Dinghy
A dinghy is a type of small boat, often carried or towed by a larger vessel. The term can also refer to small racing yachts or recreational open sailing boats. Utility dinghies are usually rowboats or have an outboard motor, but some are rigged for sailing. Because the smaller sailing dinghy responds more quickly to maneuvers, it is more suitable for beginner training in sailing than full-sized sloops.
Contents
Types
Dinghies usually range in length from about 6 to 20 feet (2 to 6 m). Larger auxiliary vessels are generally called tenders, pinnaces or lifeboats. Folding and take-down multi-piece (nesting) dinghies are used where space is limited. Some newer dinghies have much greater buoyancy, giving them more carrying capacity than older boats of the same size.
Most modern dinghies are made of synthetic materials. These require minimal care and do not rot. Inflatable dinghies can be made of fabrics coated with Hypalon, neoprene or PVC.[1] Rigid dinghies are usually made of glass-fiber reinforced plastic (GRP) but injection-moulded one-piece hulls are also available.[2] Other materials for modern rigid dinghies include aluminum, marine plywood and, with the advent of sturdy, UV resistant urethane varnishes, wood. Some wooden dinghies (especially of classic or historical form) are built using the carvel or clinker methods. Favored woods, in order of rot-resistance, are white oak, locust, species of cedar and pine, true as well as African and Asian mahoganies, fir and spruce. Plastic hardware is sometimes used, but bronze and stainless steel are good corrosion-resistant materials for hardware, although stainless steel is subject to crevice corrosion and must be inspected and replaced fairly frequently when used for rigging and some other parts. Working boats may use lower-cost galvanized steel, but the hardware may need to be re-galvanized or replaced eventually.
- Whaleboats are among the classic "pulling" (rowing) boats, with a sharp bow, fine stern lines and a canoe stern. Despite being somewhat more tippy, with less cargo capacity than prams, they row, motor and sail well because of their fine lines. Prior to the introduction of fiberglass as a construction material, dories were more popular because their ease of assembly and, thereby, lower cost.
- Whitehall Rowboats were the water taxis of the late 1800s until the invention of the small gasoline outboard. Considered one of the most refined rowboats for harbor and lake use, Whitehall Rowboats are a descendant of the Captain's Gig which was used for a similar purpose on a naval vessel.
- Dories are sharp-ended boats traditionally made of wood but now also produced in fiberglass or aluminum. They cut the water well, but their initial stability is low, making them feel tippy in flat water; a loaded dory becomes more stable as she is loaded. Dories are not generally used as service boats to yachts; they were used in large numbers in the cod fishing business, launched in numbers from the deck of a schooner hove to on the Grand Banks or other fishing ground. A dory can be landed or launched through surf where a Whitehall may founder.
- Prams are similar to dories but are wider with transoms at both bow and stern. They are difficult to tip and carry a lot of cargo but are slow because of their lack of directional stability, although a keel and/or bilge runners can make a big difference, and even without they will row better than an inflatable.[3] A boat-builder's product description.File:Norwegian pram.jpgA Norwegian pram
- Some inflatable boats have a rigid deck and transom which allows an engine to be used for propulsion. They row poorly and do not tow well because of their blunt bows and large wetted surface, but they are exceptionally buoyant.
- Rigid multifunction self-rescue dinghies are designed to row, motor, tow, and sail. In addition to their proactive lifeboat functionality, these boats serve as everyday tenders and as recreational boats. They are extremely buoyant and/or unsinkable and have great carrying capacity relative to length.
Space issues
On yachts shorter than 10 meters there is usually not enough room for a reasonably sized dinghy. A dinghy is useful to avoid the need for expensive dock or slip space, so owners of small yachts compromise by carrying a small rigid dinghy or deflated inflatable, or by towing a larger dinghy. Space can be saved by storing items in containers or bags that are tied to the dinghy. Dinghies are sometimes used as lifeboats.
Rigid dinghies for small yachts are very small (2 meters), usually with a pram (blunt) bow to get more beam (width) in a shorter length. Larger dinghies are towed and should have reserve buoyancy, an automatic bailer, and a cover to prevent them from being lost at sea. Most masters prefer a tow cable long enough to put the dinghy on the back side of the swell to prevent the dinghy from ramming the transom of the yacht.
Inflatables are inconvenient to tow and take extra time to inflate but are very compact and fit easily into place while at sea. Space can also be saved by using a sectional two-piece rigid dinghy that is towed while in harbor and disassembled into two nesting pieces while off-shore; typically the bow section fits inside the stern and is stored upside down on deck. There are several types of collapsible rigid dinghy that dismantle into a series of flat panels for easy stowage.
Inflatable tubes can be fitted to an existing hard dinghy, increasing buoyancy and stability.
Hardware
A dinghy should have a strong ring on the bow. The ring secures the painter (the line that anchors the boat to a dock), and is used for towing and anchoring. Ideally, the dinghy should also have two other rings (one on each side of the stern transom) which, with the bow ring, are used for lifting and securing the dinghy for stowage.
The only other essential pieces of hardware are oarlocks (also known as rowlocks). Conventionally, a dinghy will have an oar on each side. A single sculling oarlock on the transom is less common, but requires less space; a sculling oar moves back and forth, never leaving the water, as used on a sampan.
The dinghy is generally carried inverted amidships on yachts, keeping the yacht balanced. It is useful for a dinghy carried this way to have handholds built into the bottom, making launching easier and providing handholds on deck.
Most yachts launch their dinghies by hand or with a simple lifting tackle rigged from the main mast. Another arrangement, davits over the transom, is convenient and elegant, but sailing in a heavy following sea could cause the loss of a dinghy. If a dinghy is towed, an extra line with a loop in the end (known as a lazy painter) can be attached to a dinghy so that if the towing line breaks, there is a line to grab with a boat hook. This makes retrieval easier at sea, especially if the boat is partially swamped.
Dinghies often have names and numbers. On hard dinghies these are usually on the bow, on inflatables on the inside of the transom.
Propulsion
Oars
Conventional dinghies are powered by rowing with one set of oarlocks for each thwart (seat). In some models, sliding thwarts allow far more powerful rowing while in others, a removable thwart can permit standing rowing. A single sculling oar with an oarlock on the rear transom can be a compact emergency oar.
Motor
Another option is an outboard motor. Two horsepower per meter can reach hull speed. Ten horsepower per meter will put a flat-bottomed dinghy on plane. A 10-foot (3.0 m) dinghy with a hard V-bottom hull and a fifteen horsepower outboard can reach speeds of 25 mph (40 km/h). The gas tank is usually placed under the rear thwart. Engines always swing up so the dinghy can be grounded without damage. Since the transom may need to be cut down for the engine to fit properly, an engine well should be used to prevent low waves from splashing over the transom and flooding the boat.
Sail
A typical sailing rig for a dinghy is a gunter with a two-piece folding mast stepped through a thwart and resting on the keel. It is raised by pulling a rope. A single-sailed gaff rig is usually preferred over a marconi (with a triangular mainsail and jib) because a gaff rig is simpler and has a lower center of force. The bottom of the main sail can be untended (no boom) in order to avoid hitting the passengers with a spar. Sprit rigs also have no boom, and the advantage that the sail can be brailed up out of the way against the mast when rowing or motoring. Recently, power kites have become available. They are more compact, help maneuver and are easier to install, but require more attention.
Traditional working dinghies have a lee board that can be hooked over the side. This does not split the cargo space. A sailing rudder is usually tied to a simple pair of pintles (hinge pins) on the transom with the bottom pintle being longer so that the rudder can be mounted one pintle at a time. The rope keeps the rudder from floating off in a wave. Both rudders and lee boards have swiveling tips so the dinghy can be landed. Rudders are often arranged so the tiller folds against the rudder to make a compact package.
Racing dinghies usually have a daggerboard or centerboard to better sail upwind. The trunk is in the middle of what would otherwise be cargo area.
Other equipment
Additional equipment that is generally considered necessary or legally required on a dinghy includes:
- life-jackets for every occupant
- a hand-bailer
- a bailing sponge
- a large torch/flashlight
- a mouth-blown horn (not a loud-hailer, but a breath-blown foghorn)
- signal whistle
- signal mirror
- flares
This equipment should be in a bag made of water-resistant materials and tied to a thwart or stowed inside a locker.
Anderson-style self-bailers are also useful for engine-driven and sailing dinghies. These slot-shaped seacocks project into the stream below the hull and open when submerged and moving rapidly. The downside of this solution is that if the boat is beached in sand, it can clog the self-bailers until the boat is inverted and the sand removed. These devices do not replace a hand-bailer as they are only useful if the vessel is moving.
A small anchor can be used to allow the crew of the dinghy to fish or rest. Dinghy anchors are usually either a mushroom shape or a small folding grapple hook with floating rope that will avoid being cut by snags on the bottom. The mushroom is used in locations where the bottom is very muddy while the grapple works better in currents. Some persons prefer a small danforth or plow, the same as they would use on a larger boat, but these have sharp edges, and need to be pulled on to set.
A dinghy should not be able to scratch the mother-boat's paint, therefore a fender made from a length of heavy rope can be tied loosely to the outside of the bulwarks. This also provides a handhold for launching, or for people overboard to climb into the boat. Many modern dinghies have a molded ridge of plastic to replace the rope. A fitted acrylic canvas cover can shed seas or act as a shade or storage cover. Traditionally it toggles to the fender-rope or is suspended from the gunter (small folding mast) but can also be tied to a few points and secured with snaps or velcro. Depending on the design there may be a large locker under a thwart.
See also
External links
- Dinghy classification by ISAF
- Directory of dinghy classes
- World of Boats (EISCA) Collection ~ Dutch Pram Dinghy
References
- ↑ Casey, Don (2007). "Inflatable Boats". Boat Owners Association of The United States. http://www.boatus.com/boattech/inflatables.htm. Retrieved 24 April 2010.
- ↑ "The Walker Bay 8". Walker Bay Boats. http://walkerbay.com/products/rigid_dinghy/dinghy_wb8_construction.html. Retrieved 24 April 2010.
- ↑ http://www.gartsideboats.com/pgimages/7pramvarnish.JPG
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