Q. The only information that I have on displacement for my yacht comes from original design specification. How can I update that to a current ‘as raced’ weight?

A. Designers and builders typically provide displacement data referenced to the ‘design waterline’ that most often resembles a ‘light ship’ condition, with empty tanks and minimal food and gear. The weight added in equipping and provisioning for coastal cruising can increase that displacement by 10% or more. The boat hauling equipment in some yards can provide a boat weight, but these weights are typically not especially accurate, and should be used as a rough reality check only. If a displacement is declared that is significantly heavier than the original designer/builder spec, the declarations for LWL and draft (DM) need be longer and deeper, respectively, by appropriate amounts.