Plywood Tank Resto: Recombobulating my 200

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Well, things keep getting more complicated with this @$%^#. I seriously considered the firewood route when I realized I had to tear the front off. Considered it again when I realized the bottom of the tank is warped about 1/4". The challenge of wood is that it moves!!! Future designs will definitely keep this fact in mind and try less to make a rigid structure that will be F***ed if anything warps. Anyway, After mulling over carefully the idear of burning this tank and building a 66"x36"x36" instead. I jammed a diagonal brace into the tank and began fabbing the new front. I think, likely, when I take the brace out after the glue dries, the bottom will bow again a bit, but my plan is to fiberglass the tank, then put the window in with high strength structural silicone, and put the brace back in to flatten the bottom while the silicone cures. The cured silicone and the glass as a structural element should keep the bottom flat until I get it filled. The water in the tank will be 2000lbs of force holding the bottom flat so I should be golden as long as I get it to lie flat until then. I really didn't want to leave it bowed, glue the glass in, then fill it and have all that weight trying to force it flat, pulling on the window seal.

Anyway, pics = 1000 words

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Still looking rough, but it's taking shape. Plan is to fiberglass the entire interior of the tank, and also the front, wrapping around the sides and blending out. I'll sand it flat on the front and finish it with either truck bed liner or gelcoat spray, if I dare spray epoxy.
 
Plugged all the holes in the tank

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Did some sanding and other cleanup, threw a quick primer guide coat on all the edges and fillets. Gotta dou a few more hours of sanding before starting to epoxy.

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Heading to Vancouver tomorrow... gonna pick up all the polymer supplies I need to get going on the sealing and so on.
 
stevenhman said:
Lookin good! Are you gonna glass the back where the wood hole plugs are?
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Yeah. I'm a bit anal about things. Last go around I filled and sanded the whole outside of the tank and coated the back with gelcoat. This time I'm planning to glass the entier inside, and the front, possibly the back and sides. At the very least I'll glass over where I've filled the holes, though it really won't be a structural thing as much as a cosmetic one. I may glass the bottom of the tank too, given that it looks like it got a little wet during the years this tank was running.
 
Did some actual glassing this weekend. I started by coating the whole inside of the tank with a film of black tinted epoxy just so I could be sure I'd sanded out all the imperfections and so I'd have a uniform colored surface to lay my glass over. Then did one 36"x50" sheet of glass for the whole back of the tank, wrapping around the sides slightly. Next I'll do two more sheets - one for each side, and one for the bottom and see where that leaves me for epoxy, glass, and patience. This glass cloth isn't as difficult to get around corners as I feared it might be, so I might not have to do a lot of fiddling with the seams.

Anyway, I also mixed up some black tinted epoxy with some cabosil and glass bubbles and filled the whole front. It's going to be a PITA to sand, but I think it's going to look sweeeeeeeeeet with a nice flat, smooth plastic front. After the front is filled and sanded flat I'm going to glass over it as well. I am extreeeeeemely tempted to buy a couple yards of carbon fiber cloth and laminate the front with that, then cover it with a slightly tinted flood coat so the tank looks black unless you look at it really closely and see the C-F weave. Will see how ambitious I get with that idea.

Anyway this is where we stand:

200-BackglassedFrontfilled.jpg
 
It's system three silvertip epoxy. Almost no smell actually. I'm pretty happy with it so far. I do still prefer Polyester to work with but this stuff is pretty nice. Not too expensive either at about $40/l
 
Excellent work!

What was your filet material? I've never done fiberglass before so I did a test piece and was a bit concerned that my corners have air bubbles.
 
If you decide you don't want to spend the money on carbon fiber a friend of mine used a burlap sack to match his fenders to his CF hood. It looked pretty flawless. If you lay the base color then stretch the burlap over it and spray the next color it looks like a weave.
 
stevenhman said:
Excellent work!

What was your filet material? I've never done fiberglass before so I did a test piece and was a bit concerned that my corners have air bubbles.
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I used drywall spackle for the fillets. Now, I'm certain not everyone will agree with this as a good idea, but I did have several reasons:

1) The fillet does not contribute any strength in and of itself, really it only provides a form for the glass to lay on.
2) If the plaster gets wet and loses all integrity, the glass will hold it's shape, and I don't care if the fillet dissolves out completely. In this situation I'd have other worries anyway.
3) Drywall plaster is a dream to sand when compared with epoxy based fairing materials.

Anyway, making fiberglass lay nicely into corners is every boat builder's challenge, and there's no magic solution except to plan your layups carefully and work in relatively small sections. Using some resin with a long pot life doesn't hurt either. Air bubbles need to be sanded out and redone, as they are an easy leak path, even if they look watertight. I also took a router and some heavy handed sanding to all outside corners to help the glass conform to those as well. I think the cloth is 6oz cloth which is pretty light, which also makes corners easier.
 
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