View Full Version : temporary patch, below the waterline over "vee" of hull
06-21-2008, 04:50 PM
Long story, but my (plywood/ glass) boat is on the beach above high tide line, now dry, with several large holes (6" (tall) x up to 3' long) along the "vee" / bottom of the hull in front of a small stubby mini-keel.
I need to do a quick temporary repair over these areas. I will be moving it a short distance to haul out at a boatyard
The "sides" of the hull, I will be able to easily patch with plywood and screws (with something like pl premium or roofing tar between ply and boat) , but I don't exactly know what to do over the "vee" of the hull...
The major challenge is that I will have to skid the boat back down to the water on planks and rollers (weight on undamaged mini-keel), but during the move, I can foresee possible damage to any lightweight patch over the holes nearby, specifically the "vee" of the hull...
basically, I will have 2 pieces of plywood "patch" coming together at the vee of the hull and I would like to form a watertight, semi-durable temporary patch between them...
A few options that I have thought about:
sail cloth, shrink wrap (2 layers dr shrink, then all the way up to waterline?), heavy tarp or some other "cloth" type covering stapled and glued to both pieces of ply
-lots of pl premium construction adhesive, possibly impregnating fiberglass cloth with this, or some other "cheap-ish" adhesive (any suggestions?)
-more expensive adhesives like 3m5200
I am officially not supposed to use any "chemicals (ie fiberglass resin, epoxy) where it is now, but...
- maybe just a piece of fiberglass tape over the seam if I could get away with it.
Any ideas, help will be VERY greatly appreciated.
06-21-2008, 06:03 PM
Do you have easy access from the inside of the hull? If so, think about jamming big blocks of closed cell foam down into the vee from the inside, held in place with wood members screwed or nailed as needed. Then just tack some tough nylon or poly cloth over the outside. Have pumps and pumpers at the ready.
06-21-2008, 07:04 PM
Wow, where to start?
I can only suggest to use the thickest ply that will take the curve of the planking, make the patches overlap the damage by 6"- 8" all around and at the chine, butt the patches (you may have to scribe and miter them to fit better for the strength you are looking for), load them up with the cheapest caulking in a tube available,and screw or through bolt well.
I wish you the best.
You are on your way to haul out, where repairs are to be done? I wouldn't bother wasting money, doing cheap jobs ,to get the boat there. Attach as much flotation as possible inside and out, move the boat, and get the repairs done properly.
06-22-2008, 07:38 AM
Is this boat really worthy of repair? Sounds pretty grave. You don't mention what caused the damage, if its rot related you may as well call for a dumpster and cut her up where she is.
06-23-2008, 04:16 AM
dredbob (or others)- suggestions on "then just tack some tough nylon or poly cloth over the outside"
what type of poly or cloth exactly would you suggest for this?
sb- to me it makes sense to move boat under its own power, rather than mostly sunk, it would be an expensive tow to say the least. I said "short distance" in original post, it would be a long distance under tow. (40 miles)
yes it is to me still very worthy of repair, not rot but damage from grounding, off anchor during storm. Not interested in telling the story until it's all over...
jackster- The "angle" of the chines coming together seems to me too wide (hope this make sense) to have much luck with a butt splice between the two patches)..
ANY other advice?
what material (think cloth, or similar) would you suggest for waterproofing between two ply patches coming down to a "vee" ?
specifically, how would you go about sealing/ attaching this material to plywood patch material and underlying ply/ glass hull?
06-23-2008, 05:54 AM
Could you use sheet steel bent over the V,protected with strips of 3/4" ply cut roughly to the right bevels, screwed to the hull?
You could use PL400 to glue the whole mess together and seal it as well.
It's available in really big tubes.
06-23-2008, 07:38 AM
Glad to see you have not given up, only you can decide if the effort to save the boat is worth it.
I think what you are saying is that the radius at the chine would leave a crescent shaped gap at the fwrd and aft end of the patches?
I would suggest that these could be filled with filler pieces and caulking just at the last 1" or so, that is just where the gaps are at the ends, letting the caulk dry as much as possible and maybe fastening with small gauge stuff (nails, screws?) for the temporary journey the the yard. None of the temp repairs need to be perfect, just tight enough to be stopped off with the caulking and only long enough to get you to the lift. And be able to stop enough water that the pump can keep up. All judgement calls and ones you must make.
Of course, this is all from my perspective from behind my computer, but am with you in spirit.
Good luck, keep your energy flowing and let us know what else we can do and what happens, I understand that it will take a while you are probably busy right now.
06-23-2008, 11:29 AM
My own fave - I keep some aboard any boat - is lead flashing. Goober it up with elephant s#!t (underwater setting epoxy) and tack in place. It's better to overlap short bits than allow any curves in the shape to force a fold. The lead is ductile enough that you really can hammer it around some astonishing shapes but the normal widths you can get it in may force a series of patches that run from one side to the other.
06-23-2008, 01:42 PM
If you're worried about damage to your temporary patch during the move back to the water, think about large soft rollers or a temporary cradle to keep the stress off the patch. Good luck.
06-23-2008, 01:46 PM
You don't even need soft rollers. Lay a path of planks or something like railway rails and use three or four nice round fence posts. If the boat's small enough that a couple of beefy boys can keep it level on the keel, this is an easy on the patch job.
06-23-2008, 02:42 PM
I think she is too heavy for soft rollers (9000 lbs) temporary bracing is in the works
I will be using planks and pipe rollers thanks for the suggestions,
this is how we got her above the tide line for repairs, hopefully this part will go fairly smoothly for getting her back out...
re: metal- thanks for the tips, I will go play around with some sheet steel (and lead if i can get my hands on some) and see how i might be able to make this work...
I am still thinking that cloth (of what type!?) might be my best bet... same concept as using sail cloth over the outside of a hole at sea, using water pressure against the hull to keep it from leaking.. (+ added security of extra ply and lots of 'goop')
07-03-2008, 04:32 PM
any suggestions for sealing rubber (ie truck tire innertube material) to fiberglass and wood?
I have most everything patched up with ply and pl premium construction adhesive, however, I still have one large ish hole to patch...
the plan is - rubber innertube stretched over hole (what I am asking about here is what adhesive you would suggest to make sure that this seal between the innertube and hull is going to be water tight), with plywood screwed over the rubber for support...
I think that water pressure will hold the (slightly stretched) rubber to the hull, but I would like to use some sort of "glue" just to make sure...
should I use more pl premium construction adhesive? silicone caulk? any other ideas?
07-03-2008, 05:44 PM
Gteat gobs of PL on plywood ought to do it, without the inner tube.
40 mi. I thought you were going across the harbour, long ride with no bottom. Giving advice that might drown you is not something that I am comfortable with, but ,I will give you some thoughts about the problem. There is a sponge rubber material, with a mesh core, that industry uses on the floor arround machinery, to lessen wear and tear on the worker's feet. I can't recall the trade name. Fit a piece of this over the hole, with 2' to spare in either direction. Cut strips of 3/4 plywood and roughly plank over the damage. Attach the plywood by drilling through plank, floor, ceiling or any other interior structure that is solid, bolt plywood to hull with through bolts, "ready rod". You don't want the patch failing totally during transit. Where there is no suitable anchor inside,add one. Round the hull sides of the temporary plank so as not to cut through the rubber. Once in place tighten the nuts untill the rubber has formed a tight seal. While you are at it, attach a skid to the bottom to prevent damage on launch. Splash boat, leave it on the collar all night, if it's still there in the morning you may have 1/2 a chance. If you attempt this, humour me and throw a few empty oil barrels below deck and have someone chase you in another boat. Good luck.
07-03-2008, 11:32 PM
If it is just gaps where the ply patches don't contact the hull and for short term usage, how about the expanding foam in a aerosol can squirted into the gaps? Patches can be well affixed to a wood core hull with drywall or deck screws.
This stuff here is supposedly closed cell or nearly closed cell and possibly waterproof as well. Just a thought.
* 2 Formulas - Fast Rise E-84 Fire-Rated Surface Spray and Slow Rise, Low-Pressure Cavity Fill Formula
* Closed Cell Polyurethane Foam Insulation - Expands 8 to 1 for better control and less waste.
* R-7 Per Inch - Low perm rating makes it practically waterproof
* Easy to use, portable and disposable - Completely self-contained kits. No power supply or additional machinery required!
* Toll-Free Technical Support - 100% guarantee against defect
* Air Seals, insulates, soundproofs, water resistant, 1000's of uses!
07-06-2008, 02:35 PM
what about "torch down" roofing material with wet roof cement? (with plywood over this of course to protect it).
do you think this would be waterproof?
07-07-2008, 06:39 AM
I'm only familiar with the roofing material with granules, which seem inappropriate for you needs, but any sealing material that is a sealant not an adhesive, and that stays relatively flexible, and is cheap, is the approach I would take.
After all, everything you are applying will eventually have to be removed, and, unless you are grinding down to bare wood(plywood), nothing will stick too well anyway. I would suggest to fill all voids with flexible sealant used as a gasket, pumped in as far as possible after the patch is installed and fastened as often and as good as you can without making things worse. Let said sealant dry as long as you can, to resist the water pressure, and have as many pumps as is practicable( gas powered?) as you probably already have thought of.
Bonn Voyage! ( a little gallows humor here).
07-07-2008, 12:46 PM
Yes, roof cement will be waterproof. It's used all the time in a pinch.
07-07-2008, 05:06 PM
it sounds like some thin galvanized steel sheet tacked on with roofing nails would be fine.
And then smear the PL premium into the gaps. And perhaps use some expanding foam sealer on the inside.
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