There's been a lot of discussion about materials and techniques. I suggest
that regulars on this forum will be of limited assistance with these
"engineering" aspects of the problem.

The hull design, on the other hand, is an interesting question.

The boat must float with a heavy load, presumably at rest in a smooth pool,
and have a maximum volume of 1 cubic foot. How will the weight be
measured? I would guess, by adding small blocks or balls of cargo, until a
gunwale goes under, and the craft sinks.

Will the cargo be very dense, such as lead blocks? In that case, you will
want the weight to be concentrated at the bottom center, as ballast. A very
deep hull, (ideally a longish cylindrical shape, with one end closed - as
you add weight, stability increases.) On the other hand, if it's too deep a
hull, it will lack stability when unballasted, and perhaps fail at the
outset.

If the weight to be added is a relatively light (low-density), the hull
shape would be very different, perhaps towering above the gunwales.
Stability will be a limiting factor. Perhaps a catamaran form? What about a
"floating drydock" approach, where the cargo is on a platform at the BOTTOM
of two (sealed?) pontoons - as it is loaded, the platform will submerge, and
cargo will contribute to the buoyancy...

--
Sal's Dad


wrote in message
oups.com...
I have to build a cement boat that will hold as much weight as
possible. It must be made completely out of cement, no styrofoam, wood,
or anything that would provide buoyancy. It can be 1 cubic foot
maximum. How would I go about doing this??