YPI Yachting Glossary
All the yachting terms explained...from A to Z
A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
| D signal | safety signal, "Keep clear of me. I am maneuvering with difficulty." |
| dacron | A synthetic polyester material. |
| dagger board | A type of centre board that adjusts vertically in the well. |
| danbuoy | A marker that is attached to a lifebuoy |
| danforth anchor | A brand of lightweight anchor. It has pivoting flukes that dig into the ground as tension is placed on the anchor. It does not have a stock. |
| danger zone | The area encompassed from dead ahead of your boat to just abaft your starboard beam. You must stand clear of any boat in the "danger zone". |
| davit | A device that projects beyond the side of the boat to raise objects from the water. Typically a single davit is used on the bow of a vessel to raise an anchor, and a pair are used on the side or stern of the vessel to raise a dinghy. |
| daybeacon, daymark | A navigational aid visible during the day. In the United States and Canada, square red daybeacons should be kept on the right and triangular green daybeacons should be kept on the left when returning from a larger to smaller body of water. Also see can and nun buoys. |
| daysailer | A small boat intended to be used only for short sails or racing. |
| dayshape | Black diamond, ball, and cone shapes hoisted on vessels during the day to indicate restricted movement ability or type. For example three balls means aground. |
| dead ahead | A position directly in front of the vessel. |
| dead astern | A position directly behind the vessel. |
| dead before | Running with the wind directly behind the boat. |
| dead downwind | Sailing straight with the wind. |
| dead reckoning | A method of determining position by making an educated guess based on last known position, speed and currents. |
| dead-eyes | Blocks in the shroud rigging used to adjust tension |
| deadhead | a floating log |
| deadlight | Fixed ports that do not open, placed in the deck or cabin to admit light. |
| deadrise | The measurement of the angle between the bottom of a boat and its widest beam. A vessel with a 0º deadrise has a flat bottom, high numbers indicate deep V shaped hulls. |
| deck | The surface on the top of the boat that people can stand on. |
| deck plate | a metal plate fitting on the deck that can be opened to take on fuel or water |
| deck stepped | A mast that is stepped (placed) on the deck of a boat rather than through the boat and keel stepped. The mast of a deck stepped boat is usually easier to raise and lower and are usually intended for lighter conditions than keel stepped boats. |
| deckhand | A crew member responsible for cleaning the deck, and an overall boat maintenance. |
| deckhead | The underside of the deck, viewed from below (the ceiling.) |
| delaminating | A failure of the bond between either of the hull's outer and inner skins, and the sandwich spacing material in between-allowing either of the two outer layers to become unstuck from the core. |
| depression | Low-pressure area in meteorology |
| depth sounder | An instrument that uses sound waves to measure the distance to the bottom. |
| derelict | Any abandoned vessel. |
| design waterline (DWL) | Also length waterline or load waterline (LWL) - The length of the boat where it meets the water when loaded to its designed capacity. |
| deviation | See magnetic deviation or compass error. |
| dew point | The point of temperature and air pressure at which water vapor forms mist or fog |
| DGPS | Differential Global Positioning System |
| dinghy, dink | A small boat used to travel from a boat to shore, carrying people or supplies. Also known as a dink or tender. |
| dismast | The loss of a mast on a boat. Generally this also means the loss of some or all of the ability of the boat to sail. |
| displacement | The weight of a boat measured as a the weight of the amount of water it displaces. A boat displaces an amount of water equal to the weight of the boat, so the boat's displacement and weight are identical. |
| displacement hull | A type of hull that only floats, even when in motion, as opposed to a type of hull that allows a boat to skim across the surface of the water. See planing hull. |
| displacement speed | Also hull speed. The theoretical speed that a boat can travel without planing, based on the shape of its hull. This speed is 1.34 times the length of a boat at its waterline. Since most monohull sailboats cannot exceed their hull speed, longer boats are faster. |
| distance made good | The distance traveled after correction for current, leeway and other errors that may not have been included in the original distance measurement. |
| distress signals | Any signal that is used to indicate that a vessel is in distress. Flares, smoke, audible alarms, electronic beacons and others are all types of distress signals. |
| ditty bag | A small bag. |
| dive flag | A red flag with a white stripe. Flag displayed by boats if they have divers in the water. |
| dividers | A navigational tool used to measure distances on a chart. |
| dock | An platform where vessels can make fast. The act of securing a boat in such a place. Docks are often subdivided into smaller areas for docking known as slips. |
| documentation | Licenses or registration papers for a vessel. Types of documentation vary depending on the country, vessel size and purposes. |
| dodger | A cover attached to the top of the cabin at the front of the cockpit. Dodgers help shelter the cockpit from wind and water. |
| doldrums | An area between the weather systems of the Northern and Southern Hemispheres characterized by frustrating light winds, major shifts in wind direction and sudden violent squalls. |
| dolphin | A group of piles driven close together and bound with wire cables into a single structure. |
| dorade vent | A type of vent designed to let air into a cabin and keep water out by the use of baffles. |
| double ender | boat with a pointed bow and stern |
| double-braid | A line consisting of a braided inner core and a braided outer sheath. |
| douse | To drop a sail quickly. To extinguish flames. |
| down helm | To steer a sailboat toward the wind. |
| downhaul | A line used to pull down on a spar or sail. |
| downwind | In the direction the wind is blowing. |
| draft | The depth of a boat, measured from the deepest point to the waterline. The water must be at least this depth or the boat will run aground. Also describes amount of curvature in a sail. |
| drag | The resistance to movement. |
| dragging | Description of an anchor that is not securely fastened to the bottom and moves. |
| draw | Draft. The depth of water that a boat requires to stay off the bottom. A vessel "draws" a certain amount of water. |
| drawbridge | A bridge that can be raised vertically to allow boats to pass underneath. |
| drift | The velocity of a current. |
| driving force | Force produced by catching wind in a sail and transmitting the energy into a the mast |
| drogue | Any object used to increase the drag of a boat. Typically shaped like a parachute or cone opened underwater, drogues slow a boat's motion in heavy weather. Also see sea anchor. |
| dry dock | A dock where a boat can be worked on out of the water. The boat is usually sailed into a dry dock and then the water is pumped out. |
| dry rot | Used to describe the decay of wood. A misnomer, dry rot is actually caused by moist conditions in fresh water. |
| dry sailing | When boats, especially smaller racers, are kept on shore instead of being left anchored or moored, they are dry sailed. the practice prevents marine growthon the hull and the absorption of moisture into it. |
| dry storage | Storing on land. Many small boats are placed in dry storage over the winter. |
| ducts | Tubes used to move air, such as to ventilate an enclosed area. |