Need some help with foam installation.

[Mark42]

The foam that was in my Niagara's gunnels and under deck is missing. Replacing this is one project I put off during the resto of this little boat. <br /><br />The problem I have is that turning the boat upside down to pour foam into these areas is not an option for me.<br /><br />Thought of these solutions:<br /><br />- Use the expanding spray home insulating foam for under the gunnels because it's sticky and will stay there. Gunnels are about 7" wide and 5" high.<br /><br />- Fill large plastic bag full of regular marine foam and support (w/plywood or corragated cardboard) in place under front deck until it hardens. Remove plastic bag and glue hardened foam to underside of deck. <br /> <br />- Buy the rigid home insulation and cut to fit under deck. Glue in place.<br /><br />One problem I have is that the thickness of the original under deck foam is unknown. So I will have to guess at how thick to make it. But I guess it was not as thick as the dashboard is high - about 6-7".<br /><br />My goal is to make sure this boat floats at at least at water level so we have something to hang onto/sit in during an emergency. The boat/motor & trailer weighed in at 1200LBS at a truck scale. <br /><br />Any other ideas for foaming this boat upright?<br /><br />Thanks,<br /><br />Mark.

 

[Eggkr8]

Re: Need some help with foam installation.

Hi Mark,<br /><br />I doubt that the vintage boats that we got ever came with any foam. Mine has none in the gunwales nor sub floor (yet). On my boat all of my control cables and wires pass through my gunwales and would be concerned about accessibility for maintenance. Maybe if you re-routed everything through a PVC conduit and then foamed? If you do foam the gunwales, why not just wedge a board (maybe use something like Saran wrap on the side in contact with the foam for releasing) against the open bottom and go to town?<br /><br />As for the floor, why not the drill and pour technique? <br /><br />If you haven't checked out the 'plastic bottles and other stupid ideas' go ahead and do so, there is a lot of discussing there about why and where to use marine foam and some cost saving options<br /><br />Cheers<br />e

 

[Mark42]

Re: Need some help with foam installation.

Hi Eggkr8,<br /><br />I have been reading about plastic bottles and other stupid ideas with great amusement. Decided that bottles and ping-pong balls are not for me. <br /><br />This boat did come foamed. The under floor foam is in place and OK. I can see the remains of some foam under the gunnels and deck. I guess age (and prior owners) took its toll on the remaining foam. When I put in new wire harness and steering cable they run just under the gunnel, not inside. I did that so cardboard or something could be used to block off the bottom of the gunnel so the spray foam would not drip down all over the place. Because the steering and wires are underneath, you can't see them without bending over.<br /><br />I just thought that I could do the gunnels with marine foam by filling trash can bags only half full of foam and then stuff into the gunnels with the cardboard tapped to the bottom until they harden. Figgure a trash can bag only half full and no air should form-fit to the gunnels pretty easy.

 

[JasonJ]

Re: Need some help with foam installation.

Since there will be no continuous exposure to water, and there will be plenty of airflow, I see no reason why you can't use the home stuff in this application. I only frown on home stuff under the floor because there is no air flow and not that great of drainage, so water can just sit and fester. I say use the home stuff for under the gunnels and such. Also remember, it is not dry land weight that you are trying to float. A boat, once submerged, weighs a significant amount less than it does on land. You boat, at around 900-1000 lbs (rough estimate) could weigh as little as 600 lbs once submerged. It is that weight that you are wanting to displace with foam, because the physical structure of boat, motor, etc all displaces water. About 10 cubic feet of foam is all that is needed to keep the boat at the surface. If you have that much room under the floor, you can foam that space and be done with it. If the under floor voids do not yeild enough cubic footage, then you have to look elswhere.

 

[Maximerc]

Re: Need some help with foam installation.

how about cutting a piece of say 2 inch foam board to fit up under the deck area then poke holes thru it to spray foam insulation in between. the foam would not get saturated with water so that should not be a problem. and the 2 inch foam would give a nice flat finsh rather than having blobs of foam hanging.

 

[Chinewalker]

Re: Need some help with foam installation.

I'm with Jason on this one. The foam in a can is fine for above the water-line application where it is unlikely to come into anything more than incidental contact with water and isn't asked to perform structural duties. In the unlikely event that your boat did become swamped it would certainly aid in keeping the boat afloat, at least as well as any original foam was meant to.<br /><br />Good luck!<br />- Scott

 

[18rabbit]

Re: Need some help with foam installation.

Originally posted by Mark42:<br />My goal is to make sure this boat floats at at least at water level so we have something to hang onto/sit in during an emergency. The boat/motor & trailer weighed in at 1200LBS at a truck scale.

That’s the idea behind the requiring of flotation for small boats. They can be partially (mostly!) submerged.<br /><br />This is what I would do: get an approximate weight for the trailer and subtract it from the overall tow weight you already have. Then estimate the volume of all areas on the boat you will be filling with foam. Do the math … 1 sq ft of foam is about 60 lbs of floatation…are you even close to the weight of the boat & motor? If not, pass on this project.

 

[lawyertob]

Re: Need some help with foam installation.

Mark,<br /><br />I hope you know the can of worms you have opened with this thread. <br /><br />From what I have read, the household foam doesn't cure well in large voids...and they consider anything over 1/2 inch a large void...unless you put it in in thin layers and let each layer cure. This type of foam uses moisture from the atmosphere to cure, so it is specifically not for use in enclosed spaces, which kills Maxi's idea.<br /><br />I do like the smooth surface idea from Maxi though. I would use some of the sheet insulation they put on the outside of houses under the brick. It is about 1/2 inch thick and usually has a foil layer on the outside. The insides is made of something similar to marine foam I think. Anyway, cut that stuff to shape to fit snuggly, then tape over the joint after you put it in. You really don't want any leaks.<br /><br />After you get it all formed up, you can mix the marine foam in small containers and put them inside through small sections you left loose. You might even use the "tilt up the bow and drop them in and let them rise to the top method". Not sure who did it, but it was back during the magic rope thread that it was being discussed.<br /><br />Just my $0.02 worth,<br />Joe

 

[Mark42]

Re: Need some help with foam installation.

I'm going to have to grab the tape measure and calculate how much space is in the boat for foaming. It will need about 10 cu/ft, minus what is in the floor now.<br /><br />The floor is solid fiberglass and sealed, underneath is a molded corrigated stringer that is alternatly foam/bilge space. The actual cu/ft of foam is unkown. I can't do anything below the floor without cutting into perfectly good glass. The only space I have available is under the seats, under the deck and under the gunnels. <br /><br />So like 18rabbit said, if I can't come up with the space, it may not be worth it at all.

 

[BillP]

Re: Need some help with foam installation.

I posted this a long time ago but will say again. Measure the foam carefully for pouring. It doesn't always rise evenly, in one direction or squeeze out holes. It can have localized expansion and raise or bust the floor, etc.. <br /><br />I was helping a friend put a new floor in a Donzi Sweet 16 clone back in the late 1960s. We set new stringers with a new tank between them and decided to foam the tank in before glassing the new ply floor down. We poured the foam and set the floor on top thinking it would level the foam and make things easier. Instead it lifted the floor like a muffin with three adults standing on it. The foam didn't even know we were standing on top and raised a foot higher than needed. Had the floor been glassed down something would have busted. The guy who measured the volume was a hot shot mechanical engineer at the Canaveral Space Center so I figured he knew how to calculate this stuff...but I was wrong. We spent the next day chopping foam out!

 

[a_bullfrog_a]

Re: Need some help with foam installation.

I liked the idea of the FOAM POOL NOODLES from the bottles and other bad idea discussion.<br />They are about 5 feet long and 2 should fill that <br />space nicely widthwise. My kids have had the same ones for 3 years now and they are dry as could be<br />after left in the pool all summer. havn't tested <br />them to chemicals myself but being where your <br />putting them it would take quite a spill to get to them.

 

[jimmythekid]

Re: Need some help with foam installation.

oh nooooo