More issues with our hull!

LAWilliams

Active Member
Well after six months of repairing our cracked deck on CD, we finally completed the deck prep for paint and flipped her over to start on the hull repairs. SURPRISE! I found an area 24" x 18" under the cockpit that is completely detached from the foam. The area flexes from 1/4 " to 1/2" until it hits the old foam. This area starts about 2" from the keel and reaches all the way down to about 1 1/2" from the chine. As we have no access to the area (under the cockpit)
 
Sorry. posted before I finished Has anyone else encountered this? I am guessing we are going to have to drill a series of holes in the hull and inject expanding foam or thickened epoxy to reestablish a bond between the old foam and glass. Several questions. Will Thixo bond to old foam and raw glass? Is it to thick to spread out to cover a large area. Will it just melt the foam? Would an expanding foam bond enough to hold the hull back down to the foam? How many holes would I need to drill to be able to cover the area? We are stuck at this point until we address this issue.
 
Expanding foam is probably your best bet... problem is, nothing sticks that well to cr@ppy old degraded existing foam. Also, the new foam tends to expand in directions which are useless for your purpose... the path of least resistance, so to speak. Just an idea here, be sure to hear from others first before you do any cutting: how about installing an inspection port (or two) where you can access that area under the cockpit, clean out as much loose or degraded existing foam as possible, tape up the gap or otherwise "corral" or contain the new foam in the target area, then let the new foam fill the target area? :confused:

Just an idea, and I've only used expanding foam once or twice in the past, so others may have better solutions. Another thing to consider: you want water to drain out of your hull properly, and unchecked or uncontrolled use of expanding foam can lead to drainage problems. But I did solve a similar problem by using this method, and it stiffened up the cockpit floor with the added support. Also, you wouldn't have to drill a bunch of holes which you would later have to close. My friend "T-Bone" knows more about 2-part expanding foam than I do, he used it all the time to repair surfboards... I'll ask him about this problem when I get a chance. :rolleyes:
 
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I had the same problem with an old hull that was destined to be a hard use "beach banger". I ended up drilling two holes in the bottom of the hull
right over the hollow area and then squirting in about half a can of hardware store exterior Right Stuff foam-in-place foam. Make sure the holes are the same size of the Right Stuff tube. I then repaired the holes with MarineTex. It worked but not my finest boatwright hour. Yeah, I know, Right Stuff is not marine grade and might soak up some water in the bilge - a quick and dirty repair at best.

(Name withheld to protect reputation)
 
I looked at the Amazon selection of expanding foam and none of them claim to be waterproof, just water resistant. Great stuff had one for use in ponds / water features that looked promising. I think any of these foams are going to be subject to water absorption but it beats a loose hull.
 
My friend used Clark foam, if I remember correctly... I'm gonna call him in a few moments and ask him about it. I may be confusing brand names here, as my friend bought some supplies from an industrial warehouse in San Diego. Diversified Materials Company, something like that... resin by the 55-gallon drum, large bottles or cans of MEK, cloth by the roll, the whole nine yards. I'll give him a holler in a bit and see what he says... :cool:

Edit: Left a message for my friend, he may be out paddling right now... he's big on paddleboarding. I'll relay whatever info he gives me when I get it, aye? :rolleyes:
 
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Okay, just got the call, and Tommy is the man... he says to use 2-part foam, which you can order from any good industrial warehouse that deals in that sort of product, it'll be much cheaper than buying it from a boat shop or marine supply store. The foam comes in different densities, he mentioned a range between 1-lb. density and 4-lb. density, but he most commonly used 2-lb. density for surfboards. Higher-density foam would be better for your application, like the 4-lb. density foam. He specifically warned against using that cheap cr@p from the Depot for filling cracks and gaps, that stuff is way too porous and would just be a waste of money... you definitely want good 2-part foam. :rolleyes:

Containment is important too, he said to seal off the area as best you can with tape, as the foam will also cure to a higher density if it is contained in such a manner. He said that if you drill a hole (or holes), you'll want to tape those up as soon as you dump the foam in there, maybe even weight the tape to keep it tight. Same principle with the rest of the tape, maybe back it with something solid so the expanding foam doesn't just push through the tape and go on its merry way. I'm thinking towels weighted with something like metal rods or wooden boards, you'll have to figure out that part. But the better you contain the foam in the target area, the higher the density of the foam itself, and THAT is what you want for support. ;)

Okey-dokey, I think that's about it, if I remember anything else later I'll tack it on here, but this sounds like your best bet for dealing with the situation. If you have no industrial warehouse in your area, and you have trouble finding a decent product online, I think DMC or Diversified Materials Company is still in business, they're in La Mesa (San Diego), maybe they can ship the stuff to ya. I bought some 2-part foam from them in the past, and they're a legit outfit... wouldn't hurt to mention your specific purpose of filling a void between cockpit & hull, as there may have been advances made since I bought the foam, and one product or brand may be more suitable than another. Alright, that's it for now, good luck to ya!!! :D

P.S. Oh, yeah, once you mix this 2-part foam it'll start expanding like crazy, so get it into the void as quickly & efficiently as you can before it gets out of control, lol. I think I used a funnel to dump mine into the void, had everything laid out and ready to go before I ever mixed the foam. Cheers!!! :cool:
 
2-part foam would be the preferred route (you can buy it here) - but getting it installed would be a complete PITA. if you had a porthole in the front wall of the cockpit, and had the boat up tilted with the bow end up, you could maybe reach in the hole, pour it and let gravity drip it down in between the hull and cockpit floor. but if you tilt it too high, it could flow right past the cockpit... and if you tilt it too low, the flow might stay at the forward end of the cockpit and not make it far enough back.

honestly, I'd probably just use the same method as Alan mentioned above - drill tiny holes, and use the expanding foam from a can that you can just squirt/spray using the provided nozzles. if you can find the pond version great, if not... meh, I probably wouldn't sweat it that much.
 
And THAT is the choice the OP has to make: go to the trouble & expense of using 2-part foam, or opt for the cheaper route and bring on the cr@p shoot, which may or may not solve the problem. Meh, maybe he'll luck out... :rolleyes:
 
Thanks for all the feedback. I agree the 2 part foam would be the best product, however after burning thru a ton of it resetting all the blocks I am like Tag , I don't know of a good way to get where we need it . There is no access to that part of the hull due to the starboard foam block (that we just reset and the idea of cutting access thru the cockpit is not appealing. If we could figure out a way to inject the 2 part foam thru a series of holes that would do it. I just don't know a method that would allow you to mix the foam , move to a syringe or cartridge to inject it before it goes off.
 
True... you don't have much time once the 2-part foam is mixed, which is why it's so critical to get it where it ya need it before it starts growing like 'THE BLOB.' :eek:

How about using slightly larger holes & a funnel? And moving quickly from hole to hole, lol... ;)
 
When I used the 2-part foam, I mixed it in a pitcher and then poured it through a funnel (while the mixture was still liquid). :confused:

Had the boat already positioned as best I could, so the mixed foam settled where I needed it. Cutting into the hull and making the target area more specific would've helped, particularly through containment. :rolleyes:

But if you cut or drill your holes just large enough to see through, you could better position or adjust the hull so the foam is where ya need it most... hope for the best, and close the holes afterward, even if you gotta fair 'em out a bit and re-glass them. ;)

Again, just my $.02, and suggestions which may or may not help ya... at least you're generating some input, better than no suggestions at all, lol. :cool:
 
I agree with CC that the 2-part foam is better. However, Great Stuff is sticky stuff and people have successfully used it to glue the blocks down, so it "should" work for this job. I would try the outdoor version. Keep in mind, water absorbency should not be a big issue if your boat does not leak! And if it does spring a leak and you dry it quickly, you should again be OK.
 
Thanks again guys for the feedback. We took another look inside the hull / cockpit junction and my son found an opening right where we needed it. We already had an inspection port on the cockpit wall. We ordered the US Composites 4lb. foam and should get it in a few days. I think Tag's method should work if we can get the foam running toward the transom before it starts to set up. We will strap the area prior to the pour and hopefully avoid the "bulge". We will let you know how it went in a few days. Doing it right is better than doing it over. My fathers mantra! I agree.
 
Beldar beat me too it. Great Stuff will work, just make sure the boat doesn't leak or water is left inside. 8 small blobs ought to do ya, and that will leave plenty of area for water to drain. The last thing I would do is fill the entire space below the cockpit with foam and block water/air flow.
 
I had the same problem with an old hull that was destined to be a hard use "beach banger". I ended up drilling two holes in the bottom of the hull
right over the hollow area and then squirting in about half a can of hardware store exterior Right Stuff foam-in-place foam. Make sure the holes are the same size of the Right Stuff tube. I then repaired the holes with MarineTex. It worked but not my finest boatwright hour. Yeah, I know, Right Stuff is not marine grade and might soak up some water in the bilge - a quick and dirty repair at best.(Name withheld to protect reputation)
In your "dispatching" of many Sunfish relics, haven't you found the empty space between the cockpit and hull is "factory", designed-in, and always present?
 
The only one that I disposed of was cut on both sides of the cockpit, so I really didn't get a good idea of the transition past the cockpit. Live and learn!
\
 
The many Sunfish hulls we have worked on have 8-10 blobs of two part expanding foam/adhesive between the cockpit and hull. Many times there is gelcoat stress cracking (spider cracks) right over where the blobs are. Overall though there is a space and if any water gets in it should flow freely through that space. So we don't have an issue with adding a few new blobs of Great Stuff by drilling small access holes through the cockpit and/or putting a few small squirts in through a deck plate forward of the daggerboard trunk.
 
I've had other boats with a hull flexing issue (Puffer, for instance) and I just cut a hole in the bottom and glass a support "rib" to the pan (or cockpit sole) or whatever was needed. Then glass the boat bottom back up. I did this only because a fairly large area was flexing too much for my liking. Totally took out any flexing and there were enough contact/rib areas, to spread the load out over a larger area. I agree...on a Sunfish...a couple "blobs" of Great Stuff, shot in thru some tiny holes, spaced apart...maybe 6-10inches or so...will stiffen things up quite a bit. Then keep it from leaking or drain it as needed right afterwards.
 
One of my keel repairs found a thin layer of Styrofoam between the outermost surface and the interior bottom of the cockpit tub—normally out of sight. The sun has cast a shadow on the thin Styrofoam strip, which appears as a beige color in the photograph:

P6150001.JPG
 
That is very interesting, I have never seen another photo of a keel repair where Stryrofoam appeared in the void. Do you think this was a factory install or just some sloppy building? I have never understood why the SF has this void in the layup of the fiberglass on such a high impact area.
 
Seems like they attempted in design to make it lite by forming the shape of a keel rather than flat or to add weight by filling it with wood or something else. Sort if like the principle of creating strength through the shape of your construction materials. Or like welding something out of thinner gauge angle iron instead of heavier gauge flat iron. The shape of the keel gives it whatever strength it needs while reducing weight. Thats all a lot swirling in my head...I actually have no clue...but the voids suck anyway anyway.
 
Sorry. posted before I finished Has anyone else encountered this? I am guessing we are going to have to drill a series of holes in the hull and inject expanding foam or thickened epoxy to reestablish a bond between the old foam and glass. Several questions. Will Thixo bond to old foam and raw glass? Is it to thick to spread out to cover a large area. Will it just melt the foam? Would an expanding foam bond enough to hold the hull back down to the foam? How many holes would I need to drill to be able to cover the area? We are stuck at this point until we address this issue.
If you've already started, may I suggest a turkey baster? ($1 at Dollar Tree). Also handy for refreshing brake fluid in the car's brake fluid reservoir. :cool:

I've got three Sunfish in the yard right now. I'll check for the 1/2-inch flex you've discovered--later today.

The bottom flexes amply elsewhere, and this may be "normal". :confused:
 
We are on hold with the repair as we are waiting on our 2 part 4lb. foam to come in from US Composites. Since my son hold the gap between the cockpit and hull we are going to try to pour the foam in the gap and move the boat to a slight stern down position for a minute and then move it to a level position slightly toward the chine. The timing is going to be critical on placing the foam in the right place before it sets up. If this works we should have a solid repair. I like the turkey baster idea. Thanks for the feedback.
 
I've checked my three Sunfish, which happened to be stored deck-down, and resulted in the same findings.

While there is some flexing (flexion?) between the cockpit and the hull bottom, it took an ample push—using my thumb and index-knuckle. The rest of the hull flexed somewhat less.

Keep in mind that "a little goes a long way", and over filled, can actually cause damage. :eek: One "turkey-baster-full" will probably do the whole area.
 
I've checked my three Sunfish, which happened to be stored deck-down, and resulted in the same findings.

While there is some flexing (flexion?) between the cockpit and the hull bottom, it took an ample push—using my thumb and index-knuckle. The rest of the hull flexed somewhat less.

Keep in mind that "a little goes a long way", and over filled, can actually cause damage. :eek: One "turkey-baster-full" will probably do the whole area.
L & VW, I found it odd that this flex is only on starboard side of the cockpit, the port side is solid. I agree with the little goes a long way , we encountered this several times resetting all our forward blocks. It will be a challenge but I think our plan will work. Will advise when completed. Thanks
 
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