Spray or pour polyurethane foam

[tboydva]

I've been searching these forums as I prepare to foam in under my new boat floor (old boat - new floor!). These appear to be the most relevant threads:

http://forums.iboats.com/showthread.php?p=1690275
http://forums.iboats.com/archive/index.php/t-224373.html

Seems like it's worthwhile using, but I have an experience question for those who may have put in polyurethane foams. I'm trying to decide if I should go with expanding "pour" foams or a spay in type. Here's what I see as the option(s):

Expanding pour

Spray or what I'm leaning toward

Does anyone have any experience with these different forms? Any recommendations? I was planning to put in two panels, spray or pour underneath (fully), then put the last panel in and pour or spray through larger holes in the deck...

Thanks in advance for advise!

 

[salty87]

Re: Spray or pour polyurethane foam

the spray stuff looks interesting though i didn't see the price.

i'd be tempted, depending on cost, to go with the spray and shoot it up under the gunnels instead of the deck. otherwise, i don't see an advantage to the spray.

 

[Coors]

Re: Spray or pour polyurethane foam

Yep, under the gunnells is only place it will even help, unless you want rot under the deck.

 

[tboydva]

Re: Spray or pour polyurethane foam

Thanks for the answers! I'm not sure what you mean about rot under the deck? I removed all the old foam and it seemed like it was OK (just not put in very well). Am I to assume you're talking about waterlogging? I'm putting in a "drain" and I won't ANY wood on this boat at all. The foam won't rot I don't imagine will it?

Thanks,

Tom

 

[Coors]

Re: Spray or pour polyurethane foam

what will the deck be made off?
No, the foam won't rot, just waterlog, about 600 lbs worth.

 

[oops!]

Re: Spray or pour polyurethane foam

foam rots boats....if you can make sure the hull is strong enough.....(sometimes foam is structural).....(approx 10%)

it is a better idea to add the foam under the gunwhales ot under the top cap.....

read boat rot....wet foam prevention....it is a super thread

 

[cprince]

Re: Spray or pour polyurethane foam

Yep, under the gunnells is only place it will even help, unless you want rot under the deck.

Hopefully this is not considered hijacking a thread attempt, but...

I was considering my foam options with my little project. When i removed the casting deck there was Styrofoam in the bulkhead/casting deck. Should I not replace it then? I am planing on sealing it. Are you saying that even if it is sealed, condensation will still cause damage?

Or...

Am I comparing apples to oranges? Foam under a floor/ Styrofoam under a casting deck.

I have been reading this forum every night, digging through as many posts as possible trying to educate myself with the experience's of others. There are, perhaps, still some key concepts that I likely don't understand.

The gunwale on my boat is not composed in a sandwich type thing that would be able to take any foam. Would this then mean I should not use foam any where on my boat?

(If you click on my blog link in my sig, you will see my setup.)

Thanks in advance!

 

[oops!]

Re: Spray or pour polyurethane foam

YOU HIJACKER !

kidding



ok.....thats it.... im bumping boat rot again......

any foam in a boat will eventually take on water and water logg.....that means rot......no way around it......a lot of us leave it out or use other methods

 

[Coors]

Re: Spray or pour polyurethane foam

Read Oops ping pong ball theory.

 

[Coors]

Re: Spray or pour polyurethane foam

Looking at the pics of your boat-go with Bondo's soda bottles, you have room.

 

[salty87]

Re: Spray or pour polyurethane foam

cprince...i think you're comparing apples to oranges, or maybe just different kinds of apples. you should be able to design some sort of drainage for it. as you observed in your post, water will find a way in so leave a way for it to get out. you can also design a better way to install the seat up there without leaving the hole. how about a plate mounted under the deck with post extending up through the deck and properly sealed?

 

[cprince]

Re: Spray or pour polyurethane foam

In an effort to curb my hijacking tendencies, I have replied to everyone in my boat project thread; Here


Sorry tboydva!

 

[tboydva]

Re: Spray or pour polyurethane foam

No worries about the hijack! I'm trying to get all the info I can get. Perhaps I should elaborate too. Eventually, when done, I'm going to post pictures of my saga. However, here's progress to date and my plan (open for criticism). My boat is aluminum and I've been on a wood eradication program since starting to replace the floor. I have put additional aluminum runners in to provide more support for the floor (actually my buddy who can weld aluminum like no one's business did the work). My same friend cut me 5/32 aluminum sheeting to rivet in as a new floor. I wanted to inject foam to a) deaden sound, and b) really firm up the floor. I did notice a little water logging in the foam I removed. I'll try to attach a picture of the new floor support.

As for future waterlogging, I'm going to do something similar to a french drain system. I've got a PVC pipe with holes in it and cut lengthwise so it's like a half circle. I'm going to load it with old bread compressed as well as possible, then foam in over it. Water, ants, etc will remove the bread over time, leaving a means for water to escape (got this tip from my brother-in-law).

I am leaning towards the spray in foam (system 15). It's expensive, but the sales guys say it does a very good job sealing out water.

Also, you might see the transom removed in the picture - I've got some very nice fiberglass "plywood" which I'm cutting to replace it. Other than the strips of teak, there'll be no wood on this boat!

 

[redfury]

Re: Spray or pour polyurethane foam

You could always leave yourself a hose up at the front of the boat that you could spray water into your "french" hose system to blow out the bread too. You might find that you don't take on enough water to get that bread out of there. It works great for soldering water lines, but that has pressure behind it. I'd seriously consider giving yourself that option.

Going all aluminum though is a great way to save yourself future headaches.
There's a boat builder up here called 'Lake Assault' that builds their entire boat out of metal, diamond plate floors. Pricey, but you get a boat that will last you forever and should never have to do any repairs to the hull.

 

[salty87]

Re: Spray or pour polyurethane foam

i'd try to spray the underside of the deck and not have any foam on the hull...skip the pvc. run some 2x4's or whatever that you can pull off after foaming so it fits right onto the stringer system.

 

[tboydva]

Re: Spray or pour polyurethane foam

Gents,

Was fishing (canoe float) over the past two days. Great ideas - I actually planned to leave the bow section for last and do as you say (hose out the bread). I would like to have the foam fill in from hull to floor to stiffen it since it's an aluminum sheet. Even though it's a bit pricey, I think I'm gonna go with the System15 spray in system. It's in my restoration budget allocation. Until I can afford one of these, I'm going to have to make this one just like I want it. Hope to be posting the full suite of pictures in the "completed project" forum some day reasonably soon! Thanks again for all the suggestions.

Tom