rudder discussions

[ebb]

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.

[Tim61N]

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!

[Bill]

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.

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

[CupOTea]

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

[tha3rdman]

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).

[mrgnstrn]

I think it has to do with the fact that the rudder it attached to the keel. No part of the rudder is forward of the rudder shaft.


When it isn't, like a fin-keel boat with spade rudder, I think that there isn't enough lateral surface area back aft to provide lateral stability, so they have to add area back there. They might add this area forward of the rudder shaft to balance the helm somewhat.

Just a guess.

I can say from experience that the Ariel tracks like its on rails, but my 35' C&C could probably turn a 180 *inside* the same turn by the Ariel. (it would be close)

[ebb]

Seen a fair number of keel-hung rudders (on chunky wooden cruisers) come thru the yard - and yer right, nearly all of them seem too small compared with the balanced and skeg rudder. Especially older boats with the ear-shaped rudder like on the A/Cs.

One reason may be that the force needed to turn a barn door rudder probably increases exponentially by fractions of inches, so they can't get much bigger than designed without getting impossible to turn. Wouldn't mind hearing a partial dissertation on this subject. Maybe a bigger rudder would be more efficient, it's that its size has to be compromised.

I'm surprised that the Ariel turns so sluggish, given its cutaway keel profile. That's a good thing for tracking as you say. it's like my Dodge truck compared with a Honda. A little more sprightly turning and a tighter radius would be better. 338 does intend to try out the constellation alternative of Alberg's on page 148 in the Manual.

imco, A rudder of either shape built modern with a slight arc to its sides and coming to a sharper trailing edge would make it more efficient - and one might expect it to liven up the steering, right?

__________________________________________________ _________________________________
Not going to convince the traditionalists on this forum who must imitate past methods when reviving their boats. If the Ariel represents the great historical leap forward from wood to plastic then why wasn't the rudder included? (well, you know me, I think Everett couldn't be bothered.) The traditional A/C rudder is obviously better matched to a wood boat. A composite rudder more suited to Ariel/Commander provenance HAS to be considered the correct upgrade. It can't be argued if it makes for a better handling boat! Underscored. My deflector shields are up.

[ebb]

Check this out:
"The main difference between a 'thin flat plate' and a NACA foil is that the foil will generate lift, ie power, at a higher angle versus the boat's direction. Where a plain flat rudder will stall and simply slow you down somewhere around +/- 5 to 10 degrees from center, a NACA foil will be effective over maybe twice that range. Your boat's rudder will work better. Tacking will be easier. A little bit of weather helm translates into more sideways 'push' upwind." Craig O'Donnell
google >Foil FAQ< www.boat-links.com/foilfaq.html


A rudder creates drag evertime you move it. I believe a foil shaped rudder would even help the keel create lift and not stall the asymetical heeled shape out, which seems to happen alot on one boat I know.

Hope to 'generate' not only lift but some discussion...

[c_amos]

On haul out, the rudder looked pretty good. It was covered in the same slime that had built up over the rest of the hull;



The straps you see were added by the prior owner, Herb Tucker and appear to be holding up well. I did not remove them, but sanded them down, and they seemed to be in good shape. There is a split in the rudder along the seam where 2 planks were joined (I can see at least 5 bronze rods (pins?) that run through from the end.

The split had been filled with some kind of Calk on the last haul out, which seemed like a good compromise to me.

Here is the rudder after pressure wash;



I sanded it, coated it with epoxy. I coated it with epoxy, faired it in and painted it.

Here is what it looks like now;


I felt like the rudder was in pretty good shape. The straps that Herb added seem like a reasonable precaution to prevent the end of the rudder (beyond the seam) from sliding off.

[CupOTea]

Hi Gents - Hopefully there are pictures of my new quarter sawn Honduran mahogony rudder attached to this post. For reasons previously discussed regarding wiggle room for wood expansion etc (and before reading Ebb's recommendation to make it out of one piece) - we opted to make the rudder out of two pieces. Everything else including the bronze pins and bolt boxes was made to match the original - except for the two stainless straps that were peened on there - maybe at some point by PO to hold the old one together.

Now I'm wondering. Should I just give the thing a couple of coats of penetrating epoxy and leave 'er be? Should I bother putting some glass over the seam of the two pieces?

[CupOTea]

After loading my rudder photos on Ebb's Photo Gallery thread - I found this thread.

If anyone has advice on finishing this rudder and would be so kind as to go over to that thread and weigh in, I'd appreciate it.

[Tim Mertinooke]

I removed my rudder and it was in great shape so I was in a similar position that you are. After asking around I decided to leave it alone and just paint it with bottom paint. I considered CPES but decided against it after some credible people told me to leave it alone.

http://triton381.com/forum/viewtopic...128aaf4b82de9c

[Theis]

I loaded up the wood with sealer(4 or 5 coats asI recall)put on bottom primrt and bottom paint. Swatchesof the bottom paint have come off at years end, but the mshogany is stilll solid after about 10 years in fresh water(Emersion in fresh water is hrder on mahogany than in salt water, or so I understand.The wood should not be encased in glass because the woodwill rot in my opinion- particlarly if the vessel is hauled where it freezes

[Tim Mertinooke]

Theis, what did you use as the initial sealer?

[ebb]

Hmm, If I messed it up, I meant to say that the OB model Ariel rudder can be made with a SINGLE piece of rod. Since there is no cutout for a prop it is appropriate and much stronger than the two piece bend rod rudder that I understand ALL Ariels had on them. OB Ariels had an insert/plug in the aperture. Or some didn't.

The mahogany part of the rudder, the blade, if it is a traditional stack of planks, should not be a single piece of wood. Although at least one on these pages is just that. (Theiss' ?) The reason is that woodworkers believe a single plank can absorb water and warp in relation to the log it was cut from. Two boards stacked edge to edge are less likely. And three planks even more unlikely to warp. You reverse the grain when stacking. If you have to have a wood rudder, noble mahogany is the best next to the king of woods, teak. Because neither is known for warping much.

Whether you glue the planks together - or use a rubber adhesive - or merely use a bedding compound is still pretty much open for discussion, isn't it? Whatever I did I would still seal all surfaces with thinned epoxy so that water absorbsion is equalized. And it's a good primer for subsequent paint. The rudder will swell some in the water (and shrink some when out of the water), so I would allow for that by not sweating the long thru-bolts/allthread fasteners - or you'll just be crushing wood fibers where you needn't. And when dried out the planks will be loose. Just snug on the nuts.

As I understand it, as long as you keep a wood rudder clean and painted nothing much is going to happen to it. So it doesn't need to be encapsulated.
If you have an old rudder, that's showing its age - then a quick fix and a new lease can be had with fiberglass and epoxy.