Nautical Terminology

Herein, we endeavour to explain some of the nautical terms used in the blog. If readers are still uncertain of any meaning, please raise a comment through the website and we will try to help!

ºM A ‘magnetic’ bearing as displayed on a compass which is not the same as a ‘true’ bearing (ºT) as drawn on a chart. Magnetic north differs from true north by ‘the magnetic variation’ which is currently 5ºW.
ºT A ‘true’ bearing as drawn on a chart which is not the same as a ‘magnetic’ bearing (ºM) as displayed on a compass. Magnetic north differs from true north by ‘the magnetic variation’ which is currently 5ºW.
Batten Battens are long, thin strips (usually fiberglass or some similar material nowadays, but historically wooden) used to support the roach of a sail.
Cringle A small hole anywhere along the edge or in the corner of a sail. Typically it encloses a metal grommet for reinforcement and to reduce wear. Reefing lines are passed though cringles in the trailing edge of the mainsail.
Freeboard The “walls” of the hull which run from the waterline to the gunwhales. A high freeboard tends to prevent crew members falling out of the boat and therefore, in most cases, is to be encouraged.
Gameboy SWMT (and general sailing) slang for the electronic chart plotter which is very similar to the satnav found in modern automobiles.
Goose-Winging Normally, the headsail and mainsail are hoisted on the same side of the mast. This produces the best laminar flow. In light airs, when the wind is directly behind the boat, the headsail will be on the port side and the mainsail on the starboard side in order to make best use of whatever wind there is.
Lazyjacks Lazy jacks (or lazyjacks) are a type of rigging which is used to assist in sail handling during reefing and furling. They consist of a network of thin ropes which is rigged to a point on the mast and to a series of points on either side of the boom; these lines form a cradle which helps to guide the sail onto the boom when it is lowered, reducing the crew needed to secure the sail.
Leading Lights Leading lights are a pair of light beacons, used in navigation to indicate a safe passage for vessels entering a shallow or dangerous channel. The beacons consist of two lights that are separated in distance and elevation, so that when they are aligned, with one above the other, they provide a bearing.
Reef Reefing is a sailing manoeuvre intended to reduce the area of a sail which can improve the ship’s stability and reduce the risk of capsizing, broaching, or damaging sails or other equipment in a strong wind. Reefing is achieved by pulling on reefing lines which are attached to cringles in the mainsail; this has the effect of reducing the size of the sail and thus its wind resistance. The basic rule is to reef as soon as you wonder if you ought to. In any case, a boat should be reefed if the wind is likely to cause it to heel beyond 25 degrees.
Reefing Lines These lead from the cringes on the sail through rollers inside the boom to the mast foot and then back to the cockpit.
Roach The shape of a sail is seldom a perfect triangle. It is common for sailmakers to add an arc of extra material on the leech, outside a line drawn from the head to the clew. This additional part of the sail is known as the roach; mainsails usually have roaches, but they are very occasionally found on specialized jibs as well. They provide additional power for a given mast/boom size
Sail Batten See Batten
Tacking Tacking or coming about is a sailing manoeuvre by which a sailing vessel (which is sailing approximately into the wind) turns its bow through the wind so that the direction from which the wind blows changes from one side to the other. For example, if a vessel is sailing on a starboard tack with the wind blowing from the right side and tacks, it will end up on port tack with the wind blowing from the left side.This manoeuvre is frequently used when the desired direction is (nearly) directly into the wind.In practice, the sails are set at an angle of 45° to the wind for conventional sailing ships and the tacking course is kept as short as possible before a new tack is set in. A similar manoeuvre (termed gybing) is used when sailing before the wind.

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