aero marine pour foam

[CentralOregonBum]

have you used this? Should I get #2 or #4 density? Thanks.

 

[jigngrub]

Have not used it, but pour foams are the same. There are much cheaper brands that are the same thing, do a google search for expanding urethane foam for competitive prices.

2 or 4 lb. depends on where you're going to use it and what you're going to use it for. 4 lb. is stronger and will support more weight, it's also more water resistant.

Something you should know before using pour foam is that it requires warm temperatures to work with to get the full expansion, and when I say warm it probably means hot to you. Temperatures need to be at least 80*F to get good expansion and 85*+ for full expansion. Trying to install expanding foam in cool or cold weather is a waste of money. You'll be money ahead to use the extruded polystyrene rigid sheet foam like the pink Owens Corning or the blue Dow brand sheet foam.

 

[64osby]

More info needed. Pictures would help.

Is this aluminum or fiberglass? Does the hull have stringers / ribs? Is there floor support besides the foam? Did it have pour in foam before?

2lb foam is for flotation. 4lb for is structural and will support the floor and stiffen the hull.

 

[jbcurt00]

To be clear, Jig you meant the 4# foam will support more weight like standing on it while on the deck its supporting, not that as flotation foam its support (float) more weight then the 2lb, correct?

 

[jigngrub]

To be clear, Jig you meant the 4# foam will support more weight like standing on it while on the deck its supporting, not that as flotation foam its support (float) more weight then the 2lb, correct?

Yup, it won't float more weight than 2 lb but it'll offer more structural support for the boats structure as in supporting decking and hull support. 4 lb. is also recommended for below deck fuel tank support too.

4# is a better foam, but it costs twice as much as 2# and in some cases it isn't worth the extra money unless you want the added peace of mind of being more water resistant.

 

[ondarvr]

I don't know of any boat companies that use 4#, twice the weight and cost and it still succumbs to the same challenges from water and age, it does last a bit longer though. When companies use foams denser than 2# they normally use it in sheet form as a core.

 

[gm280]

As long as it is closed foam cells, It doesn't matter. However a 2lb mix and pour foam offers more buoyance then 4lb mix and pour foam. the 2lb and 4lb foams refers to the weight per 1 cubic foot size. If you keep water intrusion out of a one cubic foot area, you have received the buoyance from that lack of weight of water that would otherwise fill that space. So 2lb foam offers more then 4lb foam. Simple math!

 

[jigngrub]

Product description for 2# foam from a retailer:

[SIZE=+1]2 LB [/SIZE]Density Urethane Foam (U.S. Coast Guard Compliant Marine Foam)

[SIZE=-2]Common Applications: Our 2LB density marine foam is recommended for void filling in nonstructural applications. This product can be poured underneath decks and inside cavities where a lightweight flotation foam is needed to provide buoyancy. This foam has been tested in accordance with U.S. Coast Guard Regulation # 33 CFR 183.114 . This foam is approximately 95-98% closed cell which resists absorbing water, however continuous water submersion can eventually lead to loss of buoyancy over a period of years. We recommend this product strictly for flotation applications.[/SIZE]

Product specifications for the above 2# foam:

[SIZE=-2]Product Information: Free Rise Density: 2.0 lbs per cubic ft. Expansion Rate: Approx. 25-30x Liquid Volume Buoyancy (flotation): 60 LBs per Cubic Ft.[/SIZE]

[SIZE=-2]*Physical Properties: Parallel Compressive Strength: 40 psi Tensile Strength: 30 psi Shear Strength: 30 psi Flexural Strength: 50 psi[/SIZE]

Product description for 4# foam from the same place:

[SIZE=+1]4 LB[/SIZE] Density Urethane Foam

[SIZE=-2]Common Applications: This 4LB density foam is suited well for most flotation applications that require more support than the 2LB offers. This foam is recommended to be used when supporting gas tanks and some deck areas. Choose this density if you feel that the foam will be required to withstand minor to moderate loads. [/SIZE]

Product specifications for the above 4# foam:

[SIZE=-2]Product Information: Free Rise Density: 4.0 lbs per cubic ft. Expansion Rate: Approx. 15x Liquid Volume Buoyancy (flotation): 58 LBs per Cubic Ft.[/SIZE]

[SIZE=-2]*Physical Properties: Parallel Compressive Strength: 90 psi Tensile Strength: 110 psi Shear Strength: 70 psi Flexural Strength: 120 psi[/SIZE]

As you can see from the specs, the 4# only floats 2lbs. less than the 2# per square foot... but is a much stronger foam.

 

[ondarvr]

The general idea in boat design is to not depend on something as fragile as pour foam for structural purposes, just use it as a floatation aid. So the added cost and weight doesn't really add much value. I wouldn't use it to bed metal fuel tanks, it tends to hold moisture cause corrosion.

I forgot to say, if the weight and price aren't a concern then there's no down side.

 

[gm280]

jigngrub, You posted the exact same specs I was talking about. While 2lb mix and pour foam does offer 2lbs more flotation per cubic foot as I stated, it is also half the price of 4lb foam. And if you are only doing one cube foot area, I'd go for the 4lb foam without question. But once you add up the total cost verses floatation for an entire boat, the cost and flotation differences certainly do add up. That was all I was saying. Each person has to do their math for flotation and cost comparison as to which is the better for them. I know I will be using the 2lb mix and pour foam. Because I know my substructure will not be compromised and need 4lb to fill in the inadequacies... JMHO!

 

[CentralOregonBum]

Thanks to everyone.... !!!! Your posts answered all the questions I had bouncing around in my head.

 

[kcassells]

Don't forget to add limber holes for drainage and air.