Has anyone ever done that? I searched the site and couldn't find any examples or comments. Everyone usually makes a whole new rudder. I was thinking of fairing the original beat-up one I have.
Comments? Suggestions? Intervention? Save me from myself?
If you have the original bronze and mahogany plank rudder, it is as fair as it will ever be
because inside there are bolts attaching the planks to the shaft,
that because of the rudder's dimensions, cannot be trimmed down any further without
weakening the structure.
If you grind off the trailing edge, and with that some of the body, you will only weaken
the wood and probably expose the internal rod and nuts.
If you have an ear shaped rudder, airfoiling won't make a difference in the performance
of the boat. If you are considering a rebuild, Alberg designed CapeDorys with angular
rudders that can be airfoiled. And one of the drawings in our Manual shows an outline
of the more modern rudder in dotted lines behind the original rounded one.
I believe the original bronze and mahogany rudder to be a work of art.
Many have lasted 50 years in and out of the water with minimum maintenance.
Don't think a new plywood and plastic rudder could last that long, no matter how well
made. The original rudder can sometimes be taken apart, and the mahogany replaced
with what it was made with, real Honduras, and it'll give you another 50 years with
no problems. You may want to find a shipwright to do it. Have to drill long holes
thru 1" width wood, takes some skill.
It's possible that if you clean it up, take it down to wood again, it might still be
serviceable.
WHAT I WOULD DO IF THE BOAT WAS NEW TO ME
IF your Commander is out of the water, remove the bottom paint from the rudder.
Carefully inspect the length of the shaft for telltale evidence of metal corrosion.
Look at the heel fitting where the shaft is seated. By rights you really ought to remove the rudder from the boat and inspect the unseen part of the shaft that's
inside the rudder tube. You should, if you are new to all this, also remove the
tiller head and check out the bearing and O-rings and keyway and bolts there.
You will have to take that apart to be able to slip the rudder out of the boat.
You will also have to open up the 'gudgeon strap' (at the midpoint of the blade at
the shaft) to move the rudder 3/4s of an inch up - and then over - and then down
past the heel fitting when removing.
Some have reported the absence of this strap. Not much, but it is vital to the
safety of the rudder.
Your boat will have to be lifted to take the rudder out of the boat, or dig a hole
where you are to drop it far enough to clear the top of the shaft.
Saying this, because there is no palliative (like a coat of plastic) that will cure
the problems of an experienced and neglected rudder. Imagine suddenly loosing
your rudder, suddenly not being able to steer, out on the bay...
By fairing I mean coating the mahogany with epoxy and fiberglass. the only other thing I'd do is replace the mahogany boards as you suggest. lots more work.
Last edited by roythomas; 07-19-2016 at 10:42 AM.
Reason: additional info
Experience tells us that covering planks with frp is not a good method. Water will still
get in and the encapsulation will delaminate because solid wood expands & contracts.
Some wise guy will come along and tell you that if you really soak the old DRY wood
with multiple coats of laminating epoxy and then cover the result with 3 or four layers
of 8 or 10 oz woven glass -- stapled on with monel staples -- you may have a chance
for success. You might have to take a wrap or two around the shaft with the cloth,
and you have very little room to make that possible -- but somebody's probably done
it! You are attempting to immobilized a system that has swelled and shrank a 1000
times before.
You will be adding, depending on technique, considerable extra weight and thickness.
You have to add enough glass to cancel the swelling of the wood. This may not actually
work. That's why you have to staple the cloth to the wood, this also may not be enough.
Getting the epoxy to grab onto the old wood is a problem. You will have to depend on
the shell you are creating. You'll need good epoxy, good technique, and there's always
the possibility that the rudder blade will just not like what you are doing to it!
Epoxy isn't the wonder cure-all plastic its cracked up to be. Imco there a 50-50 chance
you'll have trouble with it living under water as part of a plank rudder, and that's having
good luck on your side.
A dried out rudder looks a lot worse than one that is fresh out of the water. All it needs
is a good soaking to swell planks and cracks closed again. A rudder can be renewed by
cleaning and a little sanding, if dry some one part primer coats and bottom paint.
Fair, no plastic.
Success with depend on the condition of the rudder parts you are encapsulating.
Covering rudder won't fix mechanical problems with old age. In the Manual,
in Section E, pg170, we have a drawing of the A/C rudder with dimensions. In the
short list of 'NOTES', it reveals that the original rudder stock (shaft) was "MADE OF
NAVAL BRONZE". Naval bronze is actually naval brass. It is a 40% zinc alloy.
This alloy self destructs in the right conditions, the zinc acting as anode to cathodic
copper, in saltwater electrolyte. Corrodes and becomes porous. Manual warns this
happens to the stock around the waterline inside the rudder tube, where it cannot
be seen unless you drop the rudder. Page 170 rudder drawing does not show the strap gudgeon in the middle of the
lower half of the stock. It cannot be left out of a fully realized rudder. Grounding
can lift the rudder out of its heel socket -- the gudgeon acts as a guide, insures that
the shaft will reseat itself.
Silicone bronze will probably last 4000 years in your boat. And since all available bronze
fasteners, allthread and rod happen to be 600 series silicon, there can be no galvanic
metal corrosion in an immersed rudder put together with this incredible durable stuff.
It's possible that a new rudder, that includes bronze, epoxy and fabric, is in your future.
There are as many ways to fabricate a new rudder as there are owners. Because of
experience, rudder dimensions, and materials, imco there are criteria we have to stay
within keeping the bronze shaft. Which so far, almost everybody seems to have done*.
Other materials like stainless steel are verboten for underwater use. I would also stay
away from manganese bronze which has 25% zinc in it. It's a handsome bronze for
on-deck yacht fittings.
IN CASE YOU WANT A NEW RUDDER One inch diameter 655 silicon bronze rod is readily available and not too expensive. 655
bronze sheet for welding gussets is harder to find. You can design your new rudder to
use smaller diameter rod (like the original bolts & screws) to hold the blade rigidly to the
shaft, but instead of solid wood planks use marine ply, and/or pvc foam, and frp. It's
possible to make a composite rudder with a full length shaft without a prop cutout -- and
maybe possible to include the prop cutout without having to bend the shaft you see in the
original, essentially by simply leaving a 16" length of 1" rod (3lbsft) out of the middle of
the 6' shaft. Depends on quality of materials and design. Haven't done this myself, and
will not leave the dogleg out on a no-fiberglass new 3-plank mahogany rudder.
You'll have the rudder stock prepared by a machineshop, who will reduce the diameter
of the bottom end to seat in the heel fitting, cut in a keyway up top for the tillerhead,
and precisely make blind threaded holes** along the shaft at various locations for the
smaller diameter rods that join the blade to the shaft.
** not to push your design, let's say ebb's suggestion here is that 3/8" 655 allthread is
a less expensive way to sub for the original bolts and screws noted on page 170 in the
ArielAssociation Manual. It's my opinion that blind 3/8-16 holes in the 1" bronze stock
positioned of course on the blade side are less likely to weaken the shaft, and are
protected by the composite construction of a Meranti ply and epoxy/glass rudder blade.
Built this way the rudder can not be taken apart... but imco easier to maintain!
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ~~~~
*There is a 22page thread here in the archive called rudder discussions.
It is the best thread you'll ever find that talks exclusively about our A/C rudder.
Answers all your questions -- you'll meet a whole bunch of folks in the same boat as you.
HOW TO GET THERE
Currently you'll find 'rudder discussions' near the top of the sticky list of threads on the
lead page of theTechnical section.... DIVE IN!
that rudder price is totally outrageous!
Wonder if your carpenters know what they are doing
or trying to reinvent the wheel.
Professionals would have no problem reproducing the
original at half that price or less. imco
If properly built, a new rudder is going to cost several thousand. I made one out of mahogany last year. The rudder shaft was in good shape, and could be reused, but I replaced all of the bronze hardware (lag screws and drift pins, etc.). Cost of materials was probably less than $500, but it took me about 40 hours start to finish - and I had access to a professional grade wood shop. Luckily, my original rudder was on hand to copy. But after 50 years it was time for replacement. The new rudder got a few coats of bottom paint - nothing else. Hopefully it lasts half as long as the original!
aoquinn,
Looks like you've maybe included a mild 'airfoil' taper to the mahogany...?
The parts list with the page 170 Manual drawings also don't look like what you have for the original.
Also missing in the Manual list are the 'drift pins' used to attach the third plank.
Can see 1/4 or 5/16 hexhead lags bolts here. What did you use??
Notice any difference with the extra square inches on the trailing edge?
Here's a photo showing the approximate configuration of the rudder hardware. Checking my notes, it's all 3/8" bronze, which was sourced from ccfasteners.com for $125. The mahogany cost $140. Access holes for the internal nuts were filled with autobody filler after the rudder was mounted to the hull. Then everything covered with bottom paint.
One of the more challenging tasks was aligning holes at different angles through all three boards. It would be easier with a drill press large enough to accommodate all three boards AND a drill bit long enough to get through them.
Can see how that takes some of the mystery out of how the traditional rudder is made!
Can really see for the first time how it was done. But a while ago I went with a straight
stock, meranti and glass composite, without the cutout. If I wanted to do the original
rudder, I would also use unthreaded rod, but looking at the drawing from the Manual
and your photo, I'm thinking why not have all the 3/8" fastenings at 90degrees to the
shaft?? Even the dogleg in the prop opening... stack and tie the whole thing together
wherever needed. For somebody building a new old-style rudder, with new 1" bronze
stock, following post, has a logical way to proceed, in my opinion...
nice looking rudder!
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