Mars Bar--Yacht designers calculate the CB, the center of balance and the CE, center of effort. When one is in front of the the other center it effects the helm. Another way of saying what SkiprJohn wrote. You are also adding addition weight, your new floor and cabin height, to your Hughes which will effect the CB. One result of the additional weight will cause a greater wetted surface, hence more resistance through the water
. Greater wetted surface also results when a light displacement hull
is loaded with stores for a long cruise
. How your Hughes will react is an unknown unless you pay a yacht designer
to do all the calculations. Of course since yacht design is not an exact science it becomes an educated guess. If you have never sailed the boat
, then you have no way of gauging if the sailing characteristics have substantially changed.