1) The single-letter signal means, ‘Keep clear of me, I am engaged in pair trawling’. This is an important signal for pleasure-craft skippers, and since the signal flag consists of red, white and blue in three vertical bands you might mistake it for the French ensign. The Morse code is one dash, but the above signal cannot be made by a single hoot because that means, ‘I am altering my course to starboard’. Tango is the word for T in phonetic.

T (2) True. See also: North.

Used at the end of rigging wires to secure the wire to the mast.

Servo-tab: A small surface which, when acted upon by the water flow, moves a larger surface (e.g. the main rudder) by means of leverage.

Tab (2) The fixed end of a piston hank

A metal or wooden structure, in the shape of an open box, which locates and supports a deck-stepped mast. A bolt passing through tabernacle and mast can provide a pivot point for lowering the stick. Although the tabernacle supports the downward thrust of the mast it should not suffer any of the wrenching or side loads, which are taken by Shrouds and Stays. (See also: Lutchet)

Those parts of a sail which are reinforced by doubling or trebling the thickness of the material and over sewing.

An instrument for measuring the rate of revolution of the engine.

1) The lower, forward corner of a sail. May be hauled down tight by a Tack-line or a Tack tackle. (See also: Clew and Head) Tack (2) A turn of the bow through the wind while sailing

When sailing close-hauled, to turn the boat’s head through the wind so that the sails draw on the opposite side. When sailing with the wind coming from port, the boat is ‘on the port tack’, and she is ‘on starboard’ when the wind comes from her starboard side. To make progress to windward by sailing fIrst on one tack and then on the other is ‘tacking’ or ‘Beating to windward’. Although tacking usually implies close-hauled sailing, it is sometimes desirable to ‘tack down wind’, turning slightly off the wind fIrst to one side and then to the other. That may be faster than running directly down wind, and it may avert the risk of an accidental gybe. (See also: Wear, to.)

An assembly of one or more blocks with one or more ropes to achieve a mechanical advantage. There is a variety of names for their many forms – the Spanish burton, the single whip, the gun tackle and the lufftackle, for example. Sadly, they are little used on modern craft and are to be seen mainly in mainsheets, kicking straps and tack downhauls.

The rail around the stern of a boat which may save you from falling overboard. Modern yachts do not have the elegant wooden rails of their forebears, but have tubular metal railings instead, called Pushpits.

The act of pulling on a rope that is round a winch.

To pass a rope around a post or bollard. (See also: Snatch, to)

A boat takes the ground when the tide recedes and leaves her there. This is a gentler process than running aground which almost always implies an error, whereas taking the ground suggest that it was the skipper’s intention – or at least his expectation.

A planked wooden boat may become so dry ashore that the planks shrink and allow water to leak between when she is put afloat. But as the wood swells she will ‘take up’, which simply means that her seams will close up.

A patent form of Swaged splice for wire rope. Also the machine which enables you to tailor it …

A metal strip, bolted or riveted to a spar, to provide an attachment point for shrouds, stays and the like.

One that marks the position of a submarine cable. The point where a cable reaches the shore is marked by a ‘telegraph cable landing beacon’ which can be identified by its diamond-shaped, red and white topmark.

Two kinds. One is the compass which the skipper mounts over his berth so that he can check what you are doing at the helm even when you think he is asleep. The other is a short length of cotton or tuft of wool which is attached to sail or shrouds to show the direction and steadiness of the air flow.

1) Any small boat used to take people or stores out to a bigger one. Your inflatable dinghy, for example. Tender (2) An adjective that describes a boat that heels rather easily. It refers to a boat’s initial Stability, rather than the ultimate.

The ‘shipworm’, is a mollusc that looks like a worm. At microscopic size it penetrates underwater timber and there spends the rest of its life, eating your boat away. Remaining within the thickness of the planking it can grow to a foot or more in length and as fat as your finger. The galleries made by teredo will destroy the structure of a wooden ship. But they do not abound in temperate waters. They can be held at bay by a sound coat of Anti-fouling paint, or by copper sheathing, and they die if the boat is removed from salt water for a fortnight or more.

The fittings that form eyes or attachments in the ends of wire ropes. There is the swaged, or Talurit type of eye, and there are patent devices with screw-together bodies which clamp the end of the wire in some way.

When an owner talks about his ‘five tonner’ he refers to a peculiar type of tonnage which has nothing to do with weight. More than a hundred years ago the Royal Thames Yacht Club adopted a formula for estimating the tonnage of yachts, and we still can’t break free of it. The formula takes no account of weight, but relates entirely to length and beam. The measurements are taken in feet. Because beam acts twice as a multiplier, fat boats have disproportionately large tonnages. (See also: Displacement and Register tonnage.)

A wind caused by differential heating, usually of sea and land. For example the sun heats the land more rapidly than the sea, the air rises over the land and a Sea breeze flows towards the shore to replace it. By night the land cools more quickly than the sea, and the result may be a Land breeze in the opposite direction.

A metal or plastic eye that fits inside an eye formed in rope or wire rope to prevent chafe. A thimble may be round or pear-shaped.

Thixotropic paints and resins are those which do not easily run when applied to a vertical surface, though they are quite easily brushed out or spread.

Wooden pegs or dowels shipped vertically in pairs in the gunwale so as to constrain an oar for rowing. Most people now use Rowlocks.

l) The space in a block where the rope passes through, but Swallow is the preferred term. Throat (2) The upper forward corner of a gaff sail.

A small cleat with only one horn. To some people it looks like half a cleat.

An ordinary pretzel knot joining two rope ends not under load

The thwartships plank which forms a seat in an open boat. There may be several such, depending on the size of the boat, and in addition to their role as seats they may also be essential components of the boat’s structure. Some dinghies also have seats to port and starboard called side benches.

A hydrographic booklet which shows the direction and speed of the tidal streams around the coast for each hour of the Flood and Ebb. There is a tidal atlas for each section of coast – see the Catalogue of Admiralty Charts.

The rise and fall of the water level in the great oceans naturally causes a flow out of or into narrower seas, such as the English channel, though some (like the Mediterranean) are so narrow and shallow at their entrances that the effect is very limited. The flow of a rising tide is called the Flood, and that of a falling tide is called the Ebb. If the tide starts to come in, one may say that it is ‘Making’, though the same term is used for the period of days between Neaps and Springs when tidal heights are growing greater. During the reverse process, after springs, tides are said to be ‘Taking off’. Tidal streams are important to small craft because they commonly attain speeds of two or three knots, and in a four or five¬knot boat there is a world of difference between two knots against you and two knots with you. Apart from its influence on one’s speed of progress, the direction of the tidal stream is important in relation to the wind: ‘wind against tide’ tends to kick up a rough sea. (See also: Tidal atlas, and Height of tide.)

The combined gravitational pulls of the sun and the moon draw up the earth’s ocean into a hump, called a tidal wave. This wave moves across the water as the earth rotates, and though it is only a low lump (unnoticed by seafarers), its effect when it reaches the shallower waters near land is to create the to and fro surges which we call Tides. It may be worth mentioning that the expression ‘tidal wave’ is commonly misused for a phenomenon which should be called a ‘Tsunami’.

Tides are one of the most important factors to be taken into account by the coasting skipper. It is the rise and fall of the level of the sea at regular intervals, corresponding to the phases of the moon. That is so because the moon’s phases are an indication of her position in relation to the sun, and it is the combined gravitational attraction of those two bodies which raise the sea. The moon’s monthly (28-day) cycle gives the tides a fortnightly cycle, the tides being greatest when the sun and moon are either on opposite sides of the earth or on the same side, and least when they are at a right angle. The greatest tidal Ranges are called Spring tides, and arise at the new and full moon; the least are called Neaps and occur at the quarters. The fortnightly cycle of tides is rather convenient to live with: if High tide is around midday this week-end then it will be around midday in a fortnight’s time, but at morning and evening next week. The times of High and Low tides for each day of the year are shown in Tide tables, often free from chandler’s shops, but also in Almanacs and suchlike, Also shown are the Heights. (Please see also Tidal stream.)

Usually takes the form of a post standing up in the water and marked in metres. It shows the current height of the water surface above chart datum, that is to say the depth which is at that time additional to soundings shown on your chart. To be absolutely correct, it shows the height of the tide. Be aware though, that it does not show directly the local depth of water; that is the function of the Depth gauge.

A stretch of water where a fast-flowing Tidal stream creates turbulence, usually because the bottom shallows.

A boat lying at anchor is said to be tide-rode when her hull is laying primarily in the direction of the Tidal stream. Alternatively she may be Wind-rode.

Short for watertight. Used of a good hull which does not make water.

The lever or handle by which the rudder is turned. In some dinghies a tiller extension may be necessary for the helmsman who sits so far outboard that he cannot reach the tiller itself. In big heavy boats tiller lines rigged with tackles may be needed to augment the muscular power of the helmsman. Tiller lines without tackles may also be used to fix the helm in a chosen position.

The ribs of a hull are called Frames and timbers. Timbers are usually bent to shape, after steaming, while the heavier frames are usually sawn to shape or laminated.

A patch applied to a hull to stop a leak. Commonly a copper sheet nailed down over a piece of cloth which has been well coated with tallow, but the exact ingredients are likely to be a matter of improvisation.

The bottom of a keel or rudder.

Thames Measure (tonnage)

Lengths of webbing running fore and aft in a racing dinghy, and arranged so that the crew can hook their feet under them when sitting the boat out. (And see Hiking straps)

An elongated wooden button. Found on the hoist of a signal flag or the front fastening of a duffle coat.

The various kinds of tonnage are a great source of confusion. As far as private owners are concerned the three kinds that may matter are Displacement, Thames measurement, and Register tonnage. The matter is further confused, though by the racing classes who compete for Quarter, Half and One Ton Cups in craft whose design is closely controlled by lengthy and complex rating formulae which have nothing to do with tonnage in its ordinary sense.

All the structure above the hull, notably deck-house, Dog-house, companion, rails, radar scanner and so forth. All such creates windage, tends against stability and generally hampers the boat in her efforts to cope with wind and sea.

The true topmast, in the form of a separate spar which could be ‘sent up’ to extend the height of the lower mast, and struck and ‘Housed’ on the foreside of the lower when its weight and windage aloft would be an encumbrance, is now rare. There are still a good many gaffers around with longish pole masts, approximating to the total length of former mast-plus-topmast assemblies, and the upper part of such a long mast may by convention be called the ‘topmast’.

A rope from the mast to the boom end which supports the boom and allows you to lift or lower it. (See also: Lift)

On a Gaff-rigged boat the topsail sets above the mainsail and fills the triangle between gaff, mast and sky. It may do more if set on a Topsail-yard, a pole which extends higher than the mast and to which the luff of the topsail is laced. (See Jackyard.)

The sides of the hull between the waterline and the deck.

A small open Cornish fishing boat noted for her good carrying capacity resulting from plenty of free board and firm bilges.

1) The locus of the ship’s progress over the face of the earth – the actual line along which she travels. See also: Course

Track (2) A channel or ridge, running from top to bottom on the after side of the mast, and in or on which the Slides on the luff of the sail can slide.

See Head up.

Carved decorative boards fitted to port and starboard of a hull, at Bows and Quarters (or both). Although a word not much used in day-to-day life, a trail is any design or pattern based upon trailing, intertwining tendrils, curlicues and the like. (See also: Quarter badge)

A plank bearing rear lights, flashing indicators and the registration number of the towing vehicle, which is fitted to a dinghy being trailed on the road.

The after edge of a sail, a keel or a rudder – or any other surface subject to fluid flow. Specifically used in relation to aerodynamics and hydrodynamics. Note that the trailing edge of a sail is at the Leech, while the leading edge is at the Luff.

A sea wall or embankment built for the purpose of directing the current or stream in the required direction. For example at a river mouth where the water would naturally slow down and deposit silt, a training wall will constrain the water to move faster, and so carry its silt out towards the deep.

A net of rope or webbing filling the gap between the two hulls of a catamaran, usually forward.

An electronic sensor relaying data to instruments, eg depth, wind or speed.

A fix is usually taken by crossing two Position lines observed within a few minutes of each other. But where a significant time must elapse between the observing of the two position lines, the first must be translated along the ship’s track by the distance that she has travelled in the interval.

A transit is taken by sighting two objects in line. If the objects can be located on the chart, the observer is obviously somewhere on an extension of the line passing through them, and such knowledge is invaluable in pilotage. Furthermore, if the bearing of such a transit is observed with the compass, the reading can be compared with the magnetic bearing derived from the chart and any compass deviation can be deduced. A practical navigator will always be on the look-out for pairs of objects which provide good transits, and will frequently use them to check his compass.

In housebuilding and shipbuilding a transom may be simply a crossbeam, but in small craft the word refers specifically to the transverse after end of the hull, including any stiffening beams or structure. A hull may have a pointed stern, a cut-off transom stern, or an up-sloping and overhanging Counter which itself may end in a miniature ‘transom’ to which the name ‘archboard’ is properly given.

Rather like a cat flap, a transom flap opens to allow water to escape from inside a planing dinghy.

Used in sailing dinghies, a trapeze is a length of wire attached to the mast near the head and ending in a sling-seat in which the devoted crew can support herself with legs braced against the gunwale, and with all weight out to windward.

A fitting which attaches a sheet to a Horse. most commonly used to move the cockpit end of the main sheet tackle more to the windward or the leeward side of the boat. For another example, an iron ring which slides along a bowsprit so that you can attach the tack of the jib from the foredeck and then haul it outboard. A third example is a ring which travels up the mast of a lugger. The halyard is made fast to the ring and the yard of the lugsail is hooked beneath.

Tables that show the course and distance from point A, where you are, to point B, where you want to go. Points A & B are expressed in degrees of latitude and longitude. Alternatively, if you know where you started and how far and on what heading you have travelled, the tables will reveal where you are now. On the whole it’s easier, more reliable and more satisfying to draw a line on your chart.

See also: Trunnel

A fore-and-aft stay running between the heads of two masts.

Or to ‘truss up’, can be used in much the same way as a farmwife talks of trussing up a chicken. You can trice up almost anything with cord or rope, but in practice this old term lives on mainly in gaff-rigged boats which have loose-footed mainsails. Such craft will have a tricing line attached to the Tack of the sail, running through a block at the Gaff jaws, and down to the deck. The tack of the sail can thus be hauled up to reduce the sail area and spoil its shape so that the boat moves slowly. The sail is then half-way to being Scandalised.

A period of duty at the helm or on watch. To ‘take a trick at the helm’ is more nautical (and possibly schoolboy humorous) than ‘steering for a bit’.

A lamp showing red in the proper port sector, green in the starboard sector, and white astern. The International Regulations for Preventing Collisions at Sea, 1972, permit sailing boats of less than 12 metres length to carry such a ‘combined lantern’ at the masthead.

A small underwater plate fitted at the stern of a motor boat to act like the elevator of an aeroplane. Often mounted in pairs, trim tabs are usually required to lift the stern and so make the hull trim to a running angle which causes least drag in the water. Some trim tabs are at a fixed angle, others can be controlled by the helmsman.

1) To adjust the set of the sails to best advantage.

Trim, to (2) To adjust the sit of a boat in the water to the best advantage, usually so that she floats parallel to the designed waterline, though there may be times when it is desired to trim a boat by the head (bow down) or by the stern (bows up) for some special purpose. In a rowing boat, the request ‘trim the boat’ requires the passengers to shift their weight so that the boat will be level. The verb may also be intransitive, as they say at school, for the boat herself may be observed to ‘trim by the head’, for example.

Although this word has been formed from catamaran, it is misleading if it suggests that because a catamaran is a two-hulled boat a trimaran is three-hulled. The trimaran, like the Proa, has a single hull which is too narrow to be stable without the assistance of a Sponson or an Outrigger. But whereas the proa has only one sponson, a trimaran has two. In most tris, only the leeward sponson is in contact with the water, the other being lifted clear by the slight heel of the boat.

The General Lighthouse Authority (GLA) for England, Wales, the Channel Islands and Gibraltar responsible for aids to navigation.

A line attached to the Crown of an anchor and leading up to the deck so that the anchor can be broken out of the ground. The tripping line may be seized to the Shank of the anchor by a flimsy bit of line to avoid accidental tripping, while a strong pull for intentional tripping will break the line and so apply the pull to the crown end of the anchor. A tripping line may lead to the deck, or to a free floating anchor buoy. In the latter case a few feet of rope immediately beneath the buoy should be weighted so that it will hang straight down, clear of the propeller or rudder of any passing craft. If you have a fair idea of the relevant depths, a simple scheme is to use a shorter tripping line, with its upper end seized to the anchor cable itself. The line should be short, but long enough to be above the water and at hand when the cable is hove short.

A circular wooden capping piece for the top of the mast. It keeps water from entering the end-grain, and its overhanging rim offers a suitable place for the fitting of a burgee-halyard sheave. Also an obsolescent name for a Parrel bead.

The wind with the direction and velocity as measured by a stationary observer (e.g. on an anchored vessel). By contrast, the Apparent wind is the wind observed from a moving vessel.

A vertical passage open at top and bottom, such as the housing in which a dagger board slides up and down, or the broader passage which allows an outboard motor to do the same . An air duct to or from an engine compartment is likewise called a trunk, but only if it is relatively short and uncomplicated. Where it is long and tortuous the idiom will be to talk of ‘trunking’.

2) The fabric or plastic tubular drain that can be raised or lowered from the transom of a RIB to let any water out of the rigid hull is often known as the elephant’s truck because the fabric is often grey in colour

A nice rounded West-country man’s way of saying treenail, which may also be pronounced as spelled, or as ‘trennle’. Anyway, it is a wooden spike or nail, used for holding planks to timbers, and so forth. As a fastening it is not likely to be used in private pleasure craft, being better fitted to craft of bigger size where the Scantlings give sufficient thickness for a trunnel to get a grip.

A small sail of heavy canvas, set on the mast in place of the mainsail and sheeted aft with powerful tackles. It is in fact a riding or steadying sail which dampens the rolling of the hull in gale or storm conditions.

Twin Screw Diesel Yacht.

A series of extremely large waves caused by submarine earthquakes. They travel for thousands of miles and cause devastation when they reach an inhabited shore. Newspapers call them ‘tidal waves’, mistakenly. If tsunami does not roll off the tongue, you can quite correctly call them seismic sea waves.

The underwater part of the stern of a hull, corresponding to the Forefoot at the other end. At the tuck the sides, bottom and transom (if any) all merge neatly together.

l) Where reef points, slab, or jiffy reefing are used, one speaks of ‘tucking in a reef or even ‘taking a tuck’. ‘It was blowing pretty hard, and we had a couple of tucks in’, is the well-sounding way of saying that the first and second reefs had been made. Properly speaking, a reef is that actual area of canvas between two rows of reef points, and when that panel has been tucked in and tied down you have certainly ‘taken in a reef.

Tuck in, to (2) A seaman also tucks in a splice, and uses that verb where ‘make’ would be the ordinary word.

An inward slope of the upper parts of a hull or cabin side. The opposite of Flare.

An ornamental knot, used to make a stopper or handhold at a rope’s end. Looks more like a turban or Turk’s hat than his head.

A jolly expression for going to bed fully dressed and ready for all the pleasures of leaping out again at a moment’s notice.

The part of the hull where the ‘bottom’ meets the ‘side’, and there is a general curving upwards. In fact it is that very part of the hull properly called the Bilge, a word which itself derives from ‘bulge’.

The period of slack water when the tide is about to flow the other way.

Turning to windward is what most people call tacking – but with the implication that the boat tacks repeatedly and makes progress to windward. Idiomatically, there is no such thing as one ‘turn to windward’ in the way one turns a boat’s head to the wind. In short it is not the same as mere Luffing, but the process of getting to windward, first on one Board and then on the other. (See also: Beat, to.)

To turn completely upside down. Is used only of craft, whereas Capsize is used of a coil or rope, a fried egg or anything (or anyone) else.

The same thing as a Rigging Screw, though the implication is of small size.

Tractor Vaporizing Oil. In former times was fuel used by some marine engines. Now extremely rare.

A light line attached to a Sheet at some midpoint so that the lead or tension in the sheet may be adjusted more finely. The tweaker may be made of elastic cord in order to maintain a constant tension.

See: Rule of twelfths.

This is a proper term to use for those (sailing) boats which have a pair of keels, but no central keel. Bilge keels are then reserved to those craft (sail or power) which have a main central keel and a subsidiary keel on either side of it. Usage does not in fact hold to this purist distinction.

Deliberately so shaped, and not the result of straining, this type of shackle has the axis of the pin at a right angle to the plane of the bow. In most shackles they lie in the same plane.

When two blocks of a tackle meet and no further movement is possible. (See also: Chock-a-block.)

An acoustical beacon – a foghorn – operated by compressed air and emitting a medium pitched note rather similar to the Whistle of a steamer (See also: Diaphone)