Can Be a Big Job - Support Board

Freesail99 · #1 05-12-2007

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 ?

Thanks,
Paul

sailingdog · #2 05-12-2007

Freesail-

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.

hellosailor · #3 05-12-2007

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.

Freesail99 · #4 05-13-2007

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.

Freesail99 · #5 05-20-2007

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 ?

hellosailor · #6 05-20-2007

I don't know about the other guys but now I'm totally confused. What's the big nut and bolt about?

Freesail99 · #7 05-20-2007

That is the nut that holds the rudder shaft. About 14 inches below that would be the packing.

DeepFrz · #8 05-20-2007

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.

Freesail99 · #9 05-20-2007

Quote:

Originally Posted by DeepFrz

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.

That is my plan. I was even to drill some holes and fill the boards with epoxy to add strenth between the boards. Thanks

hellosailor · #10 05-20-2007

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.)