More Flotation Foam Questions.

[SwampThing]

Well live and learn, apparently I didn't do a good enough job of checking the foam out entirely when I laid my new floor in and now it ALL has to come out.

So my questions are this:

I have an 1986 20ft Bayliner Capri Cuddy. I've read a lot of the threads on foam around here and all the stuff people use to replace it with. Including pop bottles and packing peanuts. The factory obviously used some type of expandable foam that fills every nook and cranny. How much structural support / integrity is the foam responsible for? Or is it only for flotation purposes.

I'm thinking as the (factory installed) foam expands it has to be creating some force on the hull and thus helping to keep the integrity of the shape of the hull? no?

What I'm worried about is that if I dig it all out and don't replace it, or use the wrong thing to replace it with, will I create a condition that allows the hull to flex or flex to the point of spider webbing and or cracking the fiberglass?

Okay so If I do replace it, what are the best options to use and where do I get the stuff at a reasonable price? Best case, yea I'd like to use an expandable foam and replace it with close to what was originally there. Being a noob at this stuff, I kind of need to be clued in on this one. Can anyone help on this one?

I fully redid the interior and then discovered that the foam needs replacing. I'm currently in the process of removing the foam but making access holes in inconspicuous areas of the floor that I'm going to have to repair when finished. So far all of the wood where I've drilled with a 4 in hole saw has been nice clean wood. So I think I lucked out there. There's no mold smell and what actual water I'm getting out is clear in color as well with no mold smell. Great. It's just a real pain to have to remove the foam in this manner.

 

[tmh]

Re: More Flotation Foam Questions.

I used soda bottles for mine, no issues in stability/structure that I see. HOWEVER, my brother has a 1987 Bayliner like yours and we re-did his floor andfound the foam far more packed in and far less stringer support than my boat has. The foam looked to definately be a part of the support structure on his Bayliner. I don't know what he's putting in there (I was only in on the tear out) but I think it needs to be some sort of expanding foam or he'll have to add stringer supports some how.

 

[sdunt]

Re: More Flotation Foam Questions.

personally not a fan of expanding foam. Fortunately my Antique didn't have any to start with ..

US composites is a good source for 2 part foam: http://www.uscomposites.com/foam.html

 

[SwampThing]

Re: More Flotation Foam Questions.

Thanks for the info sdubt. I think that's the way I'm going to go. Curious as to why you don't care for expanding foam though.

Also I'm of the opinion that Bayliner was using the foam as extra flotation for the added weight of the 125 force outboard. I discovered that the foam only runs about 2/3's the length of the stringer up from the transom area.
Doesn't appear to have anything to do with the structural integrity of the hull in the sense that I was referring to.

Also funny that only the back half of it was wet, but the lean and resulting steering instability was phenomenal. The only thing I can figure at this piont is that yes, when that foam is saturated it's weight increases by a factor of more than 10.

tmh, If it works for you then that's okay I guess, but I would never consider using soda bottles as an alternative. I'd go with shipping peanuts before that, or dead air. At the cost of the foam sdunt sent the link for, you could have purchased it by returning all those pop bottles.

Thanks again guys for the responses.

I'm still removing the old foam. But I'll do a follow up when I make some more progress for the benefit of anyone that may stumble on this thread in the future.

 

[sdunt]

Re: More Flotation Foam Questions.

I'm of the mind that 97% or 98% closed cell means that 2 or 3% of that foam is going to soak up water.

In my case I used house building foam: http://www.shareaproject.com/pages/imageDetail,p,148,i,2768,00.html

because in personal use of that product, it does not soak up water. Keep in mind the foam you are taking out is 'closed cell foam' so how did it get wet?? If that foam failed, will the new stuff you put in its place fail as well? When will it start to take on water?

US composites cautions that if you leave the foam in contact with water long enough it will degrade. How do you ensure that it stays dry? What boat is perfectly dry?

Also the testing this gentleman did with various types of foams also lead me to use building foam: http://www.shortypen.com/boats/oday19/float/index.htm

Plus, building foam is approximately $20 a sheet and that is 5 1/3 Cubic foot of foam, or about $4 a cubic foot. Pour in place foams are $7 per cubic ft. IF ... IF you get 100% expansion of it..

I had to install the building foam in strips, so it is not conformed or adhered to the hull, there are gaps or channels running front to back so I can tip the nose of the boat up and know that if there is water under the floor, it will be draining out to the bilge.. http://www.shareaproject.com/pages/imageDetail,p,148,i,2797,00.html