Weight capacity of 5ft wide U-shaped pontoons at full and half submersion

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christoph8025
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I recently bought some pontoons to build a floating camp on. I was wondering if you guys can give me the weight capacity the pontoons could hold at full submergersion and half?

The Pontoons are 5ft 3 in wide, 3 foot tall and 20 feet long. The pontoos are U shaped. The pontoons will be docked in fresh water if that make any difference.

You guys have answered similar questions like this before so hopefully yall can come through again.

Thank you for all yall help and I can't wait to get some results.

Christopher in Louisiana
 
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A rough guess would be 5×3×20 cubic feet × the weight of a cubic foot of water of about 64 pounds, or 19,000 pounds would be required to submerge one of them.
 
Wow that's awsome. Thanks for the calculation and that just made my day better!
 
I think JDLugosi's answer is a bit premature.

1] JD has assumed the pontoons are rectangular. A 5x3x20 round pontoon will have a smaller volume (though not by that much - he did say rough guess).

2] My bigger concern is: What do you mean U-shaped? That can make a big difference in the derived volume.

Do you simply mean its cross-section is U-shaped? My first thought was that each pontoon was bent into a U like a zodiac inflatable boat.
 
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JDługosz said:
A rough guess would be 5×3×20 cubic feet × the weight of a cubic foot of water of about 64 pounds, or 19,000 pounds would be required to submerge one of them.

Less of course, if you are floating in light sweet Louisiana crude. ;))

..
 
The pontoons are not made in the shape of an U. I just meant the cross section of the pontoon resembles a U.

Lets not even get into the OIL BLOW OUT! BP is a joke! They are killing our way of life and our wetlands and a entire ecosystem. And no one outside of the state seems to be worried about it. We supply 34 percent of the whole United States with entergy and no one seems to be worried about that either!

But anyway...

Chris in Louisiana
 
Creator said:
Less of course, if you are floating in light sweet Louisiana crude. ;))

..

OK, that's funny.
 
christoph8025 said:
The pontoons are not made in the shape of an U. I just meant the cross section of the pontoon resembles a U.

Lets not even get into the OIL BLOW OUT! BP is a joke! They are killing our way of life and our wetlands and a entire ecosystem. And no one outside of the state seems to be worried about it. We supply 34 percent of the whole United States with entergy and no one seems to be worried about that either!

But anyway...

Chris in Louisiana

that's pretty close to rectangular so I think 19,000 pounds is a very reasonable estimate.
 
DaveC426913 said:
2] My bigger concern is: What do you mean U-shaped? That can make a big difference in the derived volume.

I supposed it to be a "rounded corner rectangle", not a substantially smaller shape. In any case, I figured by showing the work used to compute it, it would help him see how to do it, or at least serve as a strawman to start refining a better answer.