Displaced weight vs Dry Weight
I always thought that why there is a displacement and a weight is that when a boat is designed the statistics are figured out to be whatever they may be for any given boat. Ie. this is how the boat will perform.This being designed displacement. Now, When you load the boat with water, fuel stores or just stuff you might have, this extra weight will have an effect on it''s performance and will vary from it''s designed statistics. This being weight.
I don''t know exactly how much truth there is to this but it makes sence to me.