Fiberglass cloth or not?

Rudders are a difficult thing to make using solid lumber or plywood. This is a place where inert materials like GRP do shine well.

A few coats of epoxy will not help a solid stock or plywood rudder much. Though I usually agree with Alan, the $20 a month rolleyes: ) he sends me to arbitrarily boost his "reputation" points isn't affecting my opinion on this subject.

Rudders and their cheeks take a lot of abuse. The leading edge, trailing edge (oddly enough) and the faces of the mating surfaces within the cheeks, see much more abuse then a few coats of straight epoxy can handle, when on wood.

Let me guess, your rudder head is comprised of two outboard solid lumber cheek pieces, capturing a plywood spacer, which is just thicker then the rudder blade? The less dimensionally stable solid lumber cheeks moved more, in relationship to the more stable plywood spacer, pulling, twisting and testing fastener ability to hold the assembly together. This of course leads to moisture getting into the cheeks and spacer. Since the spacer is plywood and doesn't hold fasteners as well as most solid lumbers, the holes "egg" out, rot gets started and the down hill slide is on.

Rudder blades of solid lumber are best made of vertical strip plank construction, with alternating grains in each strip. Edge glued and fastened, these perform quite well, with much less movement, cupping, distortion, etc. Given a sheathing of cloth, much more stable. A clear finish requires 4 ounce, with 6 ounce being just barely visible at 4' away in very bright light. Neither of these weights of fabric will provide a lot of abrasion protection, but better then none. I'd use a couple layers of 6 ounce as a minimum, 8 ounce would be better, but it wouldn't be a bright finish. Only 4 ounce or lighter will be truly invisible.

Cheeks, particularly hardwood versions, are very prone to moisture gain movement. Inserting a sheet of Teflon or other slippery (HDPE, etc.), inert material between the cheeks and the blade can help tremendously, especially if a tight fit is desired.

Teak is a preferred blade and cheek material because it's much more stable then other hardwoods when wet. This could be said of most of the oily woods I guess.

Personally I use pure GRP or form cored laminates for blades, aluminum or stainless for cheeks, bush out the pivot, etc. so no issues can result. The same with center or daggerboards.

In your case Eagle Boats, I'd embalm the plywood with epoxy, sheath it and ditto the cheeks and blade. I'd also reinforce the leading edge with metal or my favorite a epoxy soaked section of double braid, let into a cove, carved into the leading edge. This takes all sorts of abuse, without injury to the surrounding wood and looks pretty cool. I'd also bond all fasteners and pivot hole, even if they are bushed with an inert material. I don't know how we manage to ding up the trailing edge of blades, but it happens quite often, as if we sail backwards, blindfolded a lot. This is another area that could use some metal reinforcement (so you can maintain a crisp edge).

 

Well, PAR, I admit my last payment was a little slow in getting out. I've got other forum members besides you to consider.
True, rudders suffer some bad punishment. I glassed mine, over 1 1/2" of sculpted okoume, single layer 10 oz, double taped on the leading edge, and no glass at all above the waterline. However, the mechanism is a back-latching tiller that removes out of the slot when raised high enough. The rudder has no cheeks, as these are on the tiller. An adjustable bolt maintains exactly the right tightness by pinching the rudder head. I like this system very much as it trailers well by slipping off and there are no rudder cheeks to worry about, the tiller cheeks being high and dry. It is not as strong as a rudder with cheeks, admittedly, but being maybe 5" fore and aft, the rudder head is quite strong. I can't see how glassing it would offer much more in terms of strength, and the only point of wear is the area swept by the tiller cheeks, easily adjusted, and easy to re-surface if ever need be.
On the other hand, I baby my boat. I am not building a boat that will potentially be used hard by people who sail backwards. Your points make sense if the boat is likely to be treated like most people treat things nowadays.
A good article in WoodenBoat mag described a proper cheek rudder build having two layers of cloth throughout over a ply lamination. The boat shown was not a dry-sailed boat. I think your description of the ideal construction was very similar to that.

Alan

 

"Invisible" fibreglass

Its only invisible IF the wetting out is very thorough. and it shows up all the faults in the timber underneath. If you want a quality wood finish on *this* hull, the work would be horrific. It would be better to cover the old ply with a new ply veneer ( or teak strips) and then glass it over

Good luck -

 

Par,

Great little tidbit about the double-braid. Rereading your post, you let it into a cove, so it not buried too deeply. (?) Do fill the weave, or glass over it with some light cloth?

Back to the original post,

I don't think I can add more to what has already been said other than, I don't think a bright finish is in store for this boat. I think that is perfect candidate for learning to epoxy and glass. It should look nice with a good painted surface when all done.

 

It's not that uncommon a trick (double braid, leading edge), I've seen it for many years. The cove keeps it in alignment on the edge and cradles it a touch, but not much more. Fill the weave and you don't need fabric, though if you plan ahead (right) and are sheathing the sides, then this is a nice place to easily terminate the fabric. You just finish out the leading edge fairing as you take care of the edges of the fabric on the sides in the same process.