blue foam question

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200racing
Posts: 430
Joined: 25 Mar 2011, 20:09
Location: central,AL

blue foam question

Post by 200racing » 22 Feb 2012, 12:36

how much flotation does a 4x8x.5 sheet of the blue foam boards have? has any one tested this or seen a number?
g3 pf 175 converted to multi species assault boat.
http://www.tinboats.net/forum/viewtopic ... 47#p241047


monark 1436 flat bottom w/johnson 9.9 hp. eagle cuda 350 w/gps.minn-kota endura c2 30lb.

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JMichael
Posts: 2926
Joined: 19 Jan 2012, 07:44
Location: Northeast Arkansas

blue foam question

Post by JMichael » 22 Feb 2012, 12:55

I'm using the blue foam in my boat. I just calculate the number of gallons of water it will displace to see what the approximate flotation gain would be. In the case of one sheet that size it should be around 63 lbs of flotation. If you're trying to figure how much you'd need to keep your boat from going to the bottom there is more math involved though, because everything is lighter under water than on the surface and you'd have to calculate that into it.

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200racing
Posts: 430
Joined: 25 Mar 2011, 20:09
Location: central,AL

blue foam question

Post by 200racing » 22 Feb 2012, 13:39

just seeing how much good i had done. i have added 1.5 sheets to my boat in addition to the factory foam.
g3 pf 175 converted to multi species assault boat.
http://www.tinboats.net/forum/viewtopic ... 47#p241047


monark 1436 flat bottom w/johnson 9.9 hp. eagle cuda 350 w/gps.minn-kota endura c2 30lb.

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Bigkat650
Posts: 243
Joined: 29 Nov 2011, 22:39
Location: Upstate NY

blue foam question

Post by Bigkat650 » 22 Feb 2012, 14:02

JMichael wrote:I'm using the blue foam in my boat. I just calculate the number of gallons of water it will displace to see what the approximate flotation gain would be. In the case of one sheet that size it should be around 63 lbs of flotation. If you're trying to figure how much you'd need to keep your boat from going to the bottom there is more math involved though, because everything is lighter under water than on the surface and you'd have to calculate that into it.

Correct. You need to know the specific gravity of the materials your boat consist of, more then just weight. 100lbs of wood and 100lbs of steel require different flotation requirements. I am not sure of the formula, but there are several post about it 'floating' around.

You can find specific gravity of materials here: http://www.reade.com/Particle_Briefings/spec_gra2.html
The formula to determine how much you need to 'float' to keep your boat from sinking is something like:

Material weight / specific gravity of material = negative buoyancy... Then you take the material weight and subtract the negative buoyancy to determine how much of the weight of the material you have to float.

Do that for all the materials that comprise your boat, and that gives you a figure of how much weight you have to actually float in order to keep your boat from sinking. I added an additional 50% to that number, because I wanted to be absolutely sure and factor in for things like batteries, anchors, fishing equipment, etc. 50% is probably overkill, but all things being equal, I like knowing my boat will not sink! :LOL2:
Let your passion be your guide.

Boat Smart--FISH HARD!
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