Dinghy

A dinghy is either a small utility boat used to tend a larger boat, or it is a boat developed from these tenders but now used in its own right as a form of leisure sailing.( See Dinghy sailing.)

This article concentrates on dinghies as tenders for larger boats. Most often, dinghies are rowboats, or have small outboard motors. Sometimes a small sailing rig is available.

Dinghies are extremely important. Nothing can make a yacht so inconvenient to service as a wrong-sized dinghy. Almost as many yachtsmen are killed in their dinghies as in their yachts. This happens because many people attempt to operate their dinghies in states of exhaustion or drunkenness that they would never dare on their main boat. Therefore, safety is extrmely important.

Dinghy types

Dinghies range in length from 2m up to about 6m. Larger auxiliaries are called pinnaces or lifeboats. The best size of dinghy for most yachts is about 4m, because this can carry a complete family or a family's provisions for a month.

The favorite modern material for a dinghy is glass-fiber reinforced polyester (GRP), because it requires the least care, and never rots. Water penetrating the outer coat can cause blistering and delamination. This can be prevented with a barrier coat of epoxy resin.

Aluminum and marine plywood also work well. Carvel and clinker-built wooden dinghys are beautiful, and have finer lines and better handling, but they are usually somewhat heavier. Favored woods, in decreasing resistance to rot, are locust, mahogany, fir and spruce. Modern urethane varnishes are sturdy and resist UV.

There are three common shapes for rigid dinghys.

Whaleboats are the classic premium rowboats, with a sharp bow, fine lines and a flat transom. They tip slightly, row, motor and sail the best because of their fine lines, but have less cargo capacity than prams.

Dorys are sharp-ended boats made from sheets of wood or aluminum. They cut the water well, but tip easily.

Prams are like wide dorys with flat bows. They don't tip and carry a lot of cargo, but don't cut the water well.

Fiberglass boats are all molded, so whaleboats have supplanted dorys, which were once less expensive because they were easier to build.

For inflatables, the Zodiac-type inflatable, with a rigid deck and transome, have proven superior for engines. They row and sail about as poorly as prams because of their blunt bows. Inflation makes them tough, with large reserves of buoyancy.

Folding and take-down multipiece dinghies also exist.

Bronze is the best material for hardware, followed by stainless steel. Working boats usually use galvanized steel, and replace the hardware every few years.

The Dinghy Problem

On yachts shorter than 10m there is not enough room for a reasonable dinghy, but there is a genuine need for one, because anchorages are far less expensive than slips or dock space.

Owners of small yachts compromise. They use a small rigid dinghy, tow a larger dinghy or deflate an inflatable.

Rigid dinghys for small yachts are very small (2m) dinghys, usually with a pram (blunt) bow to get more beam (width) in a shorter length.

Larger dinghies can't be lept on deck, so they are towed. A towed dinghy should have reserve buouyancy, an automatic bailer and a cover, or it is likely to be lost at sea. Most masters prefer a tow long enough to put the dinghy on the back of the swell, to prevent the dinghy from ramming the transom of the yacht.

Inflatables take extra time to inflate, and tow badly. During an ocean passage, they fit easily in their place.

Some owners have experimented with a two-piece rigid dinghy that's towed in harbor and disassembled into two nesting pieces while off-shore. When the joining method was sturdy, these reported good results.

Essential hardware

A dinghy should have a strong ring on the bow, bolted through the keel in a position that will not score the yacht's deck when the dinghy is inverted on deck. The bow ring is used for the painter (tying to a dock), towing and anchoring.

The dinghy should also have two other rings, on each side of the stern transom.

All three rings are for lifting, and securing the dinghy for stowage.

The only other essential hardware are the oarlocks (see rowing, below). The boat can struggle along with a single sculling oarlock atop the transom. The oarlocks should have ropes and storage pockets, or permanent mounts.

The dinghy is generally inverted midships on yachts to avoid unbalancing the boat, and to keep the dinghy secure from waves. Inversion keeps water out of the dinghy. Most yachts launch their dinghies by hand, or with a simple lifting tackle rigged from the main mast. Davits over the transom are convenient and look good, but sailing in a heavy following sea can cause the loss of a dinghy.

When the dinghy is inverted amidships, many yacht owners prefer it to have hand-holds on its bottom. These help launch it, and also provide more handholds on deck.

On all dinghys a name and identifying numbers should be stenciled to prevent theft. Outboards should be locked to the dinghy with a security cable. The dinghy should be locked to its place when stored on deck in a harbour, or alongside a public dock. The motor should be secured by a security cable.

Propulsion

Conventional dinghies are rowed. Usually there is one set of oarlocks for each thwart (seat). Sliding seats allow far more powerful rowing. A removable thwart can permit standing rowing. A sculling oar can substitute for several oars on a dinghy normally moved by other power. A nice refinement is to place a notch or oarlock in the transom (rear wall) for a sculling oar, with a tie-down so the scull need not be pushed down by hand.

Outboard motors are also popular, though much more expensive. Engines always swing up so the dinghy can be grounded without damage. A horsepower per meter of length can move a dinghy faster than oars. Two horsepower per meter can reach hull speed. Ten horsepower per meter will put a flat-bottomed dinghy on plane. Conventionally, the gas tank is placed under the rear thwart.

The transom should not be cut down for the engine. If it is, then an engine well must be present. This prevents the boat from flooding from a low wave over the transom.

The typical sailing rig for a dinghy is a "gunter." This is a two-piece folding mast that can be stepped through a thwart and rested on the keel. It is raised by pulling a rope. Generally, it resembles a single-sailed gaff rig rather than a marconi with a triangular mainsail and jib. The gaff rig has a lower center of force and a simpler rig. The bottom of the main sail is usually untended (no boom) in order to avoid hitting the passengers with a spar. A new, compact possibility is a sailing kite.

Sailing dinghies for racing usually have a daggerboard or centerboard to better sail upwind. The trunk for these is usually in the middle of the dinghy's cargo area. Traditional working dinghies have a lee board that can be hooked over the side. A lee board does not split the cargo space.

A sailing rudder is usually seized (tied by rope) to a simple pair of pintles (hinge pins) on the transom. The bottom pintle should be longer so the rudder can be mounted one pintle at a time. The rope keeps the rudder from floating off in a wave.

Rudders and centerboards always have swiveling tips so the dinghy can be landed. Rudders often are arranged so the tiller folds against the rudder to make a compact package.

Other equipment

A dinghy should have at least a sculling oar, life-jackets, a hand-bailer, a bailing sponge, a large flashlight, a horn run from bottled air, signal whistle, signal mirror and flares. This equipment should be in a bag made of waterproof materials tied to a thwart or inside a locker.

Anderson-style self-bailers are useful for engine-driven and sailing dinghys. These are slot-shaped seacocks that project into the stream below the hull. They are opened when submerged and moving rapidly.

A dinghy's crew can rest or fish if it has a small anchor. A rode (anchor rope) made of floating rope can't be cut by snags on the bottom. The traditional anchor is a mushroom, which does well in muddy bottoms. Folding grapnels weigh less and work in currents, but don't anchor quite as well in mud.

A dinghy should not be able to scratch the mother-boat's paint. The traditional fender is a length of heavy rope seized (tied by small rope) to the outside of the bulwarks (top of the sides), and slightly loose to provide a handhold for launching, or men overboard. Many modern dinghies mold in a ridge of soft plastic.

Many people prefer a dinghy to have a fitted cloth cover which can shed seas, or act as a shade, cuddy, cargo cover or storage cover. Traditionally it would toggle to the fender-rope or be suspended from the gunter (small folding mast). Now it would be tied to a few points and secured with snaps or velcro. Acrylic canvas is a fine modern material that's resists the sun. A couple of battens and windows to make it a tent are wonderful.

A dinghy should have a locker to secure its equipment. Traditionally this is under a thwart with a bronze padlock that's opened at sea. The locker is generally arranged so the boat's painter (rope to the front ring) can be locked around a mooring by placing a loop over a dowel or hook in the locker, and locking the locker.

Dinghies as lifeboats

Dinghies are sometimes planned to be expedient lifeboats. Lifeboats should have enough fixed-displacement (i.e. foam) buoyancy to be unsinkable. They also should have a boarding ladder. It is very hard to enter most boats from the water. A lifeboat should also have space for the crew to lie down and enough room for emergency equipment.

A lifeboat should include an emergency position indicating rescue beacon, a parasail-type sea-anchor, signaling equipment, medical supplies, food, clothing, shelter and water for at least three days. It's reassuring to have a solar still to obtain more water, and fishing lures and line for food. Include a manual on lifeboat survival.

Some persons plan to rescue themselves. They place a collapsible sailing rig and simple navigational equipment (a plastic sextant, a compass, a calibrated quartz watch and a nautical almanac) in the dinghy. The rig should include a mainsail that can be reefed for storms, and a sea-anchor. The sailing rig also allows self-rescue if the engine quits and one grows tired, as can happen if one is swept out to sea. Kite-surfing kites may be a compact substitute for a sail and mast.

A lifeboat must have a cover. It should be able to keep out rain, make shade, and open on a choice of sides for ventilation.

The cover and sail should be colors visible from the air against the ocean.

The cover and/or sail should both be able to capture rainwater to a container. The usual scheme is a fabric channel on the bottom edge, held open with small balls of foam plastic. Many groups' lives have been saved by collected rainwater.

The extra equipment can be stored in a bag that's tied to and kept under the dinghy at sea, and brought into the cabin in port.