One of the design constraints placed on hull design was the maximum core hull length. While shipping options drove this design constraint, it meant that the core hull could be periodically float tested, and its true vs. calculated displacement checked, in a bathtub.
Here you can see our first float tests of the core blacktip hull in a bathtub. While our first tests were done in a bathtub out of necessity, it worked out so well that we will now do all our initial testing this, only renting time at a pool or going to a dock when the tests require open water.
Interestingly, version of the hull had a bunch of places for adding trim weight in case the actual buoyancy varied from calculations. They turned out not to be needed. This test was conducted without any hardware added to the hull, and the hull displacement as simulated was within the margin of measurement error from our measurements.