need help with foam problem

hi i have a 1988 starcraft 18ft aluminum v bottom. i am replacing the floor and found foam was a little wet. it is only wet on the bottom but is still a little heavy. just wondering if there is an alternative to expanding foam since it is so expensive, like maybe styrofoam board with moisture resistance? or is the foam act as a structural part of the boat? the foam only runs down the sides of the boat, the middle section is all open for the gas tank and ski storage so i wouldnt need much i dont think. if i decide to do the foam would the 2lb foam work?

Re: need help with foam problem

I hear 2lb foam works fine. I just poured some in my boat, it aint pretty but it fills the nooks that the old foam sticks did not. I am hoping to get a smoother ride from this stuff. It was only $70 for 8cf on the internet.

Re: need help with foam problem

yep 2 lbs will work great !! US composites .com is the best place I have found , and I not sure on a aluminum you can add to much structure but i guess it would add some wouldnt it !! do you get condensation on the sides ?? John

Re: need help with foam problem

ditto

Re: need help with foam problem

Some folks here have use the pool noodles for flotation. Here is a link to a thread that has some info on this. I've seen the noodles for sale for less than $1 each. If I were to do an aluminum boat again I think I would go this route. When I did my aluminum Starcraft, I didn't think about it and just used the pink construction foam from the lumber yard.

Re: need help with foam problem

ya i thought about using the construction foam...how did that work?? im trying to get this boat on the water before the cold hits and dont really want to be in a huge hurry but if it works i may as well use something i can get right away. just worried about safety for the family. is ther any truth to having the injected foam helping to absorb waves and adding strenth to the hull??

Re: need help with foam problem

For you 18' Starcraft, the hull isn't going to need any additional strength from the foam. The construction foam worked OK, but I do see some pink in the bilge area from time to time telling me that the foam is probably working or rubbing on something and wearing some of it away. It was easy enough to put in and I just cut it with my tool box size cross cut hand saw. As I said though, I would go with the noodles if I had to do it again.

Re: need help with foam problem

Oh Great, After I spent 150 dollars on foam hoping it would absorb some of the vibration and increase my floating ability only to find out I could have reused the Styrofoam blocks that were there...........I think I am gonna cry now.........leave me alone.

Maybe in 15-20 years when I redo this I will use the noodles to save money.

Re: need help with foam problem

redeye1962 said:

Oh Great, After I spent 150 dollars on foam hoping it would absorb some of the vibration and increase my floating ability only to find out I could have reused the Styrofoam blocks that were there...........I think I am gonna cry now.........leave me alone.

Maybe in 15-20 years when I redo this I will use the noodles to save money.

Click to expand...

That is a age old misnomer....two part poly foams cannot absorb water...Now any person with any kind of proof plz post as much......Along with the mfg of the foam...the absoration rate and time lines....Old wives tales going on here....

Re: need help with foam problem

From what I have seen in the posts it appears the foam can obsorb water because of how some folks have to pull out the old wet foam. I am willing to bet the boat has been sitting exposed to the elements for a period of time and the foam has had the opportunity to absorb moisture. I am hoping that is the case.

Re: need help with foam problem

I dont know what kind of foam I had in my 18' Las Vegas Sierra Tri-Hull but the floor was soft so I pulled it up. What I found was water logged foam and a couple of cross members that were not in the best of shape. I am currently sanding the bottom of the inside hull in prep for redoing the inside. I plan on using 3m foundation sheet foam that I can cut to shape. It does not absorb water and the water will easily drain down to the exit hole in the transom. I may even have a small gastank made to fit so that I will not have to carry those big red gas cans. Who knows, first is the sanding. Redfury has given lots of advice to me on this. He and his friends are great assets. I would recommend using a foam that will not absorb water. Not all are the same and not all claims of "will not absorb water are true". Research a bit on here and make an informed decision. Good Luck to you all.

Vr,

Sailor77.7

Re: need help with foam problem

Folks,
My primary line of work is roofing consulting and we work with "foam" insulations. This is what we know-The white bead board, or expanded polystyrene, when introduced to heat and water will absorb huge amounts of moisture. The pink and blue boards, or extruded polystyrene, will not.

I'm planning on yanking the floor out of my recently purchased 66 Sunchief this winter, so at this point, I don't have a clue as to what type of foam is in there, but if it's expanded insulation, it's coming out, wet or dry.

When folks first started using the expanded insulation, there really hadn't been any testing along the lines of heat induced water absorbsion, so everyone just assumed all was OK. We've done roof remediation jobs where the expanded was installed over the single ply roof membrane as a protection and tapering course. When some of those large blocks were installed, one guy could carry a peice as large as a small car. When it came out, four men could barely carry a 8'x8'x12" sheet
Just my 2 cents!
NB