to foam or not to foam

[bob johnson]

That is a good idea for YOUR boat. Bu not all boats are built that way. So that is why each person have to evaluate which way they want to go when thinking about foaming or not foaming. A lot of folks have contemplated this exact situation and I believe many of them still wonder if they chose the best option for their rebuild.
Like I previously stated, there is no right way or wrong way. Only what the owner ways to do. JMHO

yeah I am not proposing how anyone should do it....just want to say that that 2 parts foam sucks..... unless there is a formula that does NOT absorb water

 

[Cutlass18]

I'll post some pictures when I get the floor out. I'm debating ripping some PVC in half and epoxying it in to improve drainage.

 

[mickyryan]

well here is the thing if the water has someplace to go then it will dry out, that was my point , and bob I see your point, so when foaming think of making sure there is evac points for the water and air movement I would guess and I don't care what they say about closed cell open cell my foam that was locked in was holding water it never went through a freeze thaw cycle the **** just eventually seams to hold water if it has nowhere to go I guess lol

 

[mickyryan]

at this time I would like to point out that it appears bob is hoarding tins by his pic I see a second project behind the first in aforementioned pic ... admit it admit it bob /beams bright flashlight down on bob!

 

[GA_Boater]

The problem is that when expanding foam is put below the deck, it expands and fills every nook and cranny, no matter is the boat is tin, glass or wood. If Bob had used expanding foam, all the nice water drains would be plugged. Using the sheet foam fixed the water path problem.

A word of caution - Sheet foam isn't the right choice for most fiberglass boats.

 

[jbcurt00]

at this time I would like to point out that it appears bob is hoarding tins by his pic I see a second project behind the first in aforementioned pic ..!

Uh, yeah, tip of the iceberg.....

Theres a few boats in his boat yard, mine too...

 

[sphelps]

A word of caution - Sheet foam isn't the right choice for most fiberglass boats.

GA, any reason why not ? Only reason I can think is on some f/g boats pour in foam may be structural ..

 

[Woodonglass]

Yeah, I'm wondering the same thing. If it's cut to fit and fit tightly it's fine. I will admit that the pour in foam will add a bit more structural support since it adheres to everything it touches. However, unless the hull is specifically designed to require the foam for Hull Strength, then it's not a major concern. Some boats in the 80's and 90's WERE foamed hulls and depended on it for their structural integrity. But...most of them had NO stringers or bulkheads and had much thinner hull walls as well. DeepBlue says that the 2# pour in foam, from his testing,seems to have a bit more compression strength, but again, if the hull wasn't designed needing this support, then the point is moot. If all you're looking for is Flotation, then the slab foam will get the job done, no matter what the boat is made from. That's this Old Dumb Okies opinion based on my research and experience.

 

[Woodonglass]

yeah I am not proposing how anyone should do it....just want to say that that 2 parts foam sucks..... unless there is a formula that does NOT absorb water

The NEW 2 part foam, is much more water resistant than what was put into boats 20 years ago. It is 100% closed cell and won't absorb water unless it's exposed to to for Many Many Years. With proper maintenance and Care it shouldn't be a problem.

 

[GA_Boater]

GA, any reason why not ? Only reason I can think is on some f/g boats pour in foam may be structural ..

Yes, structural support is why I said "most". There is thin glass and thick glass, stringer-less, short stringers - many construction methods where expanding foam is needed and foam sheets just don't meet the structural requirement.

Expanding 2 part foam and sheet insulation can help save a life, expanded foam can help save the boat. It's all in how the boat is built.

 

[DeepBlue2010]

It is not just the structural aspects. Two parts Urethane foam - if sold by reputable company - has been test according to the Coast Guard Regulation # 33 CFR 183.114. This means that this specific foam has been tested for so many aspects that relates to marine and boat use.

For example, Extruded Polystyrene Foam (XPS) (a.k.a blue board or pink board) is not tested for fuel or solvents resistance. While the two parts marine foam is tested for fuel and solvent resistance; even Acetone doesn't impact it.

Also, the the XPS board in home improvement stores are not designed to provide flotation and there is nothing in the datasheets about their buoyancy at all. Of course the buoyancy can be tested and determined but the product was designed for it to begin with. It was just designed to stay still between studs and provide insulation proportion to its R-Value.

Dow makes a specific product for flotation called Styrofoam Buoyancy Billets with a stated buoyancy of 55 Ib/sf under ideal conditions but with more practical agreed upon value of 48Ib/sf. 2 parts Polyurethane expandable foam is tested at 60Ib/sf

At the end of the day, my goal is not to promote a product and debunk the other. The debated point I responded to before was that the two products are equivalents.

My point is they are not and this is not necessarily a bad thing. As long as the boat owner is well informed about the advantages and disadvantages of each product, he/she will be able to make the right decisions on how to deploy them into the design based on their characteristics and the situation needs.
The right decision still could be using the blue board (maybe to compensate for another design goal, provide drain channels for instance) and work around the disadvantages somehow (like beefing up the hull a little with an extra layer of 1708 if needed or using a two parts expandable foam where is no draining issues to worry about)

 

[444]

Foam was removed from my boat during the resto. Whether you add it it in or not, don't expect it to affect how it handles on the water. I'm sure you're aware of foam waterlogging.