I asked some folks on the woodenboat forum, on the "outrigger and proa thread" what might be done to avoid this problem. Someone suggested (Gary Dierking perhaps?) plywood sandwiched between two aluminum plates. He also suggested plywood made of a stiffer type of wood. Can't remember what type it was and I don't have access to the internet at the moment to check. My solution varies only because I am limited on resources. I had to make do with what I currently have on hand. I only had enough aluminum left over to plate the one side. I think it should work though.
This is an 1/8" thick aluminum plate fastened with 13 epoxy bonded wood screws into a plywood base. As well as being attached with screws, for what it's worth, the aluminum plate is also glued with epoxy to the wood. Not sure how strong the bond will be to the aluminum, but at the very least it provides waterproofing for the wood between the plate and the plywood. Then all the rest of the wood was coated with epoxy resin, allowed to soak in and reapplied again while still uncured, so as to soak up as much of the stuff as possible. This should hopefully make the wood much less penetrable by water. The whole thing feels pretty strong. All the rest of the boat is out in town so I have to wait till we go out again in September to get it all assembled.
For comparison, I've attached here pictures of the original assembly (with the rudder attached) as well as a picture of the new one I've constructed.
Yes! I have (or seem to) this very same problem on my outrigger. The problem appears when I run downwind in waves that envelope my hull (small waves but big ones for my 16'er -- 3-4 footers). When the rudder is buried at the wave crest I have barely enough power to keep the boat from turning -- a run down wind in choppy seas in constant fear of broaching. Was your experience a little like this? I must try something like that. I have a pretty stiff piece of hardwood ply as the cheek-piece made for this problem, but not stiff enough.
ReplyDeleteYou mentioned you had the spongy rudder problem when running before the wind and in waves that enveloped your hull. I wonder if we have different problems between us... though your description of the bendy cheek piece sounds pretty much the same. Hmmm. Anyway, on our maiden voyage, we fought upwind almost the whole time so I can't say much what it would do in a situation similar to yours. Wish I had some downwind experience. My rudder problems typically happened though when Shan Skailyn was moving along at a stiff pace and I was making small steering adjustments. The force on one side or the other of the rudder would bend the whole assembly out to one side or the other to extreme angles. This happened both in bigger waves and on smooth waters, and on both tacks. It made it incredibly difficult to steer or even to maintain a coarse as I had to have quite the fine touch to get the thing to stay centered. There were the occasional times when the rudder would remain true (ie. straight down) but one small little movement would send the thing swinging way out. The problem didn't really happen when we were going slower. It only got hairy when moving along pretty good.
DeleteI took a picture of it happening... it was bad... wish I could post it, but remember my camera was stolen, and more devastatingly all the pictures on it. Ughhh. Still makes me sick to my stomach to think of what I lost there.