km mrgnstrn's rudder method
Starting on pg11 of this thread, this method uses plywood to build the rudder.
It would be most useful for a rudder with an aperture, and relatively simple and elegant way for a single piece straight shaft
It uses the same 1" silicon bronze rod for the shaft and smaller available bronze rod drilled through - or tapped into the shaft could be done without welding.`
I believe the plywood could be sheathed or wrapped in glass or just sealed and epoxied if you want the traditional/restored look of plank married to the shaft.
Without thinking twice, I would use Hydrotek meranti plywood from a well established dealer. British Standard: BS 1088. No american plywood merits this high grade. It is perfect plywood if you are following mrgnstrn's method because it is clean, tight, voidless, modestly priced material for woodworking tools It would make a really fine plywood rudder imco.
This rudder when sealed well will probably take extended drying out periods if the boat is pulled for the winter or for traveling.
If put together with good epoxy it would last another 40 years. Damage would be fairly easy to repair - and if it had to be wrapped with fiberglass later to keep it going, that could be accomplished simply. BS-1088 meranti is engineered from red lauan. Imco it will do better than any other plywood underwater BUT edges must be totally sealed.
It will make the tapering and a thin trailing edge that much easier. I have bought meranti dead flat, every sheet of amerkin ply has a built-in curve. Flat material will be so much easier to taper with mrgnstrn's method. Might even factor in a modern foil shape by spreading microlight filler on the flats and shaping with a belt sander - adding a light fabric skin to protect the surface.
thicker rudder and a construction idea
Never seen those offsets myself. Only the general dimensions.
You can find controversy as those drawings in the Manual also imply that a wider rudder WAS once planned for the Ariel and maybe the Triton.
But of course the shoe only allows a 1" shaft. And therefor a thin rudder.
Pics of the traditional plank rudder show them to be no more than an 1 1/8" thick. The rudder would have to be almost totally flat and of consistent thickness to be built with the internal fastenings as we know them.
The finished rudder is skinny and relatively light.
There is no reason imco that a heavier rudder couldn't be built.
The only problem is holding back the bulk at the shaft so that the rudder can be swung. The traditional rudder has no problem going the full sweep of the tiller in the cockpit.
Don't know that the extent of that sweep has been translated to how much there is to the rudder on the keel. Any thickness at the shaft obviously will limit its swing because the rudder is inset into a cove on the 'keel post'
Can relieve the rudder wood at the shaft back so that the swing is maintained.
But that will change the flow of the water off the underbody onto the rudder and might create eddies or turbulence over the blade. Don't know.
A thicker rudder will ease the fitting of the planks together.
Imco a rudder made of thicker wood begs that the rudder sides be shaped into a bit of a modern foil.
Imco a keel hang rudder uses only the trailing HALF of the modern wing foil. An easier shape to introduce onto the rudder.
The curving of the trailing half of a foil is rather mild.
However a trailing foil wants to be thin. And that is a real problem with a round rudder.
And maybe the reason round rudders are left flat.
I think a more efficient rudder can be shaped, one that is less likely to cavitate. Don't know if this has been observed as a problem with A/Cs.
With curved sides the thickness can be carried further aft which may allow the third plank out to be fastened differently.
(Slightly different construction method.)
IE, if the third plank does NOT have the long rods that go thru the second and first to the shaft, why can't the third plank be permanently glued* to the second? Could be slipped over a couple blind bronze pins for reinforcement. And if things work out could allow carving down the trailing edge SOME.
When building the plank rudder the nuts on the ends of the the long rod/bolts/allthread need not be buried in counterbore holes. The nut and washer and bolt ends can be notched into the second plank. They would be totally exposed in open square cutouts - tightening, loosening and adjusting at will. When the rudder is finished, the square holes can be filled and faired with non-hardening putty. When painted the holes will have disappeared.
Later when maintenance is needed and the paint is removed, the major fastenings will be right there! The nuts could be backed off and the blade taken off the shaft without an act of congress.
This is imco - I haven't done this, but it appears feasible. Putting this out for discussion.
The traditional rounded rudder however goes back to a time before rudders were hydrodynamic. It might be too difficult to give a foil shape to a round rudder.
Anyway, with thicker planks some more dynamic but mild curves might be added to a new but traditional blade.
Might entice the Ariel/Commander to go a little faster and enjoy a little more control.
???
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* The traditional rudder is NOT glued anywhere - giving individual planks some room to move. The usual 3 planks are generally of equal width, about 6".
The original rudder was assembled DRY, altho they may have used a thin coat of bedding compound on the edges and certainly at the shaft to plank join.
However, in this case, the suggestion is to glue on the 'third plank' - the outer and smaller PROBLEM plank. It interferes with no clamping threaded fasteners, not even screws. It is free to swell and shrink.
The middle plank could be an extra wide plank incorporating the third plank. A two planker,
But clamping nuts and washers introduced into the outer edge of a less wide second plank is easier, The same ease of assembly and disassembly of the rubber blade could be achieved in a very wide plank by mortising out the access holes at about the same distance out if a three planker.
So much easier to bore long centered holes in less wide material.
Resorcinol is the perfect underwater bonding glue for mahogany. Maybe a rubber adhesive could be used....
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Miro sorry it took a bit for me to get back to you....
As you can see our hard working forum administrator has merged this thread with the main one on the topic. And because of it there is probably a lot more information here now than you will be able to read in even a couple of sittings.
But to answer the specific questions you asked me, and since I don't know how much you already know or not I will go into detail. I'm sorry if I am wasting your time telling you things you already know.
I decided to use quartersawn mahogany because it is much more stable than flat sawn mahogany. Most people know that wood shrinks and expands as it takes on and gives off moisture. What many people do not know is that the amount of movement varies based on the orientation to the growth rings. For example, for all practical purposes wood will not shrink or expand in its length. While not 100% true the amount of change is so small it usually is not worth considering.
Take a look at the drawing below. If you were looking at the end of a log that was being cut into lumber you can see the boards I have labeled as flat sawn have a different orientation to the growth rings than the boards I have labeled as quartersawn. The growth rings are for the most part perpendicular to the face of the board in the quartersawn boards and they run more parallel to the face of the board in the flat sawn. Flat sawn boards will shrink and expand almost twice what a quartersawn board will. In addition because of the orientation of the growth rings they will tend to cup and warp much more than quartersawn boards.
To illustrate my point you could expect an 8" wide flat sawn board to expand by .05" when it goes from 8% moisture content (a good level for furniture building) to 28% (saturation point) while a quartersawn board would only expand by .03".
As far as where to buy the material that depends on where you live. Some parts of the country have much better access to lumber than others. I would look first in the yellow pages for hardwood lumber retailers. Then call cabinet shops in the area if you cannot locate anyone you can buy from direct. They will often sell you what you need with a small markup for their trouble. And if all else fails do like I did and search on the web.
Another Rudder Shaft Replaced
Greetings:
My name is Dennis, and I've owned "Sinbin" since 1994. After 48 years, her rudder shaft came apart in my hands as I was dropping it down for inspection. I was happy it broke because I was on terra firma. Thanks to this discussion, I have, through the years, collected a stock tiller cap, a stock rudder bearing, and now a new rudder shoe thanks to a fine gentleman by the name of Chance.
Svendsen's Boat Works in Alameda replaced the upper and lower shafts, the six attachment screws and the gudgeon, all in bronze. Excellent work and reasonable rates. I now realize I've had sloppy steering for 18 years.
Anyway, I'd like to thank you folks for the info, and I'd like to recommend Svendsen's for your repairs.
Old Knotmeter showing nearly 10k
One more thing, the reason I posted the knotmeter instrument is to say that I have removed it. I could not find a replacement prop. I am considering making a taffrail type unit using the knotmeter head and making a box to contain it, dragging a prop behind the boat, because the head still works beautifully. I have installed a modern knotmeter in the bulkhead but it uses power and probably won't last 50 years like this old one, lol
rudder current condition?
rudder forensics: The Case of the Crystalline Heel from Hell
Captcraig,
Look at Miro's post on this thread #341'
Your rudder photo SEEMS to show that same original Pearson rudder.
Imco you might do as Miro and take the bloody paint off.
You want to see what's going on !
When A338's rudder and everything else (except the rudder tube) was taken apart,
Discovered that the heel fitting (rudder shoe) was barely held on by its fastenings.
When I took it off I found that half of the bottom of the keel there was broken pieces of crystalline plastic.
The hull when it was made at the factory was layed up in a single mold.
That meant that the narrow hollow of the mold at the stern had to be perfectly done.
On A338 it wasn't. The workers had not punched the fiberglass reinforcement all the way into the farthest corner where the rather short
heel fitting is mechanically connected. Even after 337 Ariels, before A338, they broke for lunch too early.
That meant when the fitting was attached with its original four pins, some went through unreinforced polyester....maybe one or two pins were doing all the work.
I see in your photo at the very bottom that part of the boat is missing.
It does look like your heel fitting is tight. BUT........
There is tremendous weight on that part of your rudder system. Guess 30 to 40 pounds deadweight.
THE WHOLE NON-BOUYANT RUDDER SYSTEM, INCLUDING THE TILLER HEAD, IS BEARING ON THE END OF THE RUDDER SHOE
There must be tremendous forces on that fitting when the rudder is really working. Assume that offshore forces will be multiplied.
I would get that rudder off and take a good look at the end of your keel by removing the heel fitting and suss if Pearson got glass down in the end there. Amount of fiberglass tenon inside the fitting is 2 to 2 1/2" wide and not much deeper. A bit crazy... whole steering system...???
Basically the rudder shoe needs to be connected with the remainder of the vessel.*
Pearson getting it perfect by hiring Azorian farmers to jam glass and smoking polyester down into the mold with broom sticks (may actually be true) was a matter of luck. Don't know about skill. After 338 Ariels, breathing all that polyester, you got skill. Ayedunknoe?
Take a good look at what you got there, before you go briney.
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Also scanned the long c'amos quote post #355. "Sintered Bronze" is not a description of bronze rod. Sintered bronze is a high pressure powdered bronze reconstituted usually into SAE or silicone oil infused sleeve bearings.
Plain 655 cold rolled silicon bronze is the most reliable material on the planet for A/C rudder assemblies.
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*A KEEL/HEEL EXCAVATION
Of course there is no perfect. And there are 100 ways to fix anything. This is what we did, doesn't make it gospel.
When cleaned up, the heel the tenon, that the rudder shoe was supposed to be mortised on A338, was almost non-existant!
Drilled two deep holes, six inches straight up from the bottom, into the keel. Didn't go through to the inside.
Can't recall exactly what size lag bolt, 3/8" or 1/2", step-drilled the holes so that the bronze lagbolts had to be turned really tight into position. Glued them in with epoxy. Had hex heads, washers and a bit of the shank sticking out enough so that they could be wrapped in saturated biaxial mat...
While the guys who molded the hull didn't get the bitter end of the keel done correctly, they did stuff in a bunch of cuttings and matt
against the keel-post to created a back flow ramp so that bilge water would collect more forward in the sump. This made for a very solid block to drive the bronze implants into.
Used California Casting's freshly minted rudder shoe lined it with seran wrap as the mold, filled it with saturated X-matt and jacked the fitting into place. There was still enough keel tenon & shoulder left to get it to seat exactly. Had to plan for the shoe pins so we didn't run into anchor bolts when drilling thru the rudder shoe.
We, Littlegull and I, think we have solved our Case of the Crystalline Heel from Hell. Hopeso:D
Hope this helps some.
Osage Orange, Bois d Arc for a rudder
Farmers here in these parts planted Osage Orange in large numbers as hedges along the fields after the dust bowl to slow down the high winds we have. They realized that the branches made good fence post. Of course the indians made bows out of the hard stuff for centuries. Fence posts out of OO have been documented to last 80+ years. Would be fun to experiment with it for a rudder. Its not easy to work with though, hard as nails and the older it is the harder, so best to work with it green. Off topic but my great great grandfather was a landrunner in the Cherokee Strip Land Run and kept a day book (diary)
