risking repitition (flotation)

[alden135]

I thought I read a post on flotation regarding foam panels but can't seem to find it now. All I'm looking to find out is how many pounds of boat (out of water) will one cubic foot of pink insulation board float when submerged. Boat had styrofoam from factory (1961 Crestliner) which lasted 40 years so same is going back in. Before you say so I'd use foam but to do so I'd have to go through all the BS of glassing the floor to the hull and such. Right now it's just plywood with i/o carpet screwed to ribs. Foam will be next year when I do a proper retrofit on this boat. I thought I read 100lbs. boat =1 cubic ft. styrofoam. I'm a carpenter and have tons of free closed cell o/c panel material.I guesstimate that the boat motor and gear weigh in approx. at 1300lbs. Any help would as always be very much appreciated. An answer will be welcomed along with the appropriate amount of flack for asking another flotation question. At least I'm not using ping pong balls.

 

[Richard Petersen]

Re: risking repitition (flotation)

1 cubic foot of fresh = 62.5#----- salt=64#-----minus the weight of the cubic foot of the foam. About 4# ? Go to it.

 

[Realgun]

Re: risking repitition (flotation)

As a general rule it is about 60 Lbs per square foot of bouyancy. The boat may weight 15,000 lbs . But it will displace some water and wood floats. So you may only need to hold up 10,000 Lbs. <br />Normally we see 2lb foam is 60 Lbs and 8lb foam is about 56 Lbs of up power.<br /><br />It really depends on the weight of the foam. 1 sq ft of water weighs.<br />1 cubic foot = 7.4805195 gallon [US, liquid]<br />1 gallon [US, liquid]= 8.345 pound (water)<br />so 7.4805195 X 8.345=<br />62.4249352275 Lbs - the weight of the foam board that is 1 cubic ft= lifting power!!!<br />Hope this helps.

 

[alden135]

Re: risking repitition (flotation)

Thanks for the numbers Richard.I'll be starting tomorrow.

 

[alden135]

Re: risking repitition (flotation)

Thanks Realgun. I think I'll be going with your answer of 62.4249352275 rather than Richards wildly inacurate guess of 62.5 lbs. I suppose other variables will need to be taken into consideration such as whether we have eaten lunch or if our sheltie is on board with us. I like this iboats thing

 

[Richard Petersen]

Re: risking repitition (flotation)

As a safety factor , add 1 extra cubic foot for the beer and ice.

 

[alden135]

Re: risking repitition (flotation)

What if i just were to turn my bilge into a large cooler? Ice has bouyancy. Looks like I'll have to run the numbers again.

 

[Richard Petersen]

Re: risking repitition (flotation)

On my Aluminum 16' fishing boat, Lowe put full sized blocks of foam under each bench seat and under the the transom splash tray. Passes USCG.

 

[Chris1956]

Re: risking repitition (flotation)

Folks, As a note of interest, When was the law requiring boats to float level when swamped, implemented?<br /><br />I calculated the amount of foam in the floor of my speedboat will support 150 pounds. The boat is about 600 pounds, and it has a chunk of foam in the bow. With a 300 pound outboard on the stern, she floats nose up, outboard down.

 

[alden135]

Re: risking repitition (flotation)

I've read on this site that boats after 1972 are required to have level flotation. You should be all set with what you have after removing all gear and chucking your motor into the bay.

 

[Richard Petersen]

Re: risking repitition (flotation)

Level. Like the shark has to slide into the boat.

 

[Richard Petersen]

Re: risking repitition (flotation)

Level. Like the shark has to slide into the boat.--------outboards are Not required to float level, only remain a float, nose up is OK.

 

[alden135]

Re: risking repitition (flotation)

Paint your bow red and buy a bell.

 

[beniam]

Re: risking repitition (flotation)

Realgun<br />You sure have a lot of numbers behind your 62.4............ Pounds per cubic foot. Did you forget to round off? Carpenters only measure to the sixteenth of an inch.Did you take into account the temperature of the water? Densest at 4 degrees C., if you are inclined to boat at that temp. Will need more flotation in summer when the water is warm. Batavier