Using Ethylene Glycol on rot damaged GRP covered stringers and bulkheads to arrest further decay

That simply does not work that explains why nobody suggested it . For rotting the wood needs oxygen and a humidity above 20%. At that level of humidity no epoxy will glue or even penetrate in the pores for a mechanical key. There are very DIY solutions that none pro would use and that will be the object of my next post.

 

Photos.

I took a sample (hole just beneath the seat post) about 1 metre behind the forward bulkhead. Some rot in the centre of the ply but firm on either side. Significantly less damage than the front.

This is in the cabin looking back to the forward bulkhead. The unfinished hole at the bottom of the bulkhead was quite wet so I didn’t finish drilling it. (Hole in the floor is a drain hole)

This was the sample at the top of the forward bulkhead. Damp but solid.

This was the sample on the left of the cabin photo above in the stringer

the front damage I think is caused by rainwater. There doesn’t appear to be any delamination of glass and wood.

I havnt Got any good photos of the rear bulkhead / stringers however when I drilled into them they appear moist yet solid. I suspect the rear damage may be seawater.


Martin, could you post a few photos of the damaged areas on your boat please?

 

the glass thickness looks like it would be plenty strong enough without the timber. i pulled the floor up in an old pongrass a while back, it had glass box section stringers and the walls were a lot thinner than the glass in your pics. is the transom in good condition.

 

i would imagine the build quality would have to be pretty good to carry the yamaha name.

 

Good transom? THAT is the big question. Again the fibreglass guys recon it seems good but I have to lift the engine off maybe this weekend so will check out around the mounting holes when I do.

 

Yeah that was my thinking about the glass too. They’ve gone to a reasonable amount of trouble with the layers of glass.

 

wasn't the Southwind a Yamaha product ?

 

if you shake the tilted outboard as hard as you can with no flex in the transom then its all good. can still have crook areas around bungs and any screws though.

 

Yep it was. I think they shut down in 2003 or 2004 the Southern Star started producing with their design after that. I think they lasted about 5 years.

 

Noone suggested it because it is a bad idea. First of all, you cannot inject flock. Second of all; injecting epoxy can only seal in the rot.

I had people recommend fixing a balsa core rot this way, but I was unwilling to trust the boat in 2M seas.

I have seen people cut the stringer top off and hog out rot. Or cover the entire stringer and accept the rot, but it must beisolated from the hull if a cored hull a/o transom, etc. And the repair is structural so needs lotsa epoxy n glass.

 

check at the intersections of the stringer if motor mounts are good; they used poly so water can run all over

the stringers are not good enough without the lumber

 

I think it has a small amount of flex (glass guys did what u suggested). Will have a closer look with the engine up. It’s been suggested by done to put a stainless backing plate on the rear of the transom as a precaution however the general consensus from the professionals is that it’s not bad

 

Hey fallguy do u know the intervals of these boats?

 

no

 

intervals? You mean scantlings?

No.

If you have rotting stringers; it is fallacy to suggest the stringer core is not structural. The layup around them was so light water is running all over the boat.

of course the stringer core is structural