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daggerboard
A keel-like device that is manually raised and lowered vertically without using a hinge.

davit
A small crane used to hoist a boat or dinghy or other object.

daysailer
Small, open sailboat sometimes raced or short-distanced cruised, primarily used for recreational sailing.

day sailing
To go sailing for a few hours on a small, open sailboat.

dead ahead
Directly ahead of the bow.

deadrise
Degrees of V-shape hull angle measured at the transom of planing powerboats.

deck boat
Blunt-bowed power boat generally characterized by an open deck and generous passenger seating.

deep-V
A hull shape characterized by a sharp deadrise, typically more than 20 degrees.

depth sounder
Electronic sonar device that displays water depth.

deviation
The amount of error from displaying magnetic north in a boat's compass caused by the boat's own magnetic interference.

differential GPS (DGPS)
A highly accurate global positioning system (GPS) that utilizes a differential radio beacon and receiver to compute and correct the error of all visible satellites sending data to a conventional GPS unit.

dinghy
A small sailboat often raced that can be sailed on and off a beach. Also a tender, either rowed or equipped with power, used to go to and from a larger vessel.

dinette
A small dining area usually consisting of a table and facing bench seats; it can often be converted into a berth.

direct drive
An engine configuration in which the drive shaft runs in a straight driveline through the bottom of the hull.

displacement
The weight of water displaced by a hull. Also, a type of hull that smoothly displaces water as opposed to riding on top of it.

displacement hull
A hull shape designed to run through water rather than on top of it in the manner of a planing hull.

downrigger
A gunwale-mounted weighted line device used for deep-water trolling.

draft
Vertical distance a boat penetrates the water.

drogue
A parachute-like sea anchor.

dry weight
Weight of the boat without fuel and fresh water.

dual-console boat
A type of boat with twin dashboards separated by a centerline walk-through deck leading to the bow.