Need to stiffen underside of cockpit floor

[Seattle Scott]

which appears to have had prior repair on the underside. I get some flex in the floor when I step down from the deck and there is dry crackling sound when I shift my weight from foot to foot. I have drilled small holes in the affected area ( which is about 1 foot x 2 foot) every couple of inches, about 1/2 way through the wood cored floor and injected epoxy, but symptom still exists. I would like to repair/strengthen from the underside and wonder what is the technique for adding laminate to the underside of a horizontal surface, like doing glass work on a ceiling, where gravity will try to deposit everying onto the engine under the cockpit. What about glassing up a 1/4 inch thick plywood or aluminum piece and while wet, bolting it to the underside of the floor to cure, then remove and fill bolt holes? I know I will still need to fill the voids in the existing floor and in the gaps between the floor and the bolt-on sheet, by more injecting from the topside. It seems an aluminum sheet would prevent drilling all the way thru. Also I am trying to avoid stripping off the cockpit floor skin since my past glass work is pretty rough in appearance.Any thoughts?

 

[Ed Schenck]

Ahead of the pedestal?

That is one H37C problem I have not had. Maybe the only one. But I think I like your plywood sheet idea. I would use 1/2" cheap construction plywood. If you mean the cockpit sole ahead of the pedestal that is a fairly large area. Cut a cardboard template to fit most of that area. Then transfer to the plywood. Now coat both sides of the plywood with West System. Drill enough holes to screw it to the underneath of the sole. Use screws just long enough to hold it in place. Coat the plywood with a peanut butter mix of West System within about 2" of the edges. Screw it in place. Once the resin sets you should have one stiff sole. I don't think 1/4" is strong enough but it might be if soaked with resin on both sides before you install. Good luck.

 

[scott]

Yep, affected area is most forward

one foot of cockpit sole. There are signs of patching to the underside of this area and not a very good job which is easy to understand given the difficulty of laying up cloth to the underside of a horizontal surface without good access to boot.

 

[Ed Schenck]

Without good access?

Scott, is your boat old enough that it does not have the access door from the quarterberth? Access to the bottom of the cockpit sole is not that difficult from the q-berth IF you have that door. My '79 did NOT have it. Now it does.

 

[scott]

Ed, mine's an '85 w/the door

access from the quarter berth. OK, I guess that is good access in "boatspeak".

 

[Ed A]

some good ideas, but

I would suggest using exterior grade plywood. it has waterproof glue. It is a little more complex but this is the perfect job for vacum bagging. you can hold the material in place with the wood with the plactic pre-cut and then suck out the air. you get a great job and no more holes.but you need a small vacum pump and a little practice to get it right.

 

[Seattle Scott]

Tampa Ed, can you give me more

detail, or let me practice on your boat?

 

[Ron5058]

Photo Forum Project

There was a photo forum project similar to what you want to do. Unfortunately there weren't any pics of the work in progress. It was by David Underwood. You might see if you can contact him for more detail

 

[Ed A]

Scott, I would let you but my floor is good!

I am not the guy to teach it, but it amounts to creating a seal arround the patch with what ever will make it stick. i have used duct tape for the plastic. wet out the area you plan to repair being careful not wet the area you want to tape the plastic. perferate some plastic tubing and arrange it so you can suck out air to a vacum pump. precoat the core material you plan to use ( ac exterior plywood works good)with thickend epoxy. wet out the fiberglass cloth and lay it on the plastic put the board on top and put some thick epoxy on it so it will fill voids. push the whole mess up to the floor of the cockpit. tape it in place, and prop up the center with what ever will hold it. then crank up the vacum pump. It will suck the air out fill the voids and repair the floor in one shot. Im not an expert but it will work and you dont have to worry about too much finishing on the top of the engine room. Im sure there are west epoxy instructions available.you would have to work fast once you mixed the resin but with a little help and care not to make a mess it shoud be fine. Let it dry overnite and remove the plastic sheet and the air tubes and your good to go.sounds easy huh! makes a strong and very good patch and just hang some soundproofing and go sailing. remember if your glassing in wood to be sure its waterproof glue, andnever try to get anything to stick to pressure treated wook. It just wont stay on!