What lb density of foam?

[lime4x4]

I have to replace the foam in searay cruiser. How do i determine the lb density of the foam needed?

 

[erikgreen]

Re: What lb density of foam?

Standard for floatation is 2lb/ft3, or if the foam is partly structural 4lb/ft3.

Higher densities are for special purposes or strong structure only.

Probably you want the 2 lb, almost all small boats use that.

Erik

 

[lime4x4]

Re: What lb density of foam?

Well my boat is 27 feet long and weighs around 7000 lbs

 

[Bob_VT]

Re: What lb density of foam?

2 lb and higher density 4 lb have the same flotation characteristics ........

If you needed structural 4 lb you would know. Now keep in mind that foam is VERY temperature sensitive and if attempted in our lovely cold weather it may not react and expand the way it should ..... costing you more in the long run.

 

[mikezohsix]

Re: What lb density of foam?

Check out the how to sticky at the top of this forum.

You'll need approaching 100 cubic feet of foam to float 7000 pounds.
Not sure if you need, or really want to do that.

What do you need the foam for, structure, or floatation?

 

[lime4x4]

Re: What lb density of foam?

Actually according to the coast guard i don't require flotation foam cause my boat is over 22 feet long. I was just going to put it back in. I removed it cause it was wet.I don't think it was structual . From my stringers out i have shelves that had foam under them. I removed 3 contractor size garbage bags of wet foam. I was thinking of just leaving the foam out.

 

[ezmobee]

Re: What lb density of foam?

In my boat, I am going to put in as much as I can. Theorizing that if the worst happens I may at least have something semi-floating to hold on to. I gotta say though, on a boat the size of yours, I wouldn't bother. There's probably less chance of a sinking and it's doubtful whatever you could put in there would make much of a difference anyway. Just my opinion (no basis in fact )

 

[lime4x4]

Re: What lb density of foam?

That was my line of thinking as well. The size of my engine compartment and mid berth compartment. Would very easily hold over a 1000 gallons of water. While the cabin would hold several thousand gallons of water. So if i would rip a hole in the hull. I'm pretty sure the foam i removed wouldn't really keep the boat afloat. If anything the foam might help stiffen up the hull some. I have 2 1500 gph bilge pumps as primary and 2 1500 gph bilge pumps as secondaries. i think as long as the batteries hold up that would a do a better job of keeping the boat afloat for a little while. Then again i could be wrong.