SailNet is a forum community dedicated to Sailing enthusiasts. Come join the discussion about sailing, modifications, classifieds, troubleshooting, repairs, reviews, maintenance, and more!
I am not sure of the proper name for it, but the board, which in my case is 2 layers of 3/4 plus 1 layer of 1/2 plywood laminated together has some rot. This board is what the rudder shaft connects to and hangs from. Now here is the problem if I replace entire board I will need to remove a wall in the aft bearth. Making everything "pretty" again will take so time. If I do this, I will replace the 2 x 10 inch laminated plywood board with an engineried laminated beam. Much stronger.
Now the rot as far as I can tell isn't a lot but it is their. I tapped and used a screwdriver into the wood looking for soft spots. I found a couple of them. I was also thinking that I could set the depth on a cirular saw and cut away the top layer of the rotted area and epoxy back in a new peice of marine ply. I could even add a peice of 1/4 Alum. Plate to the top of the beam, spreading out the load. What do you guys think ?
it would help a lot if you said what kind of boat this is on and if you posted a photo of the part.
An engineered laminated beam may be much stronger, but most aren't designed to be used in wet environments, and if it is, it may delaminate more quickly than the plywood did.
Paul, even a fuzzy cell phone photo would help. It sounds like you are talking about a skeg-hung rudder, meaning the from edge of the rudder is hinged onto something in front of it, another board or the stern of the boat.
Depending on the damage, it is possible to dry wood out and inject epoxy penetrant to stregnthen it, but if the wood is damp and the damage is large you'd probably be safer replacing a critical part--like a rudder mount.
"Marine" materials are best for this, either marine ply (which is particularly dense and solid with no voids) or fiberglass are typical. Aluminum plates would be a bad choice since aluminum easily has galvanic problems in the wet.
I will take some pictures today, as I didn't have my camera yesterday. This is the board the rudder shaft hangs from. In my boat this board is 2 x 10 x 79. it is fiberglass ( tabbed ) into the stern on 4 sides. I will post some pictures late this afternoon, thanks.
I was back at the boat, the damaged area looks to be no more then 5 or 6 inches from the rudder shaft.
The wood chips in the picture were made by me, looking for the rotten area. I also looked below and saw no problems at all. It appears the entire rotted area would be no more the 10 x 8 inches at the most.
So my question is can I cut away the small area and epoxy back in a new peice of plywood ?
I don't see any reason that you couldn't cut out the rotted area and scarf in a piece of wood to replace the area cut out. If I were doing it I would sand everything back to good wood and then coat the wood with several coats of epoxy resin, perhaps even adding several layers of fiberglass cloth to the top. Make sure there is no rot back where the shelf joins the bulkhead.
I don't see any reason that you couldn't cut out the rotted area and scarf in a piece of wood to replace the area cut out. If I were doing it I would sand everything back to good wood and then coat the wood with several coats of epoxy resin, perhaps even adding several layers of fiberglass cloth to the top. Make sure there is no rot back where the shelf joins the bulkhead.
DeepFrz, when you say "scarf in"...simply cutting a piece out of dropping a new piece in, which is simply a butt joint on all four sides, might or might not do--depending on the strains and exactly what this board is. (Which I confess I still have no real grasp of at this point.)
Just how are you suggesting he scarf it in??? (Which usually means at least a 45 degree angle on all joint surfaces, to me.)
I would try and repair the wood using thickened epoxy and then add an aluminum or stainless steel plate over the whole thing and have the bolt go through the plate. Then bolt/screw the plate down. That will spread the load out a lot more than just repairing the wood will.
I just don't know if you've got enough thread left on the rudder stock bolt to do this... conversely, you could thin the wood a bit if you're going to be using a metal plate to spread the load out.... and that would give you the room to fit the plate. YMMV.
There seems to be enough room on the depth of the shaft to add a 1/8 maybe 1/4 inch metal plate to the top of the board. That was my original idea of how to fix it. maybe 24 to 36 inches long.
I posted some pictures of the problem area which was about 4 to 5 inches from the shaft. So I cut out the top layer of 3/4 plywood. A piece about 8 x 30 inches and screwed and epoxied in a new piece of marine plywood. I then used thicken epoxy with some 6.5 oz fiberglass cloth and covered both layers of the 3/4 plywood. I encapsulated the wood. I also replace the 4 inch plate in the cockpit seat where the leak came from. It was where the emergency rudder would connect to the rudder shaft.
it would help a lot if you said what kind of boat this is on and if you posted a photo of the part.
An engineered laminated beam may be much stronger, but most aren't designed to be used in wet environments, and if it is, it may delaminate more quickly than the plywood did.
I would get a 2" x 4" piece of heavy-wall channel iron, bore an appropriate hole in it, grind it clean, prime it with a couple of coats of Interlux 2000 barrier coat, dig out the rotted wood and fill it with West epoxy and sawdust, install the channel face down secured only with an ample coat of 3M 5200, then paint it all a nice white so you can easily see when the iron starts to rust. The channel should be about 18" to 24" to disperse the load and make max use of the 5200 bonding, but a foot might work as well.
This will give you plenty of time to consider tearing the whole aft section apart and laminating in another full beam. You may never have to.
Hawk
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Related Threads
?
?
?
?
?
SailNet Community
1.7M posts
173.8K members
Since 1990
A forum community dedicated to Sailing, boating, cruising, racing & chartering. Come join the discussion about sailing, destinations, maintenance, repairs, navigation, electronics, classifieds and more