One comment I have to make is that determining the waterline for any vessel, new build or retrofit, is indeed an exact science. Having done numerous vessels, with and without lines plans available, the projects I have worked on have always been able to paint the waterline pre-launch and float exactly as modeled / predicted. This is for powerboats from 19' to 128'. It takes diligence and attention to detail from the entire team of builders/engineers/craftsman and the owners. There are only excuses when the design waterline is off, a clear sign that a commitment to excellence has not been observed by all the stakeholders during the entire process. The easiest way to monitor a one-off new design is to build the entire project on load scales, with frequent up-dates on the predicted design waterline and monitoring of the inevitable scope creep. This function should be in included in any new build spec.