follows the specs in the Manual. I don't know if the manganese b. rudder shoe available here on the site follows those specs. I understand the m.b. shoe has all the holes drilled and it's polished and ready to mount, and you can get your name on it, too, wow.

You can borrow my mold, which has the original motheaten one off 338 inside. (I straightened the sides which had been pulled in by bolts and filled in the corrosion with bondo, side holes too - and made the sides of the shoe a full 1/4") Unless you are particularly handy or have access to a machine shop, drilling the 3/4" hole for the shaft is a bit of a problem. Some would have to make an elaborate jig, while someone like Mike Goodwin for sure would probably do it behind his back. :D

Hey C'pete,
Use solid rod, fills the hole better. Threaded rod leaves spaces that would be hard to fill. Solid rod fills the bore hole exactly.
Easy to turn threads in copper
and why not tap the holes in the shaft for threaded rod/bolt also?

The hole would not have to go all the way thru.
The hole is essentially smaller not being a full size bore.
Threading the plank rods into a BLIND threaded hole has to be the cleanest, friendliest attachment method to the shaft. If you can keep the rod/bolt from going thru you will have less exposure to corrosion at that critical point - the wood of the rudder comes right up to the shaft in a 1/2-round dado and will beautifully cover that rod/bolt connection with bedding compound or rubber. No exposure there at that critical juncture if your alloys don't match exactly.:)

Ebb, Wow! That may be just the thing! My brother in Brownsville is a bit of an amatuer machinist and should be able to help me out there, I think he can do the work on the shaft as well. My specialty is the woodworking side. How much did they charge you to cast your shoe? Maybe I should have a few done for others who might want them in the future...
I'm thinking I will keep the bend design for 2 reasons 1.reduced stress where the bolts enter the shaft 2. Easier to get the rudder in/out without digging a trench. But I want to do away with the cutout and instead bore an angled hole for the bend. This should add some strength to the attachment. Any thoughts from those who have done a rudder rebuild?
On a slightly different note, when I was down last weekend I talked to Gene Roberts and he said there were improved tiller bearings & seals available, anyone know who to contact about these?

CP,
I was thinking about that topic, I will use solid rod of the same silicon bronze and either cut threads to screw rod into shaft or weld onto shaft directly. As added security I may pean the end of the rod onto the shaft. The threads are just cut with tap & die. I will ask my brother, the machinist about all this, he'll know better than I...

Tim, do "searches" on rudder shoe, rudder, rudder shaft, etc. and you will soon be up to speed on these subjects. A good bit of reading involved, but it will be worth the effort.

Bill's right. There's beaucoo stuff to wade thru, should do it, it's worth it. Stick to the traditional rudder building/repair threads. Explore this site here and you'll find Admiral Bill offers the shaft sleeve bearing at cost. This is the bearing that sits on top of the fiberglass rudder tube underneath the chrome cap.

The bend in the shaft, the two piece rudder shaft with the top part of the shaft bent, is the proper restoration rudder to make new. The upper shaft is bent to provide support for the upper part of the blade. This allows the blade to be cut away below to swing the prop for those boats with inboard engines. Evidently all rudders were built the same way, with the crooked shaft, but the blade was assembled without the cutout for OB models.

(338, an OB model with a well, had a hollow area glassed in where the corresponding gap in the keel for the prop would have been had it been an inboard.)

Many OB models have an "after market" single piece straight-thru shaft for their new blade, when a rebuild was needed. IMCO this is the easier design to make. All rudders are one piece and all one piece rudders will require that a hole be dug for removal - or the vessel to be lifted. The seemingly insignificant strap gudgeon is a very important part of the rudder system and has to be designed into any rebuild of any description.

Quote:

---

Originally Posted by Tim61N

Anyone interested I would be willing to pick up extra supplies for you if you are along my route down south. Free shipping in exchange for beers

---

Tim, That's too generous! I looked on a map and, technically, we're south of your starting point. So... :D

This assoc. forum is a great tool for jobs like a rudder rebuild. It's like a mini-web with only the information you're looking for. There has been lots of different techniques and ideas discussed here and you should find answeres to any of your questions. Who knows, you might add a new twist to the picture yourself!

Like C'Pete noted, that's a good price for the Si Bronze bar. One other note, being it is a 1" bar you may want to go with 5/4 mahogany, it's a full inch thick. I know, I know, I go around and around with my finish carpenter friend all of the time about how they're all involved in a national conspiracy to rip-off the public a quarter inch at a time.

Thanks for bringing up the bearing and seals again, I knew I needed to order something. Tony G

Northern MN?? It think that would take a few extra beers! Brrr, you're weather is probably colder than mine!
I wasn't thinking quite straight on the Mahogany, I will need 6/4 or a little thicker and then I will taper it down toward the tail.
I've already spent several hours on this site reseaching the rudder issue, but it's a deep vein, every time I think I found all the info, I just dig a litter deeper and find some more treasure. The amount of info here is amazing!

Tony,
Right on!
You could even go to 1 1/2 (even easier to drill the long holes for the tie rods,) and beltsand the blade down to its final shape.
Never found anyone interested in explaining just what the shape of our 40year old blade is in terms of chords. All the blades are dead flat - the ones I've seen on Ariels and Tritons.

IMCO a better shape would be to start with the thickness of the keel where the shaft is, take the fullness back a bit and then work in a mild chord to the end of the blade. That would leave more meat over the bolts, too. The original 1" thick blade had to stay fat because of the internal fastening system. The ends I've seen are blunt and rounded.

Modern blades get very thin at the trailing edge. They seem to terminate in a hard edge 1/4" wide. The 1/4" wide flat is canted ie NOT square or symetrical to the sides - to avoid vortexing the water leaving the rudder. One could mimic this 'modern' advancement by fabricating a rudder from hydroply and welding 1/4" plate to the shaft instead of rod. You would fasten thru the plate. Or have larger holes in the plate thru which you would glass to the opposite side. Realy strong way of doing it, to me. Ideas?

Just fooling around. :D

Quote:

---

Originally Posted by ebb

Modern blades get very thin at the trailing edge. They seem to terminate in a hard edge 1/4" wide. The 1/4" wide flat is canted ie NOT square or symetrical to the sides - to avoid vortexing the water leaving the rudder. One could mimic this 'modern' advancement by fabricating a rudder from hydroply and welding 1/4" plate to the shaft instead of rod. You would fasten thru the plate. Or have larger holes in the plate thru which you would glass to the opposite side. Realy strong way of doing it, to me. Ideas?

---

Seems like that 1/4 plate would add a bit of weight back there? How about just a "cap" made of bronze or aluminum on the end of the rudder with a nice feather to reduce vortexing?
Tim

A few items:

For CommanderPete's question, a "die" cuts threads on the outside of a rod. A "Tap" cuts threads on the inside of a hole.

For a nice feathered edge, copper strip might work best: easy to bend into place, and has natural anti-fouling properties.

I just got done doing the major part of my rudder rebuild: tapered two sheets of plywood, cut them to the right outline of the rudder, used various sizes of cove bits to put half of each of the bolt holes in the wood, epoxied the bolts, wood and everything into one unit, and next up is putting a layer of fiberglass over the whole job.

I didn't use a belt sander to taper it, but instead used a table saw with a carriage and a 3/4" wide dado bit. If anybody is interested in how that works, let me know.

I had a new shaft made, like Ebb mentions, the single shaft method. I had a machine shop drill and countersink holes for the 6" long 3/8"diameter flathead machine screws which cost me a fortune.

Had I to do it all over again, I would not have used the bolts, and probably would have gone with the drill and tap method like Ebb mentions. Although if the hole and threads weren't all the way through the main rudder shaft, the machine shop might have problems running threads all the way to the bottom of the hole. or might just charge extra.

And for Future Reference of All: Schubert's Welding and Machine shop in Annapolis is a one-man-show, who almost exclusively works in custom everything, and any material he can get ahold of. His number can be found on yahoo phone books. He made my rudder shaft and did it perfectly. and for an honest price ($300 for material and machining)

Quote:

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Originally Posted by mrgnstrn

I didn't use a belt sander to taper it, but instead used a table saw with a carriage and a 3/4" wide dado bit. If anybody is interested in how that works, let me know.

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Yeah, I'm always looking for new shop tricks
Tony G

Hey guys,
NO feathering. That creates the deadly vortex. Have to come to a sharp blunt end. Confusing.

But certainly I'm confused. The shop here has a French Inca table saw but we can't swing a 3/4" bit on it. So it's a dado set in there and I'ld like to know how you tapered that rudderblade of yors on the saw, yessir.. Now I can see propping the blade in a jig and sending it thru a belt sander a whole lot of times to get that taper. Very flat blade, for sure, would be the result.

How did you make the blade? With three 'planks' of plywood, as if they were mahogany? Thru drilled and all? That'ld be cool, you'ld have very little swelling or shrinking of the rudderblade.

Rod or allthread would have been a lot cheaper and easier to custom because you got both ends to work. And it's very easy to thread. You would have to go to a machine shop to tap holes. It's the lining up of things that a m. shop does so well, and that what we pay for.

Very high end carpenters known as 'mechanics' would do it all in the boat shed. And it is my visual experience that it is all in the jigs you make for the job.

As for flat plates versus rod/bolts. If the blade was tied together with frp, the plates welded off the shaft would not have to be very long. If the rudder was made of two fullsize pieces I can see the flat welded on pieces being short and a bit longer in the middle. They could have lightening holes drilled in them too. You know, whatever.

I have wondered if it's 'legal' to wrap the shaft with glass too? Go all the way round from one side t'other. Thats my plan. 655 takes epoxy well and it don't mind being covered, it ain't gonna corrode. The original rudder looks very elegant to me compared to all this plywood, glass and goop.

Make sure Alaska is selling you 655 silicon bronze. This is the legentary Everdur. It can be WELDED MIG.

Ebb,
From what I have gathered in my reading of rudder hydrodynamics, the reason for the doing away with feathering and keeping a flat blade would be to prevent the blade from stalling when turning. A feathered blade shape when turned at an angle would induce the fluid to create a vortex on the low pressure side of the blade, thus causing the blade to stall and the boat won't turn. If the boat were always moving in a straight line the ideal blade shape would taper off in an infinitely small edge to have the least amount of drag. I'm sure this is a very oversimplified understanding as there are a lot of variables involved, but makes sense to me.
Here is the spec sheet of the Silicon Bronze I got a quote for at Alaskan Metals it is a PDF, hope that comes across. I also included the spec sheet for Aluminum-Nickel Bronze which seems like another possible choice due to its strength and lack of zinc, but I have not seen much discussed here.

Tim,
Take your word on modern rudder design. The flat I'm refering to is the extreme back trailing edge (does not come to a knife edge), which should be flat and both its edges sharp. That is: this flat edge is more or less 90 degrees to the 'flat' of the rudder sides. It is only about 1/4" wide. You could only get this edge using modern composite materials.

The blade itself, the 'flat' part should have a chord to it, exactly the same each side. But what that chord is when upgrading traditionally flat, actually flat sided original factory Pearson rudders is open for discussion. Maybe it's not open to discussion.


Watch it with Alaska.
I personally advise Everdur 655 silicon bronze ONLY.
655 is the number. The correct number says it all.
Silicon bronze is a commonly available REAL bronze. Most available off-the-shelf screws, bolts, rod, bar, allthread, nuts, washers - if they say silicon bronze - are probably made from alloys close to 655. Not to aluminum nickle bronze, mango bronze, or petunia bronze.
There's nothing wrong with Monel if you're rich. Monel has no aluminum in it, last time I looked.

Not recomending anything, just saying what I did and why.
When ordering rod and bar you have to order by number - and sometimes by hardness.

Everdur 655 is the rolls royce of silicon bronzes, it is a specific controlled formula. We're really lucky to have it and regular silicon bronze availabe to us serfs. All the best wood boats of the past are fastened with it. To me it represents aromatic pipe tobacco, cuban cigars, scotch, leather, oakum, served rigging, highend varnished carpentry, and money. So it's prejudice on my part. And I don't smoke. I still think it is the best material, after much discussion here, for the rudder system on the A/C. Each to his own!!! :eek:

ok...a pictoral with commentary:

First, my representation of plywood as seen from the end-grain side.

next, put the widest set of dado blades into your tablesaw.
the one at the woodshop i go to is just shy of 3/4"
you also need a "carriage" for it. This is like a wide, shallow, open top box that has the correct hardware to slide in the grooves of the tablesaw.

This will allow you to prop up one edge of the plywood. you want to prop up the end that will be the thick part of the taper.
The black line in my drawing is the like the top of the carriage, or alternatively, the top of the tablesaw.
The red line is the cut line.
I should have put an arrow to tell the story better, but the plywood, the block propping up the edge, all move relative to the blade.

Now, this basically puts a groove only as wide as the dado, so shift the plywood ~1/2 inch into or out of the page, and run it though again. Repeat many times. Many many many times. Figure for a 48" long board, 1/2" at a time, with a few thrown in for giggles, ~100 passes. But really, once my jig was set up, ~10 minutes for the whole 24"x48" piece of plywood.

Now make two of these (you need will want to sandwich them together).

now you have one of these:

so, take this piece of plywood and cut out the profile of the rudder:

The shaded portion is the part you keep.

So, now put some bolt holes in....well half of each hole:
Use an appropriate sized cove bit (shown), and put a cove into each of the two halves. how you line up the two cuts is up to you. i made a few jigs to handle it. and lots of marks on each half to line everything up.

then you put the two halves together, and voile, perfectly lined up bolt-holes, down the centerline of the rudder.

ok, so there you have my method.

a few more points on the table saw method:


propping up one end works well, until you have make a number of cuts, like ~1/3 of the length. you can tell that the right side of my diagram has support before the cut, and the height of the thing you prop it with says the same after you make the cut, because the right side really doesn't get cut.

but the left side of my diagram needs to be propped after it is cut, because it isn't setting on the table saw anymore. So this is easy, just make sure to support the thin part of the board after you have cut it.

If more diagrams are necessary, just let me know.....

All -

Thanks for this thread, am learning much. :)

Thanks Capt mrgnstrm,
Tahell with theory - this is the real stuff! Thanks from all of us. Methods and methodology forever!

And with plywood one would not use a beltsander to shape a completed plywood rudder (as I wrote earlier :o ) because you want to keep the veneers intact. With mrngster's method the carved sides are the ones that are glued together face to face keeping the full veneers on the outside, making for a stronger unit.

Now I would like to see recorded here for prosterity a series of photos showing this alternative rudder being assembled. A series like this does not exist anywhere on the web or in a book that I know about.

And as folks who have not done it befor will say, there is nothing obvious about the steps or the process.

The tapering of the panels can also be done simularly with a router (from the top) - messier than the table saw method.

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The conundrum:

I believe a blade built in modern times should have some foil shape, more wing shape, some live curve to the surfaces, any opinions? Any naval architects in the crowd? Tried to explain earlier: when you start at the shaft fatter than the shaft with the wood - and bring that same dimension you started with further aft and then gently curve the sides to the tip of the blade - you'ld have a stronger rudder with longer bolts if desired. More wood.

And if curved correctly the rudder would then be able to generate lift. Rather than providing resistance when changing course and kind of slewing the boat around. IE, the curved blade uses both sides continuously to do its work - and the slab sided blade gets the boat to change course by sticking the wood out to halt that side , while the free side gets to continue on round.

Putting it bluntly:
Really wondering if adding a recognized modern chord shape to our rudder surface would get the A/Cs to sail any better, faster, or more responsive. Or should the blade be left dead slab flat as it came from Pearson? Or should it be the mrgnster taper??? :p

kp,
Great technique! Far less dust that using a belt sander and very accurate.

Quote:

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Originally Posted by mrgnstrn

but the left side of my diagram needs to be propped after it is cut, because it isn't setting on the table saw anymore. So this is easy, just make sure to support the thin part of the board after you have cut it.

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I suppose some long strips as thick as the height of the dado blade double stickied to the table would be a good prop.
What will you use to glue to two sides together, epoxy or something like resorcinol?
Tim

Just thought i'd get in here~~
Several subjects to cover, first off i gotta brag about going sailing this weekend!! Starting the season early, as it's looking like there won't be enuf water this summer to make spit, let alone float my boat. Pretty dry winter here in Oregon. So had a chance to go, weather was nice, had a bit of wind, so off we went. Awesome!

So on this rudder shaping/chord/lift making idea...which i think we covered somewhere before we had more experts come aboard....

I've heard it said the keel generates lift, by it's shape (chord?) like an airplane wing, or a sail. And possibly the rudder can be made to be a continuation of that shape, but i don't see how. My keel goes pretty straight back there. Of course it's been rebuilt, but i just continued the lines on back. Sure it tapers down at the rear, but not much. I don't see how making it with a chord will improve anything. A clean bottom, flush fittings, and no outboard hanging in the water to create drag and added weight in the stern will do so much more to improve performance than a wing shaped rudder. I can maintain steerage with my boat down to a snail crawl, and she coasts along forever. Anyway, just doing a little rambling here on what i think is more important. And i'm still struggling with the keel shape generating lift. I don't see how, with both sides being shaped the same!! On a wing or sail, you have the chord side, and the other flatter side, creating difference in pressure/air speed? I just can't see that on our keel. Yeah, it's nicely shaped to slice through the water, but lift? Come on someone, please explain!

On carving a new rudder, which i'll be doing when my rubber coverd mahogany finally gives out--or maybe the shaft will first--think i'll just use my stihl chainsaw. lol
Actually, here's a little work i did for a bit of nautical theme in the kitchen over the winter. Well, i did cheat and use a makita grinder w/sanding disc for the finish shape. Was going for an Airel when we started, ended up with something like a ketch!

Ya'll keep rebuilding, i'm going sailing! Thar is light at the end.... ;)

Tim:
Yes, thin strips stacked up as high as the dado blade is set would support the cut part of the plywood.
I found that 1/8" thick hardboard work wonderfully. Hard board is the same stuff as brown pegboard, but without the pegholes. And 1/8" is pretty good for most adjustments. after that 1/16" thick aluminum flat bar works well for any finer adjustment than that.

I used West epoxy to glue the two faces that I had cut together (cut face to cut face) so as to leave the unblemished faces outward. (of course, I went ahead and blemished the faces by putting 8 bronze screws on one of the faces to pull the two faces together enough for me to tighten down the machine screws/bolts and nut. oh well....)

Ebb:
Well, funny story about pictures of the process....there aren't any.
it was last saturday when my wife took my 1-year old son to a friend's house for a few hours (read: no parental responsibilities for a while, uniterupted). so there I am, outside on the back porch, preparing to mix epoxy, getting the vaccum bag ready, etc. and I thought to my self, "I should really take pictures". Then I saw the storm clouds moving. Well, I made a cursory round through the house looking for the camera, to no avail. But, it was now or never, so mixing epoxy and spreading and glueing took place before pictures. Luckily I got the epoxy down, the faces together, shaft on and tightened up, the vacuum bag over the whole thing and vacuum pump on before it started sprinkling.

by the way, vacuum bagging is hard. especially in the (relative) cold, raining, and really your first time doing it, and on a large piece. But, eventually i got everything sealed, but it took some liberal application of silicone caulking around the edge of the bag. in the rain.

lastly, on the profile of the rudder, if you look at the rudder as a flap on the end of a section, really it is mostly just tapered, and mostly straight sides. Like look at a NACA section, and imagine the front of the keel is the front of the section, the really extreme aft end has an almost inperceptible curvature to it.
If the rudder wasn't hung on the end of the keel, like for instance, a spade rudder, or a shorter immovable portion, like a skeg hung rudder, there would be a more perceptible curvature.

I browsed through Skene's Elements of Yacht design, and their example boat "Pipe Dream" is a cutaway forefoot keeled boat. The lines drawing in the book shows a taper, and again the inperceptible carvature of a faired in line.

as far as the extreme edge treament and eddies: I think that the overall aspect ratio of the rudder has much more to do with that.
I think that wheather the trailing edge comes to a fine edge or is squared off and 1/4" think has such an inperceptible difference that I don't think one would ever notice the difference. I plan on just using my orbital sander to round it over enough to allow for fiberglass cloth to lay on it and leave it at that.

I'm tossing in my chips that tapering the rudder won't make *that* much of a difference. Here's why:

A NACA foil of the proper shape for our boats will have it's maximum thickness at a point about 12% aft of the leading edge. The percentage is based on the chord length of the foil. NACA/NASA came up with a number of different shapes for different foils which serve different purposes. The actual overall shape of the foil is based on the speed at which the foil moves through liquid medium - air for a plane, water for boats. So we would want the NACA foil which was designed for 6 mph, more or less (I forget which specific foil # NACA gave this one).

If that is the shape of our keels foil overall, then the shape of the trailing edge - be it flat or tapered - will have little to do with how well the foil works. However, a tapered shape *is* more hydrodynamically slippery, and would work to take away drag caused by an over-wide trailing edge (and its resultant vortices).

Blah blah blah ;), at any rate, I think we are probably talking in hundredths of a knot/mph difference in the speed gain. I'd say at *absolute most*, a sweet taper would give a 1/10th of a knot, but I seriously doubt it would be that much. I'd bet that a properly steered boat with no taper would outrun a boat not steered very well which had the perfectest of tapers. :)

Our rudders don't need a foil shape, either, because they sit right behind the deadwood of the keel, and their rounded bar front edge probably works as well as any other shape to help bring water off of the keel and over the rudders surface. Our rudders are like flaps on an airplanes main wing trailing edge, where a rudder hung by itself (yuk) would be more like the airplanes tail surfaces, and thus needs its own foil.

Last thing - a symmetric keel/foil develops lift when the Angle of Attack makes the water striking it hit more on one side than the other. Angle of Attack is the difference between where the chord of the keel (straight line front to back, through the middle) is pointing, and the direction the keel is moving through the water. If your angle of attack becomes too large for your foil, instead of producing lift, it begins to stall and lose power (with resultant leeway), just like when you oversheet your sails.

PS - I don't mean to come off as a know-it-all. :) Because I *don't* know it all. :D Here's how I learned some of this: Smaller Com-Pacs (23' and down) come with a transom-hung rudder made from a flat sheet of aluminum - no taper, just some very slightly rounded corners, enough to keep the metal from cutting you. Some individuals had made foiled replacement rudders, and claimed they improved windward performance. Well, with a CP, anything you can do to improve windward performance is a Good Thing, so I set down and larned myself all about foils and all that, and started producing a design which CP owners could retrofit to their flat rudders. Luckily, just as I was finishing up the design process, Joel at IdaSailor stepped in and volunteered to help. Now CP sailors can buy a proper rudder from Joel. :) Some of my knowledge of aerodynamics also comes from being an aviation buff.

yeah, Epiphany's right......there are more-better things to do to improve hydrodynamics.....like keeping a clean bottom, or going with baltoplate or something, taking the outboard out of the water when sailing, buying a feathering prop, etc etc etc.

heck, about the only thing I do for hydrodynamics sake is untie my docklines when I want to go out, so as not to drag the dock in the water behind me.

well....that is WHEN I do go out....or IF i do go out (ok, so i am a little jealous of Willie.)

A tenth of a knot, eh? . . Well now, that's worth trying. Could equal many boat lengths at the finish of a race . . .

LOL - Bill, I knew you would say that. :)

I really don't think you'd see near that much of an increase. Probably it would be more like a couple 1/100ths. (Which might still be a boat or so... ;):D )

One design racing is soo competitive that if something will add to boat speed, no matter how slight, it's worth adopting. Hell, a 1/100 of knot would be worth it. :D

This photo posted on page 6 of Ebb's photo gallery. The design is taken from Alberg's lines drawing of the Ariel/Commander hull. It was likely added at one of the later drawing modification dates.

The rudder shape is similar to what is seen in mid 1960's and later heavy displacement designs. My guess is that it is more efficient and has less drag, but is not a pretty ;)

Hmmm... sounds like we need some more scientific way of proving this theory. Perhaps the association should sponsor a grant for me to make 2 (or more?) rudders. One perfectly flat, another with a certain taper. Observations will be made in various conditions i.e. wind speed, points of sailing, etc. Someone nuetral on the topic will verify the data and ensure the data taker(s) are reasonably sober. Thoughts???

Plywood too thin and the can too large.

Can see by quick History search we all had this words befor.
Yam gonna chord mah rudder, keeping it passably strate offen the keel awhile, not too much, and kinda fe e e el that mother in nice slow curves to the tip. No big letter chords, just pure technigue! This konsellation-style rudder lends itsel to shapely turns top to bottom.

There be no flat surfaces on ANY creature in the sea.

Y'all have in the A/C bottom the nicest curves there on any boat what has ever floated on water, it's almost criminal how animal that underwater shape IS. Personally can't abide that ear shaped appendage, jist naturally lean to that tip of a fin that wags there. Carl put that finny rudder on all subsequent designs of his, I believe. I know, I know, have to watch these emotions.

From the peanut gallery: during my time spent on the ComPac site, when I was thinking I would be happy with a trailer sailer like the CP16 perhaps, one of the mods for this boat which reportedly had fantastic results, was changing from the stock aluminum flat rudder to a fiberglass rudder with a foiled shape: less vibration and more responsive tiller were some of the improvements reported.

A BIG difference I suppose is that the CP16 is not full keeled and has a detached rudder...

Someone asked for an expert opinion on rudders. Ted Brewer, well known yacht designer, wrote an article on rudders for the Sept/Oct 2002 edition of Good Old Boat magazine.* Here is what he had to say about keel-hung rudders, amongst other things.

"Many older boats, such as the Folkboats, Albergs . . .and similar classics are full-keel designs with the rudder hung on the aft end of the keel. Keel-hung rudders are traditional and can be one of two types: outboard rudders, with the rudder mounted on the transom or on the stern of a double-ender, or inboard rudders, with the rudder stock emerging through a rudder port in the hull. The latter is more efficient when the boat is well heeled and the rudder is put hard over as it is less likely to ventilate (suck air down the low-pressure side) and so lose lift and steering ability.

The difference in the two types is not critical to the average cruising skipper though, and thousands of outboard-rudder yachts have made long and successful voyages . . .

The profile of older-style, keel-hung rudders was generally almost a half-circle on the trailing edge, or shaped like half a heart. Tank testing in the late 1950's and early 1960's showed that the better shape was to have the rudder squared off at the bottom, parallel to the waterline." [Karl’s added rudder in the lines drawing fits the picture.]

"As well, the top of the inboard rudder should be carried very close to the hull so the gap between the rudder and the hull is as small as possible. Less than a quarter-inch is desirable, and the thickness of a well-worn dime is better yet. Tests have shown that a gap of even a half-inch can reduce rudder efficiency by almost 10 percent due to ventilation. It will also increase resistance by several percent due to crossflow across the top of the rudder from the high- to the low-pressure side."

Ted then goes into a discussion of spade rudders that includes foil thickness based on NACA calculations. In explaining the popularity of spade rudders, he writes, "The spade gives the best combination of minimal drag combined with maximum lift and turning moment for its area."

[*Brewer, Ted, Rudders, skegs, and spades . . ., Good Old Boat 26, vol. 5, no. 5, September/October, 2002, pp 22-25]

Interesting.

I wonder how you would fill the gap between the top of the rudder and the hull (and still be able to lift the rudder out if needed).

Something like rubber weatherstripping perhaps.

I plan on using something sacrificial, like "good stuff" foam, shaped to the right size and clearance, then covered with a layer of F/G.
Or a strip of balsa wood.

crazy ole ebb, he will have the top of the rudder flat (spelt p h l a t, not rounded) and have there a piece of wood like teak that is screwed in from the top - by swinging the rudder to one side and using a short driver or the small rightangle 12v.

And the top of the fairing piece on top of the rudder is also flat, exactly matching the V-SHAPE on the boat that is over top of the rudder. If you want to get technical.

The two holes thru the filler piece are oversize but countersunk so no threads of the screws engage it, just the flat heads. Top of rudder is drilt proper for screws. IMCO this is a fairing piece not requiring an act of congress to hold it on. IMCCO you want it not sacrificial, but rubber might be good, if you plan on going aground. Talk this out.

I would use bedding compound, NOT POLY. This filler/fairing piece will keep the rudder from coming out of the shoe until the rudder is put way over. You have to be able to lift the rudder out of the shoe to pull maintenance. And to put it back in again. So you don't want anything permanent on the top. When messing around with the rudder it would be more convenient to take the fairing piece off until work is finished.

Embedding a pair of C'pete's barrelnuts in the top of the rudder with corresponding machine screws holding the fairing piece on would be too high end for an Ariel.


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See cleats like those on your rudder on Tritons that come into the yard. Seems to me if you are looking for super hydrodynamic flowsure patterning why in hell put the cleats on cattywonkus? Those bars should be horizontal, somewhat closer to the stream of water passing over the hull. If two aren't enuf, put on three, or four, but on a waterline. Picky picky, sorry :rolleyes:

Some might consider gluing on some hypolon flaps off the keel that would overlap the rudder, because that round rudder shaft there behind that squared off keel is creating vortexes that are slowing you down, too. :D

Well, what about when you have a little bit of rudder angle? BAM! gap up on top again. Put a big ol' 'bump' on the bottm of the hull around the rudder tube that is flat on the bottom so the top of the rudder and the hull never wander away from each other? Trim the sails so the rudder remains dead center? Never look at the knot meter, instead focus on forming tan lines? (imagine CPete'esque photo attched here) :cool:

Good point there Tony. We'll leave it to the engineers. You should go sailing with Willie.

I'm gonna keep riding my old rudder until it decides to fall off.

The original shape certainly does work. I've never had the boat do an uncontrolled round-up no matter how far she heeled over.

Quote:

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Originally Posted by commanderpete

I'm gonna keep riding my old rudder until it decides to fall off.

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Besides, if you did change the shape you would need a new PHRF certificate :p

That damn rudder is probably preventing me from bringing home the silver.

One time the Commitee Boat didn't even wait for me to finish. They just pulled anchor, went home and gave me a DNF.

The Indignity!

Commanderpete,
Here is a rudder design that might give you that winning edge.. :D

That would just be WRONG.

Proceed with construction (but paint 'em black).

Commanderpete,
Of course I was just joking, that would be HIGHLY unethical!

But hypothetically speaking you would of course want the 20hp submersible electicric motors with hidden batteries in the keel? :D

Commanderpete,
Here's another subtle mod that could be done for a little extra speed :D

I think that the rudder mounted motors probably would not be large enough to provide the thrust needed to dominate the SF Bay Fleet, as Bill clearly intends to do. Therefore, I propose this:

http://liquid-epiphany.com/images/ph.../ariel_jet.jpg

You'll note that it uses the engine from the Virgin Atlantic Global Flyer. I figure that that will be up for sale on eBay in another few days, and would be more economical to purchase than a new powerplant.

It may do better mounted on the centerline for cruising. This configuration is obviously intended to round marks to port only.

Waterski rudder

Here are some pics of my new rudder coming together. All the bronze parts were made from siicon bronze, rods were threaded directly into the shaft. I will use my leftover 3/8 rod for rivets for shoe and strap similar to original design. Rudder shape is close to original with a little more area down low like a constellation.

New rudder looks great Tim. Did you glue the pieces together? We are building a new rudder to match the original on Cup O Tea (Commander 290). There is no evidence of glue between the mahogany pieces on my original. Ebb has suggested somewhere that resorcinal glue is the way to go and I have it on backorder from Jamestown. My carpenter pal is tired of waiting for the backorder and wants to use a System 3 product (TAG?) But - the more I think about it - I remember someone here saying that the 1/16 spaces between the pieces in their rudder filled in when the wood swelled after being in the water. If the wood is bolted and screwed to the tiller shaft and has drift pins through it, and the pieces are glued together with 7000 lb psi glue - where is the give going to happen when the wood swells?

A friend who restores classic wooden Chris Crafts says they use 5200 exclusively between the boards. Stays flexible and gives a more natural ride. Does anyone think it makes sense to use the equivalent of 1/16 or 1/32 of 5200 between the slats to allow for swelling? And will 5200 hold up over time?

If "nothing" lasted 40 years . . .

Years ago I filled the gaps on my old replacement rudder. Might have used 5200, can't remember for sure.

I think it was a bad idea, the wood just swelled and made a larger gap.

I'd leave it open. Maybe a 3/16 gap with 3 boards. Possibly a larger gap with 2 big boards.

There might even be a chart somewhere that calculates how much wood swells

Nice work there Tim. How did you machine the ends of the rudder shaft?

That right. The traditional rudder need not be improved on in terms of method. Wouldn't you think the planks were just bedded in the old way of marrying metal and wood? If the boat is going to spend time out of the water regularly that's the way I'ld do it because you can maintain it.

If a blade put together with rubber dries out it may pull apart in a way that won't be easy to clean up. May wish you had put it together with a bedding compound you could just reef out and fill in again.

Polysulfide likes being underwater and is a longer lasting material than 5200. 5200 is so tenacious an adhesive that when a rudder dries out it is possible that the planks could crack or pull slivers of wood away at the seams. Polysulfide I believe is not as hard when cured and would be more likely to move with wood shrinkage.

So I agree with the method that leaves a seam for swelling. Seams payed with old fashioned bedding compound in a newly made plank rudder. When the boat is pulled next season for bottom paint, the squeeze out from the seams can be scraped off smooth, the rudder painted, and put back in. If the boat lives in the water, it'll remain tight.

This way you won't have to guess perfect how much to leave for the wood to swell. Fill it and scrape off the excess later. Mike may have something to say about priming the mating surfaces (the edges) with something. I might stabilize them with thinned epoxy

I guess the real problem is how to resist cinching up the long bolts too tight. One way to help keep the seams filled might be to plane the edges slightly concave. Tend to keep whatever you decide on in there. And thinned epoxy IMCO would be a great primer for the whole rudder. Befor assembly slather it on every piece all over and soak the holes. :cool:

There was a real big gap once I cleaned it up and dug out the sealant.

Couldn't tighten it. Ended up cutting the drift pins and pounding them out

Project continues...next year....maybe

Yes, I did glue the two pieces of my rudder together using system 3 epoxy. This was probably not necessary from a structural aspect, but I thought it would distribute any loads on the end of the rudder a little better. I will not use any glue on the bronze through bolts, so the wood should be free to expand outward. The expansion will not likely be significant since mahogany is so dense, so it will just tighten down on the nuts. I will will just tighten the nuts to snug to allow room for expansion. I think I will use some 5200 to seal the rudder shaft in its joint with the rudder. I am still contemplating glassing the whole works, not really concerned about keeping water out so much as getting a bit stiffer and a nicer trailing edge.
The holes in the shaft were bored and threaded with a vertical mill. The hardest part was keeping them all exactly in line all along the shaft as the mill table only had about 20" of travel and the holes are spread about 36" apart. We bottom tapped the holes about 5/8" into the shaft, and I think this will make a much stronger unit than the original. The straight shaft should distribute the stress all along the length instead of at the weakest point where the topmost bolt comes through. Looking at my old shaft its easy to see why it broke. There was very little stucture after the through hole and huge countersink. I also saw alot of evidence of leaching of the rudder shaft at that point where the through bolt was totally intact. This confirms my suspicion that the shaft was probably naval (brass) and the through bolts were likely sil bronze. So my rudder has all sil bronze, most of it all from the same source (the nuts on my through bolts were made with leftover pieces of the ruddershaft), so hopefully I will eliminate most of the galvanic issues.

Tim, Nice. Like the way you matched the grain. I think it was Theis who put a rudder together similarly. I worried about the rudder trying to relieve swelling stress by cupping - he said it didn't happen. Maybe the shape of a traditional rudder has something to do with that.

Congrats on getting the long holes drilled square! Hard, very hard. And end tapping the rods into the shaft is by far the very best method, elegant! That rudder looks great! :D

Thanks for the feedback and photos gents. We've been wondering about two pieces pieces in favor of the original three and it looks like we're in good company. I'm wondering if the three pieces had some distribution or flex function.

My carpenter pal likes to make things TIGHT so it will be a bit of a challenge to get him to just "tighten to snug". I notice on Tim and Pete's rudders that y'all have skipped the stainless peened straps on the outside. The original positioning is so weird (out of flow) but the original sure held together for a few years.

Scott

Have seen Triton rudders with the strengthening straps a right angles to the rudder boards. Could make them a little longer and turn them to the waterlines. Wonder why they put them on that way? There's one landbound T. rudder down at the yard whose rudder planks have shrunk - the metal cleats did nothing to hold them together. May have kept the rudder from bending, tho. Was that ever a problem? Maybe with a shrink and swell scenario the bolts loosen up inside and the added metal pieces were an attempted fix?

Shrink or swell the wood is going to do what it wants to. A plank rudder oughta be made from that nice dense honduras mahogany to survive the strange environment it's being asked to live in! Amazing, isn't it?

Gotta ask why Pearson didn't come up with a frp rudder for our frp boats?
Answer? No closed cell balsa available those days. :rolleyes:

My original rudder that I removed did not have the big straps I have seen on other rudders. The only straps it had were two small bronze straps to secure the inboard prop filler piece. Whats funny is that just after pulling the boat out of the water I poked at them a little and they just fell right off. Not doing a whole lot anymore I guess!! My original rudder was also made from 3 pieces. Most of the bolts were screwed into the wood except the very top one which had a nut. The outer piece was held on with screws or pins (not sure yet as I haven't removed them) from the trailing edge. I think the reason for 3 piece design is probably easier to manufacture and reduces material costs. I will take some pics today of my old rudder and post them.
Drilling those hole was a tricky operation. I took lots of time adjusting squareness on a very good drill press. I also use a very good quality brad point drill bit to start the holes about 6" into the wood. I then finished the bore with a longer bit and hand drill. It was also very important for the holes to exactly match the orientation where the enter the wood from the shaft. Any inaccuracy here and the stress would crack the wood. I used a template made from a piece of nice straight 2x2 cedar and cut the 1" dia cove just like I would cut on the mahogany after drilling. I put the cedar on the shaft and trasferred all the centers of the rods onto the template and then used this template to mark my drill points on the mahogany. I was very careful with measurements and used a very accurate scale and square to mark the template. Remember measure a dozen or so times and cut once!
I don't think I will see a cupping problem as those 3/8 bronze rods are quite strong. Having 5 rods should distribute the stresses well across the rudder hopefully. We'll see how it worked next haulout!

Quote:

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Originally Posted by Tim61N

My original rudder was also made from 3 pieces. Most of the bolts were screwed into the wood except the very top one which had a nut. The outer piece was held on with screws or pins (not sure yet as I haven't removed them) from the trailing edge.

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Yes, that's the Pearson original that has lasted only 40 years :eek: Manual has a complete description of it and r&r.

Well, we're going to pretty much duplicate the rudder we took off of Cup O Tea - straps, drift pins, bolts, wood screws (what a conglomeration!) and all - with the possible exception of going with 2 pieces. We're using quarter sawn Hounduras mahogany opposite grain facing. Still contemplating cauking between the slats - haven't decided on that yet. We'll see how she holds up! Thanks again for thoughts - will post pictures when we're done.

Scott

In leiu of starting yet another rudder thread I figured I'd hijack/borrow/resurect this thread.

Looking at other vessels, being of varied keel systems, why is our rudder so very small comparitively. I have seen quite a few boating in the yard most being transom hung, but all with notably more surface area then ours. Would the Ariel benefit from additional rudder surface area, maybe even bringing the rudder up the rear a little also (above the attachment point).