TO FOAM OR NOT TO FOAM????? That is the question

[kcassells]

Thanks! Good info for all.

 

[mickyryan]

Scott, that's got to be the best explanation i have read, it is hard to explain to folks but believe me 2 part foam is the best foam to use on a boat period. if it had foam put it back plain and simple.

 

[Davetowz]

My last build, I did the stack the foam board thing. I regret it every time I am on the water and have the low pitch noise from the engine droning out every chance of a less than yelling conversation. If it takes a grand in pour foam, my current build will be 100% filled, not just for safety, but also for sanity.I researched, and did before my last build, all kind of answers, why not to use pour foam, never did hear from those who didn't afterwards, all kind of cheap guys explaining why they where cutting corners. I was trying to do the job " on the cheap" I did and regret it. Just foam the below decks areas, ensure encapsulation of the areas to prevent water ingress or allow for drainage and ventilation to dry. Last comment, use the appropriate 2lb pour foams, not the crap in a can from the home despot or the big blue box store, not even in the same universe as a material.

 

[Scott Danforth]

Scott, that's got to be the best explanation i have read, it is hard to explain to folks but believe me 2 part foam is the best foam to use on a boat period. if it had foam put it back plain and simple.

Micky, its mechanically what happens. once people understand why something happens, you can see how to prevent it.

BTW, some bayliners with thin fiberglass hulls use 4# foam because it is more structural than the 2#. I have used 16# foam for filling some cavities at work. the navy uses some that is closer to 20# on submarines

 

[mickyryan]

any ideas of the weight difference on the different pound foams ? i know i have always used 4 lb density on any rehabs i have done but really because that was what was readily available and what these forums recommended.
after working on this boston wailer i see no reason not to trust foam for structure since basically that's what they did , the glass was just a covering , i imagine in a few years we might see boats from plastic that are just as strong with foam filled core.

 

[jdvasher]

My last build, I did the stack the foam board thing. I regret it every time I am on the water and have the low pitch noise from the engine droning out every chance of a less than yelling conversation. If it takes a grand in pour foam, my current build will be 100% filled, not just for safety, but also for sanity.I researched, and did before my last build, all kind of answers, why not to use pour foam, never did hear from those who didn't afterwards, all kind of cheap guys explaining why they where cutting corners. I was trying to do the job " on the cheap" I did and regret it. Just foam the below decks areas, ensure encapsulation of the areas to prevent water ingress or allow for drainage and ventilation to dry. Last comment, use the appropriate 2lb pour foams, not the crap in a can from the home despot or the big blue box store, not even in the same universe as a material.

I'm definitely not cutting any corners on this project, my final decision will be made on what I feel is best, not the cost. I hear many that say if you encapsulate the foam then it will last forever. problem is, if you encapsulate the foam then that means it is no longer bonded to the boat and in that case I don't see the difference from foam sheet. If it is poured in place it would bond to the boat and I totally agree, would add to the structure and sound deadening. The problem I see with that is there are going to be rivets that develop leaks over time and when they do, there will be no where for the water to go. with the foam sheets any water that makes its way in will drain to the back as was intended. Also if the foam is bonded to the boat there will be no way of knowing weather there is a leak or not in the first place. the boat will just keep getting heavier and heavier, which really goes against my whole plan for the boat. I am eliminating almost all of the wood on the boat. It will have a composite floor and the whole hull has been reinforced with aluminum bracing to account for that. The only wood that will still exist is the mahogany and the Marine grade transom that has been very well sealed. hopefully this boat will last another 50 years, will see, but I know the expanding foam wont last that long without soaking up water.

 

[Scott Danforth]

any ideas of the weight difference on the different pound foams ?

2# foam is 2LB/cubic foot (pure flotation)
4# foam is 4LB/cubic foot (light structural foam)
8# foam is 8#/cubic foot (medium structural foam)
16# foam is 16#/cubic foot (you cant dent it with a hammer)
20# foam is 20#/cubic foot (it doesnt crush as 10,000 feet below like us puny humans do)
water is 64#/cubic foot

 

[mickyryan]

I ALWAYS WONDERED OF THE LB REFERRED TO ACTUAL FOAM OR 2PSI , NEVER RESEARCHED ENOUGH TO FIGURE IT OUT ugg ffing caps lock loil

 

[GA_Boater]

Expanded 2lb foam weighs about 2lb per CF and so on.

 

[awallace]

I have decided to foam it, I will go with foam sheets laminated together instead of expanding foam though. Throughout the entire restoration, one main goal has been on my mind and has played a major part in my decisions. This is an old boat, with rivets, There is a good chance that it will need repairs at some point. I have laid out the floor for removable panels for this reason so I just cannot see filling will expanding foam. I am not sure how to add this info to my signature yet but if anyone is interested, here is a link to the resto.. https://forums.iboats.com/forum/boat...ay-restoration

For your consideration, if you have poured foam in your hull and for some reason you punch a hole in the hull, the expanded foam will significantly reduce the speed of the water that is entering the hull. In the case of foam board unless it is sandwiched in the hull tight enough to make a water tight seal (unlikely), the flow will be unrestricted. The argument you made regarding potential future repairs to rivets is valid however a little inconvenience (in my case) is being offset with a little "peace of mind".
Some of the places I go fishing, No cell coverage and no one else for perhaps a week or more, so piece of mind is important to me. Your situation might be easier to justify.
cheers