Cambridge
School of Navigation John Starkie, PhD, RNR
T Tango
Do not pass ahead of me
Tabernacle, Tack, Tack purchase, Tack tackle, Tackle, Taffrail, Tallow, Tar, Tarp, Tarpaulin, Telescope, Tell-tale, Temperature, Tender, Tether, TEV, Thames tonnage, Thole pins, Throat, Thwart, Tidal height, Tidal stream, Tide, Tide gauge, Tiller, Timber, Time, Tingle, Toerail, Toe the line, Tompion, Tonnage, Top, Topgallant, Tophamper, Topmast, Topping lift, Topsail, Topsides, Touch and go, Tow, Towing, Tradewinds, Traffic separation scheme, Trailer, Trailer-sailer, Transceiver, Transit, Transom, Traveller, Trawler, Treenail, Trestle trees, Triangle, Triatic, Trice, Trick, Tricolour, Trim, Trimaran, Tripping line, Trireme, Trot, Truck, True bearing, True North, Trysail, TSS, Tug, Tumblehome, Turn, Turnbuckle, Tye
Tabernacle
A mast-step on deck or on the keel, in which the mast works on a pivot, and so can easily be lowered.
The mast of the half-tonner to the right pivots in a tabernacle. The cover in the foredeck between the skipper's feet can be removed; the mast pivots aft, the heel of the mast pivots forward and upward through the space left by removing the cover. A lead weight is attached to the heel of the mast as a counterbalance and contributes to the ballast of the boat.
Tack
n The foremost lower corner of the sail.
n A sailing boat is on port tack when the wind is on its port side; it is on the starboard tack when the wind is on its starboard side. This is (was) because on a square-rigged vessel the tack of the course sail would be pulled hard down (tacked down) to the port bow when the wind was on the port side of the vessel.
n A small sharp nail, with a broad head, for tacking down loose carpet. Joshua Slocum scattered them around his decks when asleep at anchor so that barefoot boarding thieves would make a lot of noise.
v to change tack, eg from port tack to starboard tack, by turning toward, and through, the wind. See sheet, missed stays.
Hard tack: see biscuit.
Tack purchase
A system of lines and pulleys for applying tension to the tack of a sail.
Not a downhaul.
See Purchase.
Tack tackle
See tack purchase
Tackle
An arrangement of a line and two pulleys for increasing the effort applied.
See Purchase.
Taffrail
The rail around the stern and quarters of the boat. Derived from the Dutch word “taffereel” meaning “carved panel”.
Tallow
A rendered form of beef or mutton fat, a soft solid at room temperature but with no clear melting point.
During the Age of Sail the crew's meals were cooked (usually boiled) over the ship's galley fire: the liquid animal fat which rose to the surface was collected as slush and stored as tallow.
Tallow was used to grease the slides of the yards, to make candles and to arm the lead.
Tar
Tar is a dark brown or black viscous liquid of hydrocarbons and free carbon, obtained from coal, wood, petroleum, or peat by destructive distillation. Production and trade in pine-derived tar was once a major contributor to the economies of Northern Europe and Colonial America. Its main use was in preserving wooden sailing vessels and hemp rigging against rot. The largest user was the Royal Navy. Demand for tar declined with the advent of iron and steel ships.
Tarp
American slang for tarpaulin (sheet)
Tarpaulin
A compound noun derived, and corrupted, from two words, tar and palling: palling is material (originally canvas) used to cover items and protect them from the weather. Tarred palling (tarpaulin) was canvas impregnated with tar to make it waterproof.
In other contexts, a pall is a cloth used to cover a coffin, or a piece of linen used to cover a chalice.
Modern (21st century) tarpaulin is made from a variety of plastics.
Telescope
An optical instrument, used with only one eye, for seeing long distances. The combination of lenses makes distant objects seem nearer and bigger.
The monocular (sic) is the modern equivalent.
Tell-tale
n A light yarn (sometime redundant audio tape) attached to a shroud to 'tell the tale of the wind'.
Commercially available tell-tales have self-adhesive patches which stick to a sail close to the luff and which have a length of light yarn attached. They are sold in pairs, oftened coloured green for the starboard side of the sail and red for the port side.
Not a 'tell-tail', although the short length of coloured yarn may look like a tail.
n Someone who reveals a 'friend's' misdeeds.
Temperature
Temperature is a measure of the hotness or coldness of objects; for a given object it is proportional to the heat content of the object. Atmospheric air is sufficiently homogeneous that its temperature reflects its heat content.
Pure water freezes at a temperature of 0°Celcius, and boils at 100°Celcius. Sea water freezes at about -2°C. An object at a temperature of 50°C feels warm to the touch; at 60°C it is too warm to hold.
The temperature of the sea depends partly on the latitude (warmer at lower latitudes and colder at higher latitudes), partly on heat from the core of the earth and partly on heat exchange with the air above it.
The ocean currents move not only water from place to place but heat as well. For example, the Gulf Stream and the North Atlantic Drift move warmer water from the Caribbean to Northern Europe, so that the water around the British Isles is warmer than the water of Labrador at the same latitude in the Western Atlantic.
Air temperature is affected partly by the heat from the core of the earth, partly by exchange of heat with the sea, but largely by radiant heat from the sun. The tropics are warmer than the poles because the intensity of radiation per unit area is greater at the Equator than it is at the poles.
Warmer air is less dense than colder air, so a warmer air mass rises above a colder air mass.
Falling, colder air rotates clockwise in the Northern Hemisphere, creating gentle anticyclonic winds and stable air masses. Rising, warmer air rotates anticlockwise in the Northern Hemisphere, creating cyclonic winds up 100 knots and unstable air.
Sailors feel more comfortable at air and water temperatures between 18 and 28°C than they do at warmer or colder temperatures. Sailors who fall into water below about 10°C survive for shorter times than those who fall into warmer waters.
(The terms 'colder' and 'warmer' are relative; the Azores High is caused by falling, colder air at temperatures around 25°C. The rising, warmer air of a North Atlantic frontal system may be as low as 10°C)
Tender
adv A vessel is tender when she heels easily to the wind.
n The smaller vessel which carries crew and stores from the quay to the boat and back. A cruise ship may carry a number of tenders, which may be substantial power-driven vessels. A yacht may carry an inflatable boat, with oars or an outboard engine.
A tender tends to the parent vessel's needs.
Tether
The three point attachment strap for use with a harness or lifejacket. It has a carabiner or snap hook on each of the three ends of the strap; one attaches to the sailor's harness or life jacket, another to a strong point on the boat.
T.E.V.
Turbo electric vessel.
The main power source is a gas turbine. The turbine drives electricity generators, mainly to power the ship's domestic services and equipment. The propellers are driven by electric motors.
Thames Tonnage
A measure of the volume, or carrying capacity, of a boat, where
TT = (length - beam) x (beam x beam) / 188.
length and beam are measured in feet
It is an estimate of the cargo carrying capacity of a vessel; that is, the number of tuns of wine it can carry.
It is not an estimate of the weight, or displacement of a vessel.
See Cask.
Throat
The angle where the luff of a gaff sail meets the head.
Thwart
A cross-piece in a boat, used as a seat by the oarsmen. It is often a structural component of a small boat, helping to keep its shape.
Tidal Height
The tidal height (or height of the tide (HoT)) is the height of sea level above chart datum. See Height of tide.
Depth of water = HoT + Charted depth
The rise of tide is the distance, in metres, which the tide has risen between two chosen times, often between the previous low water and the present time, or between the present time and the next high water.
Knowing the rise of tide helps in calculating the scope of rode needed at the next high water, and in calculating when your boat will float again.
It might also tell you whether the car park will flood before you get back to your car.
The fall of tide is the distance, in metres, which the tide falls between two chosen times. It helps you to calculate whether your boat will still be afloat at the next low water.
Tidal Stream
A tidal stream is a horizontal flow of water caused by the tide flooding or ebbing across the sea bed.
In an estuary or a channel a tidal stream is linear: it flows in one direction during the flood and in the opposite direction during the ebb.
In the open sea tidal streams may be circular, but will depend on the shape of the tidal basin.
As drawn on the chart a tidal stream is a vector where the direction is in °T (set), and the magnitude is the distance the tide would travel in one hour (knots expressed as miles) (drift).
It is characterised by three arrow heads part way along the line.
Tidal Streams are measured in one-hour intervals, relative to High Water at the Reference port. It is assumed (although, of course, it’s not so) that the set and drift remain constant throughout the tidal hour and then change abruptly at the beginning of the next tidal hour.
Tide
Tides (from low-German 'tiet' = 'time') are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of the Earth.
Most places in the ocean usually experience two high tides and two low tides each day (semi-diurnal tide), but some locations experience only one high and one low tide each day (diurnal tide). The times and amplitude of the tides at the coast are influenced by the alignment of the Sun and Moon, by the pattern of tides in the deep ocean and by the shape of the coastline and near-shore bathymetry.
Tide changes proceed in the following stages:
Sea level rises over several hours, covering the intertidal zone; this is the flood tide.
The water rises to its highest level, reaching high tide (High Water (HW)).
Sea level falls over several hours, revealing the intertidal zone; this is the ebb tide.
The water stops falling, reaching low tide (Low Water (LW)).
The range of a tide is the difference between Height of Tide at HW and Height of Tide at LW.
As the tide rises it moves to cover the intertidal zone: as it falls it moves to uncover the intertidal zone. These oscillating horizontal movements are known as tidal streams. The moment that the tidal stream ceases is called slack water or slack tide. The tidal stream then reverses direction and is said to be turning. Slack water usually occurs near high water and low water, but there are locations where the moments of slack tide differ significantly from those of high and low water.
Many factors contribute to the tides: the primary constituents are the Earth's rotation, the positions of the Moon and the Sun relative to Earth, the Moon's altitude (elevation) above the Earth's equator, and the shape of the basin in which the tide is moving.
The semi-diurnal range (the difference in height between high and low waters over about half a day) varies in a two-week cycle. Approximately twice a month, around new moon and full moon when the Sun, Moon and Earth form a line, the tidal force due to the sun reinforces that due to the moon. The tide's range is then at its maximum: this is called the spring tide.
When the Moon is at first quarter or third quarter, the sun and moon are separated by 90° when viewed from the Earth, and the solar tidal force partially cancels the moon's. At these points in the lunar cycle, the tide's range is at its minimum: this is called the neap tide.
Spring tides result in high waters that are higher than average, low waters that are lower than average, 'slack water' time that is shorter than average and stronger tidal streams than average. Neaps result in less extreme tidal conditions. There is about a seven-day interval between springs and neaps.
There is a delay between the phases of the moon and the effect on the tide. Springs and neaps in the North Sea, for example, are two days behind the new/full moon and first/third quarter moon. This is called the tide's age.
The local bathymetry (the shape and size of the basin) greatly influences the tide's exact time and height at a particular coastal point. There are some extreme cases: the Bay of Fundy, on the East coast of Canada, features the world's largest well-documented tidal ranges, 17 metres (56 ft), because of its shape.
Parts of the South Coast of the United Kingdom (between Chichester and Poole) have a double high water caused by the interaction between the region's different tidal harmonics, caused primarily by the east/west orientation of the English Channel and the fact that when it is high water at Dover it is low water at Land's End (some 300 nautical miles distant) and vice versa. This is contrary to the popular belief that the flow of water around the Isle of Wight creates two high waters. The Isle of Wight is important, however, since it is responsible for the 'Young Flood Stand', which describes the pause of the incoming tide about three hours after low water.
Because the oscillation modes of the Mediterranean Sea and the Baltic Sea do not coincide with any significant astronomical forcing period, their tides have a small range, the largest being close to their narrow connections with the Atlantic Ocean and the North Sea. Extremely small tides also occur for the same reason in the Gulf of Mexico and Sea of Japan. Elsewhere, as along the southern coast of Australia, small tides can be due to the presence of a nearby amphidrome.
The tidal effects observed along the Menai Strait can also be confusing. A rising tide approaches from the south-west, causing the water in the strait to flow north-eastwards as the level rises. The tide also flows around Anglesey until, after a few hours, it starts to flow into the strait in a south-westerly direction from Beaumaris. By the time this happens the tidal flow from the Caernarfon end is weakening and the tide continues to rise in height but the direction of tidal flow is reversed.
A similar sequence is seen in reverse on a falling tide. This means that slack water between the bridges tends to occur approximately one hour before high tide or low tide.
Theoretically it is possible to ford the strait in the Swellies at low water, spring tides when the depth may fall to less than 0.5 metres (1.6 ft). However, at these times a strong tidal stream of around 5 knots is running, making the crossing extremely dangerous. Elsewhere in the strait the minimum depth is never less than 2 metres (6.6 ft) except at the great sand flats at Lavan Sands, N'East of Bangor.
The height of the tide is measured in metres above chart datum, and is recorded alongside the times of High Water and Low Water in a tide table.
The direction of the horizontal movement of the water (the set of the tide) is measured in °True. The speed of the stream (the drift of the tide) is measured in knots. The set and drift are recorded in tables of tidal diamonds on the chart and in tidal stream atlases.
An experimental tide-powered turbine has been built in the entrance to Strangford Lough, in Northern Ireland.
Tiller
The more or less horizontal bar which the helmsman uses to steer the boat. It is connected, directly or indirectly, to the rudder.
Timber
n A piece of wood lying across the length of a vessel (athwartship); typically part of the framing.
Any large piece of wood, other than planks or boards, being a structural part of a vessel.
n Unprocessed wood cut from the tree.
Time
There are 24 hours in a day, from midnight to midnight.
Conventional clocks show only 12 hours (midnight to midday and midday to midnight), but nautical time is measured by the 24-hour clock. Midnight is 0000; 6 am is 0600; midday (noon) is 1200; 6pm is 1800; 1 minute before midnight is 2359.
Midnight to 0600 is morning; 0600 to noon is the forenoon; noon to 1800 is afternoon; 1800 to midnight is evening. See Watches.
There are 60 minutes in every hour and 60 seconds in every minute: minutes of time are not to be confused with minutes of angle (of which there are 60 in every degree).
The Earth rotates from West to East 360 angular degrees in every 24 hours of time, or 15° every hour; the Sun therefore appears to move from East to West.
The world is divided (theoretically) into 24 time zones. Theoretically, the time in each time zone is 1200 (noon) when the sun is directly overhead. (For a map of the time zones, see Universal Time)
But two things distort this.
First, the sun may be early, or late, overhead by as much as 12 minutes.
Second, certain countries opt to belong to a time zone to which geographically they should not belong. For example, France has chosen to align its clocks to Central European time, which is one hour to the East of its geographical position. As another example, Iceland has chosen to align its clocks to GMT, even though it lies one time zone to the West.
The Greenwich Meridian (the Prime Meridian) is an imaginary line through the North Pole, Greenwich (in East London) and the South Pole. It lies at the middle of time zone 0000, which extends from Longitude 7.5° West to Longitude 7.5° East. When the sun is (on average) overhead Greenwich the time is 1200GMT throughout the time zone.
Greenwich Mean Time (GMT) has been replaced by Universal Time (UT) which is not based upon the position of the Sun at noon.
The middle of the Central European Time Zone is 15° to the East of the Prime Meridian. In terrestrial notation it is time zone (UT + 1); in nautical notations it is time zone -0100.
See Universal Time
Tingle
A thin temporary patch, usually of metal, perhaps copper, sometimes lead.
Toerail
A raised beading of wood or extruded metal around the gun’l’ of a boat to help prevent the crew’s feet from slipping overboard.
Toe the line. See Line.
"Do as you're told"
In the sailing days of the (British) Royal Navy sailors were paraded on deck in ranks with their toes at a chalk line on the deck or to a seam in the deck planking.
Tompion
A wooden plug inserted into the end of a gun barrel to keep the barrel dry and delay corrosion.
Tonnage See Thames Tonnage
Top
Platforms at the junctions of the parts of a mast.
They serve to spread as far apart as possible the shrouds for the next part of the mast. Tops are held from below by futtock shrouds. On fighting ships the tops also served as platforms for archers, later for musketmen, who would shoot down at the officers on the quarter deck of the enemy ship. At the Battle of Trafalgar Admiral Nelson was killed by a sniper firing from the fighting top of Redoubtable.
The ship on the right is The Amsterdam, moored in Amsterdam harbour. The foremast, mainmast and mizzenmast shrouds can be seen clearly. The foretop, maintop and mizzentop can be seen. The main topmast shrouds and the fore topmast shrouds can be seen. The fore topgallant shrouds can be seen, as can the main and fore futtock shrouds.
Photograph by Margaret Starkie
The Amsterdam, in Amsterdam harbour
Topgallant
An adjective describing the mast, yard(s), sails, shrouds, stays relating to the topgallant mast, above the topmast, and below the royal mast.
Tophamper
Any superstucture or rigging which is likely to catch the wind and affect deleteriously the navigation of the vessel.
Topmast
The vertical spar, or mast, above the mast and below the topgallant mast.
Folkard thought of a sliding gunter as a form of topmast.
Topping lift
The line which sustains the weight of the end of the boom, and by hauling on which the end of the boom can be raised to the required height, or supported while the sail is reefed or handed or scandalised.
Topsail
A sail attached to the topmast.
The photograph shows a schooner with a square-rigged topsail suspended from a square yard, similar to the topsail of a square-rigged vessel: the photograph also shows a crossjack yard to spread the foot of the sail.
Thames barges usually have triangular fore-and-aft topsails.
Topsides
The sides of a boat between the deck and the water.
Touch and go
A Thames barge tacking in an estuary would continue on a tack until the leeboard touched the bottom: then it would go onto the other tack.
The expression is now applied to any situation where stopping is either momentary or abandoned.
Trainee aircraft pilots practice 'touch and go' landings to save time and fuel.
Tow
v To pull another vessel with warps or chains. To push another vessel.
n The vessel being towed.
See Tug.
Towing
Where one vessel moves another vessel intentionally. IRPCS Rule 24 applies.
One or more tugs may have warps to a larger vessel and guide it into harbour and a berth. One or more of the tugs may push the larger vessel. Those tugs ahead of the larger vessel pull it forward. Those astern or alongside steer the larger vessel.
One or more tugs may pull (unpowered) lighters in an estuary or river by means of warps.
A tug may push a train of barges or lighters to which it is securely attached.
A lifeboat may tow a stricken vessel back to harbour
A friendly boat may tow a broken-down boat back to harbour.
A sailing yacht might tow its tender. The club safety boat will, in calm winds, tow a long line of sailing (racing) dinghies out to the starting line.
There are three ways in which vessels might be towed.
1 In line astern on a long or a short warp.
Yachts which are normally anchored or moored in the roadstead (rather than berthed in a marina) need a dinghy (tender) to get the crew to and from the boat. On passage, the yacht might tow the dinghy astern. At sea, many skippers prefer a long warp so that the dinghy does not bump against the yacht's stern. At close quarters a long warp becomes a nuisance, partly because if the yacht reverses its engine the warp may become caught in the propeller. For this reason many skippers use a very short warp, which is bright yellow and which floats.
2 Alongside.
Towing alongside is most convenient in calm water; in a seaway the two vessels will rise and fall, pitch and roll at different times and frequencies.
The tow has a line from its stern quarter to a cleat amidships the tug; it is this line which tows. The line from the tow's bow to the tug's bow (a breastrope) is simply to keep the tow alongside; properly adjusted, it may allow the tow's head to fall away from the tug and keep the two vessels slightly apart. A breastrope from the tug's stern to the tow's stern keeps the tow the correct distance from the tug.
3 By pushing.
The stems of most commercial harbour tugs are adapted for pushing. The barges or lighters to be pushed are tightly and securely attached to the tug so that the two (or many) behave as a single vessel.
The tugs which manoeuvre large ships in harbour are similarly adapted, but are not normally attached to the ship when pushing.
Tradewinds
Easterly winds that blow consistently in the same direction. They prevail in areas about thirty degrees North and South of the Equator.
At the Equator warmer, less dense air rises to a height of, perhaps, 11 kilometres. Some of the air moves North, some moves South at altitude. At latitude 30 or 40°N (and S) this air falls (as colder air). At the surface it moves South (and North) to replace the rising, warmer Equatorial air. As it moves, the Coriolis Force, resulting from the rotation of the Earth, displaces the surface air to the West, causing an Easterly wind.
This consistent Easterly wind carried sailing ships westward along trading routes.
Traffic Separation Scheme
A means of keeping apart large vessels travelling in opposite directions in busy, but deep, waters. Corridors or lanes to which large vessels are constrained in the open sea. The beginning and end of a separation scheme may be marked with Special buoys or Safe Water Marks but the corridors, or lanes, are defined by GNSS, occasionally by Channel Markers. Not to be confused with channels.
See IRPCS Rule 10
See TSS, below.
Trailer
A wheeled vehicle to be towed behind another wheeled vehicle and to carry cargo (or boats) but never passengers.
Trailer-sailer
A boat which can be drawn on a trailer from one cruising water to another.
Almost any boat can be carried on a road trailer, but larger boats are more difficult to lift out of and into the water than smaller boats; dinghies are relatively easy. Trailer-sailers are larger than most dinghies and usually have an enclosed cabin. They may be up to 30 feet (9m) in length and rarely less than eighteen (5.5m). They often have a centreboard or. more rarely, one or more daggerboards or occasionally leeboards.
Transceiver
Both a transmitter and a receiver.
The transceiver of an echo sounder transmits sound waves and receives the echoes.
Transit
When two features in sight of the boat are in line, on the same bearing. The most useful of all aids to pilotage. When two features can be seen in line the boat must be somewhere on the extended line.
Many harbours and ports have lights and/or posts (see leading line) which form a transit for safe entry to the harbour. Leading lines, and the characteristics of their lights and shapes, are shown on charts.
Skippers of small boats often establish their own transits using features such as trees, buildings, pylons.
In the USA a transit is known as a range.
Transom
n The flat or curved, vertical or sloping part of the boat at the stern from the deck to the waterline (and below).
n A transverse horizontal structural beam or bar, typically above a door. In the Age of Sail the transoms of a ship were the horizontal beams which, together with the fashion pieces, formed the framework for the stern of a ship.
Traveller
n A slide which travels on a track to which the mainsheet may be attached. The sail shape can be subtly altered by changing the mainsheet position on the traveler.
n A person who travels.
Trawler
A fishing vessel which drags a net ( a trawl) across the bottom of the sea.
Triangle
A mathematical figure with three sides. The sides are lines which might be straight or curved.
A triangle of vectors is a graphical means of calculating a course to steer through a tideway or of estimating a future position while sailing in a tideway.
A vector is a straight line (on paper) representing both direction and magnitude. The angle which the line has with a linear datum (True North when drawn on a chart) gives the direction; the length of the line gives the magnitude.
The three lines of a triangle of vectors are Heading & Speed (through the water) of the boat, Set & Drift of the tide, Direction & Speed over the ground. When drawn on a chart the triangle represents a fixed period of time (perhaps one hour to correspond with a tidal hour) so that Speed is reduced to distance within the fixed period of time.
In calculating a Course to Steer one vector (tidal Set and Drift) is known; parts of the other two (Course over the ground and boat Speed through the water) are known, and are used to calculate the boat's Heading and its Speed over the ground.
In Estimating a future Position two vectors (tidal Set and Drift, and boat Heading and Speed) are known; they are used to calculate the Course over the ground and Speed over the ground.
A brass triangle on the deck of a Ship of the Line was supposed to carry a pile of 4 cannon balls; one in each corner of the triangle and one on top. The brass triangle may have been known as a monkey.
A nautical myth suggests that in very cold weather the brass monkey would contract more than the iron balls and then the balls would roll off the monkey.
In fact, the coefficient of expansion (or contraction) of brass with heat (or cold) is not so different from that of iron that this could happen within the temperature range compatible with the life of the crew.
There is little evidence that brass triangles were used to hold cannon balls on deck; balls were usually held in wooden racks (garlands).
Tree-nail
A hard-wood pin, similar to a dowel, used as a fastening in the place of a metallic bolt.
Usually corrupted to tr'n'l, and pronounced either 'trunnel' or 'trennel'.
Trestle trees
Fore and aft pieces on each side of a mast resting on the hounds to support the rigging and cross-trees.
Triatic stay
A stay from the top of the main mast to the top of the mizzen mast. They often carry, or have built into them, radio aerials (antenna).
Tricolour
A running light allowed on sailboats less than 20m long instead of the normal side and stern lights. The tricolor light contains the red and green side lights and the white stern light in a single fitting that is attached to the top of the mast. This is neither a ‘masthead light’ nor an all-round light.
IRPCS Rule 25, “Sailing vessels underway and vessels under oars” says:
(a) A sailing vessel underway shall exhibit:
(i) sidelights;
(ii) a sternlight.
(b) In a sailing vessel of less than 20 metres in length the lights prescribed in paragraph (a) of this Rule may be combined in one lantern carried at or near the top of the mast where it can best be seen.”
Rule 21 “Definitions” says:
“(b) "Sidelights” means a green light on the starboard side and a red light on the port side each showing an unbroken light over an arc of the horizon of 112.5 degrees and so fixed as to show the light from right ahead to 22.5 degrees abaft the beam on its respective side. . . .
(c) “Sternlight” means a white light placed as nearly as practicable at the stern showing an unbroken light over an arc of 135 degrees and so fixed as to show the light from 67.5 degrees from right aft on each side of the vessel.”
The advantage for a small sailing boat is that a single bulb in a tricolour fitting uses less power than 3 separate bulbs in 3 separate fittings. Power-hungry incandescent bulbs can now be replaced with Light Emitting Diodes, which use relatively little power.
Trice
v To haul and secure by means of a tricing line. A gaff-rigged sail may be scandalised by tricing the tack up to the throat.
A similar means of furling a sprit-sail, by hauling the clew up to the throat, is known as 'brailing'.
Trick
A period of duty connected with the navigation of a vessel; more particularly, at the helm or look-out.
Trim
vb To adjust the sails so as to utilize their maximum efficiency.
From this perspective there are just two points of sail: hard on the wind and off the wind. With the boat hard on the wind (close-hauled) the sheets are hauled in closely and the helmsman adjusts the heading to give best speed or best angle to the wind. With the boat off the wind (reaching or running) the helmsman steers a compass course while the crew trims the sails for best speed and efficiency.
vb To adjust the horizontal attitude of the boat for maximum speed through the water.
Many power boats are fitted with trim tabs below water on the transom to adjust the trim of the boat while under power.
Dinghy sailors will move to different positions in their boat to alter the trim to maximise their speed and reduce the risk of capsize.
Racing yachtscrew will often sit on the windward rail in a futile attempt to reduce the heel of their boat.
adj Tidy. Smart. Pleasing to the eye. 'Ship-shape and Bristol fashion'. "She's a trim little craft"
Trimaran
A vessel with three hulls. The two outer hulls may be smaller than the central hull and may exist only to keep the boat upright.
A sailing trimaran may have only two of the hulls in the water; the third, the windward hull, is 'flying'.
Three long, thin hulls offer less frictional resistance than a single large hull, so trimarans sail faster, or use less power, than monohulls.
Trireme
A vessel, probably invented by the Phoenicians but developed by the ancient Greeks, which had three banks of oars along the length of the vessel.
Tripping line
A light line attached to the crown of an anchor close to the flukes; ie, at the opposite end to the attachment of the rode. The other end of the tripping line is attached to a buoy floating at the surface or to the boat.
Its purpose is to invert the anchor and to pull it out of the ground flukes first, if the flukes have become stuck under a rock or cable or mooring chain.
Trot
A row of moorings along a single mooring-chain.
See the photograph under Mooring.
Truck
A wooden cap at the top of a flag-staff or a mast with holes or sheaves for ha'lyards. A truck at the top of a mast is also fitted to receive the spindle of a lightning-rod.
True Bearing
TSS
Traffic Separation Scheme. Consult the IRPCS, Rule 10.
Rule 10 "Traffic separation schemes" says
"(a) This Rule applies to traffic separation schemes adopted by the Organization and does not relieve any vessel of her obligation under any other Rule. . .
(j) A vessel of less than 20 metres in length or a sailing vessel shall not impede the safe passage of a power-driven vessel following a traffic lane."
In the light of Rule 10(a), Rule 10(j) does not conflict with Rule 18(a).
Rule 18 "Responsibilities between vessels" says
Except where Rules 9,10 and 13 otherwise require
(a) A power-driven vessel underway shall keep out of the way of:
(i) a vessel not under command;
(ii) a vessel restricted in her ability to manoeuvre;
(iii) a vessel engaged in fishing;
(iv) a sailing vessel."
Tug
A specialised boat which manoeuvres another vessel by pulling or pushing. See Tow, Towing.
True North
The direction of the geographical North Pole.
Trysail
A small heavy sail, usually triangular in shape, hoisted in heavy weather in place of a larger (usually Bermudan or gaff) sail.
Tumblehome
The beam of the vessel at the sheer or gunwale is less that its beam below the sheer. Where a vessel’s maximum beam is below the sheer or gunwale.
Turn
A bight of line which passes fully round an object, such as a cleat or a spar, as part of a hitch.
Turnbuckle
See Bottlescrew
Tye
A line which joins the block of the ha'lyard to the gaff or yard.
A ha'lyard runs from the heel of the mast to a sheave high on the mast, then down to a block near the gaff, and then back to fasten to a point high on the mast. The block acts as a purchase, halving the effort required to haul. The block is linked to the gaff by a tye.
See Falconer
John Starkie
October 2020
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