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Don't know a sampan from a sampson post? Perplexed by parrels, pelorus or pirogues? Harrassed by a harmattan? Welcome to the PBO glossary containing over 1,500 words, from simple sea terms to archaic sayings and ancient nautical nomenclature.

A-Bracket

A metal bracket which supports a propeller shaft beneath the hull, just ahead of the propeller.In form it is more like a V than an inverted A. A single-legged bracket doing the same job is called a P-bracket, and looks more like this b.

A-Lee

On the opposite side to that from which the wind is coming. The helm is a-lee when it is put down to Leeward. When put to Windward it is put Up because the heeling of the boat makes one side up, t' other down. A-lee is not often used, and though one might say, "That's Fred's boat a-lee, isn't it?, most people use 'To leeward' instead. (And leeward is pronounced loo-erd.)

Aback

A sail is aback when it is sheeted towards the windward side of the boat. A headsail is sheeted aback when a boat is Hove-to, so that the wind pressure on it counterbalances the forward pressure on the mainsail and the boat is brought nearly to rest. A headsail may also be held aback in order to help blow the head of the boat round on to a fresh Tack. In a small boat, such as a dinghy or day-sailer, the mainsail can be pushed aback (or Backed) so that the wind pressure is on the forward surface of the sail and the boat is thrust sternward.

Abaft

Behind. A position abaft the mast is behind the mast - nearer the stern. The opposite used to be afore, but many people would nowadays think Afore affected, and would prefer to say Forward of the mast, or Forward if that comes more naturally. In references to navigation lights, collisions and other important occasions the word is commonly used in the phrase 'Abaft the beam'. That defines the area from half-way along the vessel to right astern. It is as iflooking over one's shoulder. The mid-point in this sector, on each side, is the vessel's Quarter, though it is common to refer to the whole sector as the quarter. Thus one may say, 'There's a ship coming up on our starboard quarter...' And if things continue to extremes, your lawyer may subsequently write, 'and she struck my client's vessel abaft the beam .. .'

Abeam

A position at a right angle to the fore and aft line of the vessel, and not on the ship herself. A lighthouse, for example, comes abeam when it is at a right angle to the centre line of the boat. For navigational purposes the right angle is important - a landmark may seem to be abeam over quite a wide arc. To make sure, it is best to compare the compass bearing of the object with the heading of the boat.. Alternatively it may be possible to sight along some part of the boat herself (such as a bulkhead) in order to establish the correct line. (And see Athwart.)

About

To go about is to Tack the vessel through the wind. That is, to turn a sailing boat towards the wind, till the wind is dead ahead and to continue until the wind is on her other side. That done, she is about. When it is to be done the preparatory command, 'Ready about' can be given so the crew (if any) knows what to expect. This is followed by 'Lee-oh' as the helm is put down to leeward to start turning the boat.

ABS

The common name of the plastics material acrylo-butadene-styrene, which can be moulded without reinforcement to make small craft such as dinghies or' canoes.

Accelerator

An additive to polyester resin to speed its cure at normal tempera¬ture. Otherwise the resin could be cured by heating from an external source. Many resins are supplied with the accelerator ready-mixed, but if it is separate, care must be taken not to mix the accelerator and the Catalyst together as an explosive reaction may result. (Please see Polyester resin.)

Accommodation

The habitable part of a boat. But the accommodation ladder is not the ladder leading to it ! The Accommodation ladder is over the ship's side and brings you on board from a dinghy. (And see Companion way.)

Admiralty Warrant

The authority by which members of some British yacht clubs may fly the Blue Ensign instead of the Red. Permission is granted to an individual upon application, and the blue may be flown from his vessel only when he is aboard or in effective command. If you are interested in this sort of thing get full details from your club - though you may have to join another if yours is not one of the elect...

Adrift

As in ordinary language, something that is drifting on the water, such as a boat whose mooring has broken. But also used of fixtures or fittings which have become unfixed or unfitted, as in 'The tiller's adrift' which is another way of saying 'It came to pieces in me 'and'.

Aground

When the boat is resting on the bottom in a place where she would otherwise be afloat. Resting on the grass in the boatyard she is Ashore and she would also be ashore if driven high up on the beach by the wind and tide to a position where should would not naturally be re-floated. When a boat is deliberately put aground she is Grounded. She may 'take the ground' regularly on a drying mooring, and in that case you would say 'She's aground', when her weight begins to be supported on the bottom, and 'She's dried out' when all the water has receded.

Ahead

Ahead. (And the same may be said of up, down, afternoon, and supper time. Let's not bother any more with obvious words.)

Ahull

Lying to the wind with no sail set. A heavy-weather tactic, adopted only when the wind is so strong that no canvas will stand and heaving-to becomes im¬practicable. (Or when all the canvas is blown to tatters anyway.) In severe gales or storms the Windage of the spars and rigging will press the boat over and steady her. She may lie broadside or, with helm lashed down, may sail 'Under bare poles' with the wind on her Quarter.

Airtank

Just what it says - a hollow box or tank, made of wood, metal or other, containing nothing but air and completely watertight. Some lifeboats have a great many such tanks, carefully shaped so as to pack into any available space, providing a reserve of buoyancy. The use of many separate tanks means that even if the hull is holed only one or two local tanks might be damaged, with little loss of buoyancy.

Aldis lamp

A signalling lamp. Its beam is very narrow and concentrated, and thus visible at a great range - so long as it is aimed correctly. The pencil-wide beam is aimed by a telescopic sight on the top of the lamp.

All Fours

A vessel is moored all fours when she is held by four lines, two from the Bows and two from the Quarters, as she would be in a mud-berth, for example.

All standing

With all sail set. To 'Gybe all standing' is to gybe without taking any precautions to relieve the shock - just slam-bang. To 'Turn in all standing' is to sleep in your clothes, perhaps before an early start, perhaps because you expect to be up and down during the night, or because you've forgotten your pyjamas.

Almanac

An annual tabulation of astronomical information, especially as required for celestial navigation. There are a variety of almanacs for various purposes, ranging from Old Moore's to the Air Almanac which is intended for aeronautical navigation. For boat-owners and skippers Reed's or The Silk Cut are the primary references, though oddly enough most of us are less concerned with the almanacal information than with its other content. In fact both contain much more than the astronomical ephemera, since they are packed with advice on seamanship, first aid, radio communications, and so forth. They also list lights, buoys and other marks. I cannot mention all the content here, but I am of the opinion that every sea-going boat should have a copy of one on board. Even an out-of-date copy of either has much practical value. Practical Boat Owner's cruising almanac is simplified, inexpensive, and benefits from monthly up-dating in the magazine itself.

Aloft

A position somewhere above the deck, and usually well above. In other words well up the mast or rigging. If you are aloft in a bosun's chair, those on deck are alow, but it would be something of an affectation to use the word nowadays; Below would be more customary, even though it has the specific meaning of below decks. Aloft is also an adverb, as in 'a good sailor always looks aloft'.

Alongside

By the side of the ship, or by the side of a quay or dock. Your dinghy may be alongside your boat, or you may put your boat alongside a quay. When berthing next to another boat one normally asks 'May we come alongside?', if there is anybody to ask.

Alpha

As a single letter in the International Code of Signals the letter A means, 'I have a diver down; keep well clear at low speed'. It is a signal which should be flown by any boat tending divers, and one which should be heeded by all passing skippers. Like most other single-letter signals, this one may be made by light, sound or any other means. In speech the word to use is Alpha. In Morse code the letter A is • -. When Morse code was widespread, a series of As was transmitted by a station to attract attention to the message which is to follow.

Alternating (light)

A navigational beacon or mark whose light shows changing or alternating colours

Amidships

The centre part of a vessel. Can refer to the point midway between fore-and-aft or athwartships, ie halfway between the port and starboard sides.

AMRINA

Associate Member of the Royal Institute of Naval Architects.

Anabatic Wind

A localised wind that flows upwards. Generally occurs in mountainous areas. It's the opposite of a katabatic wind, which flows downwards, generally from a cliff.

Anchor

There are various types of anchor, which hold a boat to the seabed. Weight for weight, the Bruce, the CQR and the Danforth have by far the best holding power. The principal anchor of a boat, dropped from the bows, is called the Bower anchor. The Kedge is a lighter, subsidiary anchor, used for a lunchtime stop or taken out in the dinghy to haul off when you have run aground. This is then called Kedging, or Kedging off.

Anchor buoy

A buoy supporting the Anchor Tripping Line, see below

Anchor Light

An all-round white light which must be shown by any vessel lying at anchor between the hours of sunset and sunrise. Normally in the fore-part of the vessel, though you may show two such lights (Rule 30).

Anchor tripping line

A line made fast to the Crown of the anchor, and supported in the water by a buoy at its upper end. The line may be used to unhook the anchor and pull it out head-first if it gets foul of a rock or an old mooring cable on the bottom. Many skippers think the cure is worse than the disease, involving the chance that the line will get foul of a passing boat's propeller - or even your own.

Anchor Weight

See Angel.

Anemometer

An instrument for measuring wind-speed.

Angel

Sometimes known as an Anchor Weight, An angel is a weight lowered on a line down a yacht's anchor cable to increase the catenary of the cable, which improves holding and reduces snubbing in strong winds. It also keeps the anchor line clear of the yacht's keel, helping in situations when opposing wind and tide might otherwise cause major tangles.

Angle of incidence

The angle at which air flow meets a sail, or water flow meets a keel or rudder. The term is general to physics, and relates to the angle at which light falls on a mirror, or at which radio waves meet a radar reflector. In aerodynamics, the expression "angle of attack" is sometimes used with the same meaning, notably in the US of A.

Anode, Sacrificial

Please see Galvanic corrosion.

Answer

The response of a boat to her helm. "She doesn't answer' is the anguished cry of the helmsman whose rudder has dropped off or whose boat is aground

Anti-fouling net

Used to prevent spinnaker foul-ups, it takes the form of a series of light ropes or tapes arranged in the form of an open network with very large mesh. It is hauled up the forestay and fills the gap between forestay and mast like a sort of skeletal staysail, and so prevents the spinnaker from passing behind the forestay. To appreciate the need for an anti-fouling net (or Lazy jacks) you really need to see the horrid sight of a spinnaker which has wound itself tightly round a forestay, defying all attempts to clear it or lower it.

Anti-fouling paint

A paint for the under-water parts of a hull, formulated to prevent the growth of living organisms such as weed or barnacles. The paint contains poisons of various kinds - such as compounds of copper, tin, arsenic or the like - and these compounds leach out slowly to the surface. At the surface they should kill any microscopic young forms of life before they can gain a foothold. Fouling growths do not feed off the material of the hull, they merely use it for an anchorage, and if they are not killed before they hitch on, they quickly grow big enough to draw their nourishment from water well clear of the poison at the paint surface. Scrubbing will remove young growth and may release extra supplies of poison to hold new invaders at bay. For practical purposes it is important to know that there are two types of anti-fouling paint - those that must be immersed in water within a few hours of application (Soft), and those which may be applied and left for a matter of weeks before launching (Hard).

Anticyclone

High pressure area enclosed by widely spaced isobars. In the central part, where pressure is highest, wind speeds are low, skies are clear or slightly cloudy, and precipitation is rare. Winds blow outwards from the centre - clockwise in the Northern Hemisphere, but anticlockwise in the southern hemisphere.

Apparent wind

The wind direction and strength as measured from the boat herself. This is a compound of the natural, or True wind and the wind due to the boat's own movement over the face of the earth. The boat's movement is the sum of her movement through the water and the movement of the water over the bottom. In a flat calm, a boat moving forward with the tide or under engine has an apparent head-wind. If a natural beam wind then springs up it will appear to 'draw ahead' of its true direction by reason of the boat's self-made head-wind.

Appendage

An underwater surface which protrudes from a hull. That's to say any sort of keel, rudder, or skeg.

Apron

A timber in the form of a broad, thick plank which is fitted immediately abaft the stem to form landings for the plank ends. More recently it has come to be used for the raked forward face of a catamaran's bridge-deck. It is also a thing worn by the galley slave to keep splashes off her clothes, and by the leadsman when taking soundings by lead-line, which is very wet work.

Archboard

Please see Transom.

Arming

Tallow or other stiff grease which is pressed into the saucer-like depression at the bottom of a sounding Lead. Its purpose is to pick up a sample of the bottom as an indication of position. The nature of the bottom is marked on charts with abbreviations such as, S sand, M mud, Sh shells, R rock, and Co coral (though most of us will be well off course if we come across the last-named). See Admiralty Chart 5011, now in booklet form, for full details of chart symbols and abbreviations.

Armstrong's patent

Jocular term for a windlass or the like, whose power source is the strong arms of the crew.

Asleep

A sail is asleep when it has no wind in it and, though set, is doing no work. It may be asleep as the boat goes about, in the interval between drawing on one tack and drawing on the next. This is a good moment to shorten the sheet, while there is no load to pull.

Aspect Ratio

The aspect ratio of a sail is its length in relation to its breadth, or its height in relation to its fore and aft dimension. A tall, narrow Bermudan sail has a high aspect ratio, a gaff sail has a low AR. A high-aspect-ratio sail shows greatest efficiency when on the wind (Le. close-hauled) but a low-AR sail is better off the wind, when running free (as in the Trade Winds). The actual numerical value of AR is found by dividing the length of the luff by the mean chord - that's to say, the fore and aft dimension half-way up the triangle. If the latter dimension is not easily found, you may find it more convenient to square the luff length and divide by the sail area. The simplest answer of all is to divide the luff length by half the length of the foot of the sail- the result will be accurate enough for any ordinary purpose.

Astern

A position somewhere aft of the boat. Motor cars reverse, but boats 'Go astern' under the power of their engines. When the engine is no longer actually pulling her astern and she is moving under her own momentum she is said to be 'Carrying stern way'. Likewise she would be 'Making stern way' if nudged back¬ward by the wind. (Some people claim that a ship is 'under weigh' when moving ahead, but they don't use 'Weigh' when she's going astern. Draw your own conclu¬sions.)

Astro

Short for astro-navigation, which itself is short for Celestial navigation

Athwart

Across in ordinary language. Athwartships means across the boat herself, as opposed to fore and aft. Note that the seat running across a dinghy is called a Thwart.

Autopilot

Automatic steering gear, which can take two principal forms, those which are wind-powered and those which are battery-powered. The wind-powered steer in relation to the wind direction, and therefore the boat's track changes when the wind shifts. Electric autopilots normally steer a compass course, which is preferable for nearly all purposes, but when a boat is under sail there is a drain on the batteries.

Aweigh

An object is aweigh when it is hanging by a rope or chain. Normally the term is used only of the anchor, which becomes aweigh when it is hanging free, either ready to drop, or ready to lift because it has just broken out of the ground. Lifting a dinghy from the deck with tackle you could say 'Dinghy's aweigh' as soon as she is lifted clear, but the risk of confusion with 'away' is only too obvious. I don't think many people even say 'Anchor's aweigh' in real life: they are more likely to shout 'It's free', or something equally meaningful and understandable.

Azimuth

The azimuth of a heavenly body is its bearing in relation to True North, as observed by you. The use of the word in this way is navigators' jargon, and as such is correct. The azimuth of the body concerned is properly speaking an arc extending from a point vertically above your head (the Zenith) and running down to cut the horizon - like a big slice through the celestial globe. The bearing is measured between True North and the point where the azimuth cuts the horizon, hence the abbreviation azimuth as used in everyday seamen's parlance.

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