Bouyancy of float

[Float builder]

I'm a first time float builder and I am wondering if anyone out there can answer my question.
I need to know how big the float has to be, (length, width etc.), to carry 2000lbs on water?

[alan white]

If the float is to be half-submerged, it has to be double the displacement of the 2000 lbs plus its own weight. If it weighs 500 lbs, then the calculation is for a water volume weighing 5000 lbs.
A cubic foot of fresh water weighs 62 lbs approx., so dividing 5000 into 62 gives about 81 cubic feet enclosed volume.
Now the length to width/height requirements must be known. Guessing at one foot height, 8.1 ft wide by 10 ft long will float 2000 lbs at half- submersion if the float hull itself weighs 500 lbs.
Its design displacement will be 2500 lbs, and its payload 2000 lbs. Its weight will be 500 lbs, and its reserve bouyancy 2500 lbs.

Alan

[marshmat]

Or, if you use metric units, things get a bit easier.....
Say you want to hold up 1000 kg (one tonne).
Say the float itself will weigh about 200 kg. So that's 1200 kg total.
Fresh water has SG=1, thus the submerged volume is 1200 L.
Using Alan's suggestion of half-submerged we have 2400 L or 2.4 cubic metres total.
That could be 1 by 1.2 by 2 metres, or 4 by 1 by 0.6, etc.