Here are pictures of how I redid MADLEE's bilge. Two 3/4" layers of plywood were chiseled out and replaced with three separate layers of fiberglass mat and roving per Catalina's spec. laying it flat on the bottom and running it up the bilge sides 6". To this, I added 18oz biaxial cloth (+-45) to: improve strength up the sides of the bilge, build up depth in the bilge floor and improve finished smoothness overall. I also put in two separate layers of 1/2" G-10 board. Since full length pieces were not possible to lay in, I staggered the layer's joints and set them with West System epoxy thickened w/ 406 adhesive filler. Sanded constantly to ensure good bond with succesive layers. Overcoated all with Interprotect 2000. The four "middle" bolts needed an extra block of G-10 so the washers would have sufficient flat space to bear the weight. Mast compression post will be similar, using 3/4" G-10. Still not done yet!!!!
Catalina bilge plywood repair
- Thread starter rbmcintire
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Thanks, Bad. The boat splashed Wed. and nary a creak or groan. Solid, I'm happy with the result. Now it's back to: compression post support, engine re-connect/ alignment and doing the mast rigging and rewiring. Nice part is, now I'm hooked up to dock power and can have air conditioning if needed. Man, has it been brutal with the early seasonal heat! 
Just completed this same repair on our C27. Found a solid piece of what appears to be teak in the bilge. Wasn't rotted, just very wet. Removed the pan material and let it dry for 5 weeks. Layed in the glass and used the G10 around the keel bolts. Splashed last week, no more worries.
Wow, that looks like a lot of work! I remember reading the Catalina specs on that repair method, but I don't remember the use of G-10. Is this a marine grade plywood, or is it a plastic composite? I'm assuming its rot-proof ? I'm hoping that if I can get my bilge dry by replacing the prop shaft seal with a dripless one in my next haulout, & I can avoid this plywood rot problem.
I chose the G-10 to build up stacked layers for the mast compression post. I'd seen online, another owner using epoxy encapsulated white oak, but I decided I didn't want to use wood. For the bilge, the three layers of roving and mat per Catalina spec. doesn't build up the bilge floor to the original thickness. Removing two 3/4" layers of plywood plus the laminate and factory filler covering them is a lot of material. So I built up another 1" using two layers of 1/2" G-10 and now the keel bolts are on really solid bearing. The G-10 is a fiber/epoxy board formed under high pressure, virtually impervious to water and has a compressive strength of something like 60,000lbs. I got two 2' x 3' sheets, one 1/2" and one 3/4", through McMaster Carr for about $400. I will agree, this is a lot of work and the only way to change that is to pay somebody else to do it, but I think I saved thousand$$$. This is the first time I ever mixed a batch of epoxy and the bonus is now I can do all types of repairs with it, if necessary.
Nice job, I like your idea of using G-10 under the compression post. I've seen the DYI website you're referring to where the guy used white oak.
I have to do the same, just been putting it off for the last few years...sigh.
Sooner or later.
Don't forget some pics when you're done with the new post base.
Chris
I have to do the same, just been putting it off for the last few years...sigh.
Sooner or later.
Don't forget some pics when you're done with the new post base.
Chris
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