Replacing Cockpit Floor 241/240 Weekender/Offshore

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DennisG01

GreatGrady Captain
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Location
Allentown, PA & Friendship, ME
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Offshore
So... I've started to tackle "the project". Bought the boat, with my brother, near the end of the season and knew the floor was soft so I had planned on doing this over the winter. I built a wooden structure off the aft corners so that I could shrink wrap the boat "high". That way I would have easy entrance into the boat during the winter and I was able to use 4'x3' shrink door. I put a small space heater in there and it's actually been quite cozy! So far, I've got the floor skinned and all of the plywood (was in squares) removed. I also tore into the bulkhead that runs behind where an aux fuel tank would be and I'll rebuild that, as well. I'm going to leave everything open till the Spring to make sure anything that is still wet dries out nicely.

I found that a shingle removal tool worked great for separating the top skin from the plywood. The Wonderbar worked well to to do the initial loosening, but the added weight and length of the shingle tool was much better for the bulk of the work. The oscillating tool was great to use for dong the initial cut through the top skin as it doesn't really make any dust like a rotary tool (circ saw), although not as fast as a circ saw. I initially used a straight cut-off blade (in picture) to remove the remaining wood, but I found that the "stiff scraper" attachment worked better for helping to separate the plywood from the bottom skin.





 
what are you going back with, wood? coosa? be careful when doing the prep sanding/grinding on the inside skin as its very thin....you will probably burn through a few spots....may need a layer or two of glass before putting in your new core......
 
I'll probably just use 1/2" marine ply - strictly for the cost. Although, I don't mind the extra weight that the ply will offer, as well. I'll give it a good coat before even installing it. Yup - that bottom skin is just a single layer of thin glass. I was able to get it pretty clean with just the scraper. Any wood that is left is paper thin - the epoxy should soak right through it. Not even sure if I have to do any sanding there. Besides, I don't think that bottom layer is adding any strength. It was likely just used to hold the plywood in place while the top skin and ply set up. My concern, though, with reinstalling is that I'm doing this right side up on an uneven surface (thin bottom glass). If I add any more glass to the bottom, it might make it even harder to have the ply lay flat and true. Originally, Grady would have built this upside down and laid the ply on top of the already flat top skin. I'm open to suggestions!
 
I dont think one layer of biax is going to inhibit anything...after being wet out it's less than 1/16 of an inch......you will need some type of support when you put the wood back in and try and clamp it or add weights to bond it well.....if the bottom is too weak and flimsy, it will bow with pressure and then you'll have areas with no contact.....by sanding the old wood residue/skin, you will ensure a better bond and it will give the the right depth clearance for the new core and extra layer of glass....I would not bond it to that remaining onion skin of wood....it will most likely fail at those spots after some use.....
 
That bottom skin is already so thin that it's not flat - it follows, to some extent, the foam underneath. Not sure if I can add a new layer and expect it to be straight. I was planning on using thickened epoxy (like buttering a tile) there anyways, but I suppose another layer won't hurt. If some of It never sticks to the ply, I don't think it will be much of a problem since that bottom layer isn't structural.
 
DennisG01 said:
That bottom skin is already so thin that it's not flat - it follows, to some extent, the foam underneath. Not sure if I can add a new layer and expect it to be straight. I was planning on using thickened epoxy (like buttering a tile) there anyways, but I suppose another layer won't hurt. If some of It never sticks to the ply, I don't think it will be much of a problem since that bottom layer isn't structural.
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In actuality, both the bottom layer and top layer/skin make it structural when dealing with a core.....the core basically does nothing ..it just spreads the skins apart making them a taller beam........its the inner and outer skins that create the stiffness and carry the load.......without the bottom, you'd be relying on the core to do the work....plywood can take some of that by itself as its designed to...but if it were a foam core or balsa, it would not work well at all without a good bottom skin.
 
I understand the I-beam effect and that the glass, itself, is the main structure. I'm just surprised to hear that such a thin layer adds any real strength. But adding a quick layer can't hurt. Each side of the floor is roughly 2-1/2'x7' (just guessing on that). I was originally thinking of laying the plywood down in several pieces. But with the bottom being so uneven (too bad I couldn't construct this the way it originally was!) maybe I should lay one big piece down - at least to cover the majority of the floor area in one shot (per side, anyways). At least that way the floor will be pretty close, if not completely, flat. Drill a bunch of holes in the sheet, of course, and just butter that bottom layer up with thickened epoxy, after wetting it out. If I use slow hardener, with Spring temperatures, I think that should be OK?
 
Being that the surface is uneven, I'm almost tempted to suggest putting it back in pieces/squares like original with thickened resin......it may be easier to get better contact than a whole piece.....then put the outer skin back on taking care to get it as flat and in perfect contact as possible....
usually, folks cut out the entire floor, core out the exposed/finished skin, then re-core on a nice flat surface.........
well, you can always cut out the one piece and dry fit it....if its pretty even and makes good contact without rocking, go for it........if not, cut it into squares and keep going....no real negative to it other than some extra time...
 
richie rich said:
Being that the surface is uneven, I'm almost tempted to suggest putting it back in pieces/squares like original with thickened resin......it may be easier to get better contact than a whole piece.....then put the outer skin back on taking care to get it as flat and in perfect contact as possible....
usually, folks cut out the entire floor, core out the exposed/finished skin, then re-core on a nice flat surface.........
well, you can always cut out the one piece and dry fit it....if its pretty even and makes good contact without rocking, go for it........if not, cut it into squares and keep going....no real negative to it other than some extra time...
Click to expand...

Hmmm. That's a good thought with using smaller pieces of ply. I've been anticipating trying to lay down the plywood in such a manner as to make sure it's perfectly flat. But, it would certainly be easier to adjust the top skin to be level and flat via thickened resin than trying to make the plywood level and flat. After laying the plywood pieces in, I suppose I could even come back and fill the low spots much like drywall joints.

For future reference, can you explain more regarding "usually, folkd cut..."? Are you saying there was a better way for me to do this (on the trailer in a driveway)?

The largest single application of fiberglassing/wood coring I've done is about 5 square feet (underside of my Sundancer's anchor locker deck) . I don't recall exactly how much I used. Going with smaller pieces of plywood this isn't as important, but how much resin do you think I might use for a 2-1/2'x7' area?
 
When i did the searay i got 5 gallons of epoxy. It's hard to say cause u have no idea how much the plywood will soak up. Plus since your planning on using epoxy to also fill in low area's. Me personally i tend to over buy...lol I hate running out while in the middle of a project. Plus epoxy doesn't have a shelf life so if u have extra your set for another project or u could always sell the unused epoxy on craigs list. I got all my supplies from us composite the more u buy the cheaper it is.
 
DennisG01 said:
richie rich said:
Being that the surface is uneven, I'm almost tempted to suggest putting it back in pieces/squares like original with thickened resin......it may be easier to get better contact than a whole piece.....then put the outer skin back on taking care to get it as flat and in perfect contact as possible....
usually, folks cut out the entire floor, core out the exposed/finished skin, then re-core on a nice flat surface.........
well, you can always cut out the one piece and dry fit it....if its pretty even and makes good contact without rocking, go for it........if not, cut it into squares and keep going....no real negative to it other than some extra time...
Click to expand...

Hmmm. That's a good thought with using smaller pieces of ply. I've been anticipating trying to lay down the plywood in such a manner as to make sure it's perfectly flat. But, it would certainly be easier to adjust the top skin to be level and flat via thickened resin than trying to make the plywood level and flat. After laying the plywood pieces in, I suppose I could even come back and fill the low spots much like drywall joints.

For future reference, can you explain more regarding "usually, folkd cut..."? Are you saying there was a better way for me to do this (on the trailer in a driveway)?
The largest single application of fiberglassing/wood coring I've done is about 5 square feet (underside of my Sundancer's anchor locker deck) . I don't recall exactly how much I used. Going with smaller pieces of plywood this isn't as important, but how much resin do you think I might use for a 2-1/2'x7' area?
Click to expand...


OK...usually, when a deck is being replaced, the entire deck is removed, ie, both bottom and top skin and core....this is the first I've seen where the outer skin was removed leaving the core and inner skin in place.......if you cut all the way thru and remove everything down to the stringers, you now can strip the inner or under skin.....remove the wood core......then just leave the outer skin with the non skid in tact......folks would re-core with plywood, balsa or Corecell type foam core....and then add a few layers of glass on the bottom side to complete the job.......putting the deck back in place would be laying down thickened epoxy and bedding the complete laminate back in place.......then just fairing the cut joint to make it look good.......peeling just the top off as you did is a first in my book.....doen't mean its wrong or anything...just a different approach......it should work fine...remember, its just glass and resin and putty....a grinder will take care of everything if something goes bad.....keep plugging forward...
 
OK, gotcha - I understand. In my case, I really didn't care about the top skin since the non-skid isn't so much "non-skid" anymore after 32 years of being worn down (planning on painting with non-skid additive). Originally, I also had only planned on removing just the rotten section of plywood. Turns out the entire floor was wet, although only about 50% percent was actually rotten. Realistically, I could of just left the good stuff dry out, but once I started it wasn't a whole lot more work to remove it all and in the end I'll be glad I did.

There's also no outboard (along the hull side) stringer - as the cockpit floor liner was all one piece and continues up the hull side. I was surprised to see this on a 1982 boat. I was also thinking of reinforcing the transition in the floor liner that is between the vertical section (hull side) and actual floor - using your idea of strengthening the aptly-named onion skin :D and also further reinforcing that transition from horizontal to vertical.

I also need to rebuild the area where the stern drive engine used to be and create an access hatch. Thinking of either using the existing aux-tank lid as a mold (and then mounting it port-to-starboard) if the size will work or just make a new lid with my own form. I also would like to build some type of undermount water drain along the edges of the hatches to keep the bilge as dry as possible. Thinking of FRP L-channel mounted around the inner perimeter of hatch opening and then drain to a new thru-hull on the hull side, above the waterline.

With cold weather here, I'm not planning on starting any glassing until the Spring. I was using the oil space heater to keep things comfortable (and unfreze the floor) but I imagine it isn't all that inexpensive to heat an area whose only insulation is the shrink wrap. On the plus side, I've got lot's of time to think about what to do. On the negative side... I've got lot's of time to think about what to do!
 
John, I remember that you recommended US Comp in another thread (and Robert, as well?). I checked them out and even at the prices I can buy the West System for (which I usually use), depending on what the shipping charges are from US Comp, the prices should be nice from US Comp. I'll probably get 2 or 3 gallons to start with.

Did you still want to see where to access the fish box drains?
 
Here's a couple pics, John. I had originally thought that the deck plate was original, but since the thru-hulls are bronze, it appears someone already changed these out somewhere along the way and put in the deck plates. In the "floor" picture, I cut away some of that "onion skin" and there is very little foam there which allows access to the outboard compartment drain and thru-hull. I can physically reach the thru-hull through both the deck plate and the hole. In feeling the onion skin, it appears the foam is packed tighter against the inboard compartment. Directly below the outboard drain is a plastic T-fitting to tie the two compartments together. Looks like I should tighten up that hose a little better!



 
Is that thru hull in the last picture new? It looks like the original plastic.....if so, I would change them out....they get very brittle when old and can break easily....happened to me twice...
 
Is it the T-fitting underneath the outboard compartment drain or the fitting for the inboard compartment drain? Maybe I can get a camera in there - or maybe stop by sometime?
 
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