LOA, beam and draft are the first line of a boat's particulars.
LOA, length overall, is the length from the foremost part of the boat to the aftermost. The US definition in 33 CFR 183.3 measures it in a straight line, parallel to the centerline, and leaves out fittings such as bowsprits and outboard brackets. LWL, the length at the waterline, is shorter on most boats and is the figure that sets hull speed.
Beam is the greatest width. The same rule measures it between the outer sides of the boat, leaving out handles and similar fittings.
Draft is how deep the boat sits below the waterline at its deepest point, usually the keel or the propeller. It changes with load.
Why surveyors care
LOA sets the price. Survey fees are usually quoted per foot of length, so the survey quote calculator starts from it. It also decides which rules apply, and the insurer will check it against the listing. Beam and draft decide where the boat can be hauled and berthed.
In the report
Record each dimension and say where it came from. "LOA 11.9 m (39 ft), builder's specification. Beam 3.9 m. Draft 1.95 m, deep fin keel."