Sierra (Phonetic)

Sound signals – One to starboard, two to port, and three astern. The single letter S means, ‘My engines are going astern’, thus matching three hoots nearly (and intentionally) with the three dots Morse code for S. Sierra is the word in phonetic


A wooden block on a spar, affording a rest for another spar, or for a stay. A Gaff saddle is similar in form to a riding saddle, the mast taking the role of the horse’s back. It is made of metal, but covered with rawhide to lessen chafe.

Sag, to

(1) A hull ashore, supported only at her ends, will sag in the middle. (See also: Hogged)

(2) Usually in combination as in ‘sag away to leeward’, or ‘sag off, it des­cribes a boat making rather too much Leeway when sailing on the wind. Typical small family cruisers tend to sag away most badly when the sea is rough enough to slow their forward progress.


Both noun and verb: on a sailing boat you set a sail. Also used: raise your anchor and ‘set sail’. Oil tankers ‘sail’ at their departure times, and sometimes a steamship is said to ‘set sail’ in the meaning that she sets forth. Only when a boat has both sail and power as her means of propulsion does one take care to distinguish between the verbs ‘to sail’ and ‘to motor’.

Sail area

The sail area of a boat is variable, to accommodate to the wind strength. A common reference-point is the ‘working sail area’, which is not precisely defined, but may be taken to mean the total area of the sails that the boat would set in winds of Force 3 to 4.

Sail area/displacement ratio

Like the Displacement/Length Ratio, this is a useful parameter in comparing one boat with another. The sail area is nominal, being that which is enclosed by two triangles, one representing the mainsail, and the other the area between mast, forestay and foredeck. Divide that by the displacement to the power of 2/3. Use square feet for sail area and long tons 2,240lb for displacement.

Sail cloth

Any sort of textile used for making sails. But each sail is made up of several pieces, each of which is known as a cloth

Sail on her ear, to

To sail a boat at a large angle of heel, say with the lee rail awash.

Sail plan

The drawing which shows the positions and sizes of sail, and of the spars and rigging, though there may be a separate and additional rigging plan

Sail-tie, or sail-stop

A length of rope, canvas or bungee, which is used to tie a furled sail. Also called Gaskets, especially by square-rigged types.

Sailing directions

Instructions as to pilotage – not to the handling of the boat herself. Sailing directions usually take the form of a book, and the term is almost synonymous with Pilot.

Saint Elmo’s fire

A corona discharge of static electricity from a boat’s mast or her rigging. You may never see it, and when you do there’s nothing you can do about it, so try to relax and enjoy the spectacle. It is silent, and not of itself dangerous. May be accompanied by a smell of ‘ozone’ or of ‘sparks’


A low-lying area which is flooded at high tide. Ing was an old word for field or meadow.


In marine affairs has the same meaning as it does ashore – of things saved (such as members of the Salvation Army). But there is the specifically nautical usage (with legal implications) where a service of salvage is performed and, if proved in court, may merit an award of money. The amount of the award will relate to the value of property salvaged, the extent of the danger to that property, and the risks or difficulties overcome by the salvors

Samson post

A strong wooden post rooted in the keel and passing up through the deck where the top eight or twelve inches provide a strong attachment point for the anchor cable, or for mooring and towing warps.

Sandwich construction

A form of construction used for hulls, decks and houses, in which two relatively dense skins are held apart and stabilised by a thicker core of lightweight material. The core may be of balsa wood, for example, or of foamed plastic. The idea is to save weight and achieve stiffness, for although a thick skin of plastic material may be quite strong it will bend easily. Two such skins held apart and prevented from buckling by an inner core can be a hundred times stiffer than either alone. But it is essential to get a good bond between skins and core, and to be sure that there are no cavities into which water could penetrate.


Search and Rescue (organisation or activity)


Search And Rescue Transponder. A device which responds to X-band (9GHz) radar to help locate survivors. SARTs which send AIS position reports were also introduced in January 2010.


Satellite Based Augmentation System. A network of ground stations which augment a satellite navigation system such as GPS by calculating the error of the raw satellite fix and communicating it back to the satellite to be passed on to users.

Scandalise, to

A gaff mainsail is scandalised by lowering the Peak, and by Tricing up the Tack so that the foot of the sail is raised and the area reduced for less power in higher winds. Trice can properly be used for the action of lifting anything upwards and out of the way by means of a rope.


To a shipwright, speaking of timber, means no more than the dimensions to which it is to be cut or shaped. If you say, ‘Let’s look at her scantlings’, you are going to assess the stoutness of her timbers, carlins, floors and so forth. (See also: Moulded and sided.)


This is the horizontal or fore-and-aft movement of a boat under the influence of waves – usually most noticeable in harbour. It is also the vertical movement (due to waves) of the water itself against a harbour wall, for example.


A two masted fore-and-aft rigged sailing vessel with the taller mast aft. Naturally enough this mast is the mainmast and carries the mainsail. The foremast carries the foresail, usually with its foot on a boom like a smaller mainsail. Ahead of the foresail will be one or more Headsails.


The length of anchor cable or mooring rope. When anchoring it is always wise to give plenty of scope, by Veering plenty of cable.


The groove made in the shell of a block to take the rope strop which surrounds it. A similar groove provided to locate a rope on a spar.


Various designs of small boat. In the USA a scow is long, lean, and of boxlike cross-section, with bilgeboards – like centreboards – port and starboard. But in Britain a scow is likely to be a clinker dinghy, eleven or twelve feet long, shallow in the body but be amy, and setting a lugsail.

Scow an anchor, to

To attach the anchor cable to the Crown of the anchor, and then seize it to the ring with a suitable twine or marling. While the pull is along the Shank no great load is put on the seizing, but if the anchor is foul the seizing will part when the cable is hauled up short and the strain comes at an angle to the shank. When the seizing parts the pull comes directly on the crown of the anchor, whose fluke should be pulled clear.


A trade-marked name for a type of resin infusion.

Scull, to

To the river boatman it is to pull a boat with a pair of oars. To the seagoing boatman it is to propel a boat with a single oar over the stern by sweeping it from side to side while twisting it. A good dinghy will have a half-round sculling-notch in the transom to take the single oar. (See also: Wangle, to.)


An opening in a Bulwark to allow water to run off the deck.


More commonly called a porthole or portlight. A round opening window in a heavy metal frame.

Sea anchor

A drogue, or parachute-like construction, of timber, iron and heavy canvas, designed to resist being dragged through the water. In heavy weather a sea anchor may be streamed over the bow of a boat with the idea that it will hold her head to wind and seas as she drifts stern-first before the storm. Some people believe that sea anchors are effective, many others have been disappointed, and the whole business has provided much material for usually inconclusive argument. Some boats will lie to some sea anchors, others will not.

Sea breeze

A wind flowing in from the sea to replace air over the land which rises due to the day-time heating by the sun. A land breeze blows the other way when, at night, the land cools more rapidly than the sea.

Sea kindly

Describes a hull which rides comfortably at sea, whose motion is neither too lively nor too sluggish, and whose decks do not ship too much water. A sea kindly boat defies precise definition, but is recognisable as soon as you take her out.

Sea mile

A Nautical mile.

Sea room

Sufficient space to manoeuvre and to do what you wish to do without obstruction by other ships, the land, shallows, or man-made constructions such as piers.


A valve on a Skin fitting to control the ingress or egress of water.


The gap between two planks of either the hull or the deck. Seams are Payed with caulking on a bed of cotton or oakum. In a sail or tarpaulin, ‘seam’ has its ordinary meaning


The art and science of keeping out of trouble at sea, no matter whether your craft is a fully-rigged ship or a makeshift raft.

Secondary port

Times of High and Low water are predicted for every day of the year for a few primary or Standard ports. The times for secondary ports are found by reference to the times at standard ports.


If you were to cut through a hull as if cutting a slice of bread from a loaf you would see the shape of the section at that point. Designers commonly draw ten sections for a modest-sized hull, of which the midship section, or midsection, is sometimes called the ‘master section’ since it sets the shape for all the others and does much to stamp a character on the hull as a whole. (See also: Lines, Bilge and Chine.)


(pronounced saysh) A rise and fall of the water level in a marina or harbour occurring at an interval of a few minutes and unre!ated to the ordinary tidal rise and fall or to regular swell running in from the sea. May be caused by changes in barometric pressure, or by waves of very long period which would not be noticeable in the open sea. In ordinary landsman’s language you would probably say ‘surge’.

Seize, to

To bind together two ropes, two spars, or almost anything to anything with several tight turns of small cord. The result is a Seizing. A Racking seizing goes over and between in a fIgure-eight pattern, instead of straight round the outside.

Selective Availability (SA)

A system by which the US military could dilute the accuracy of, or even switch off, GPS. The US government has now undertaken not to use the system, and future GPS satellites will not have the facility for SA.


A special type of drain for sailing dinghies in which water is drawn out either by the attitude of the hull which causes it to run aft, or by the lowered dynamic pressure on the outer skin resulting from the high forward speed. Either of those conditions is best satisfIed when a dinghy is planing. A cruising boat whose cockpit sole is several inches above the waterline may have drains, and will usually be called ‘self-draining’, though some people might call it self-bailing. But such simple drains are never termed ‘self-bailers’.


See Auto-pilot.


A phrase that describes a sail whose sheet calls for no attention when passing from one tack to another. A conventional mainsail is self-tacking, but conventional jibs are not. A headsail can be made self-tacking either by bending a boom or club along its foot, or by leading its sheet to a traveller which is free to slide along a Horse across the foredeck.

Self-tacking jib

A non-overlapping headsail, usually sheeted to a track or horse, that can be left to its own devices in a tack.

Self-tailing winch

A winch that grips the tail of a rope to allow single-handed winching.

Senhouse slip

One form of slip hook for quick release. The Pelican hook is similar. The hinged tongue of the hook is held closed by a ring, and when the ring is knocked free the tongue flies open.


Plaited or woven rope in more or less fanciful patterns.

Serve, to

To cover a rope or a splice by binding Marline or other Small stuff tightly around it. Where the end of a rope is served (to prevent fraying) the process (and the result) is commonly called Whipping.

Servo rudder, 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. (See also: Vane gear.)


Both verb and noun. A boat carried by the stream of a tide may be set to the west, or she may set towards the mouth of a river by the current. In either case one may say that there ‘is a set’ to the west, or towards the mouth.

Severe gale (in shipping forecast)

Winds of force 9 (41-47 knots)


An optical instrument for measuring angles, such as that between the sun and the horizon, between the top of a lighthouse and the sea at its base, or (with the sextant turned on its side) between two objects ashore.


(l) A metal link which can be opened or closed. The most common is U-shaped and is called a D-shackle, the open part of the U being closed by a threaded pin.

(2) A measure of length – and rather variable from place to place. Usually fIfteen fathoms, and relates only to chain cable.

Shaft log

A strengthening member fitted on the Keel, Keelson or Deadwood where the Stern tube passes through the hull. Originally a shaped lump of timber, such logs may nowadays be made entirely of metal.


The central ‘stalk’ of an anchor.

Shape a course, to

To decide a course, and set the ship’s head on it. Commonly one shapes a course ‘for’ or toward some specific point or place, since the vagaries of weather and sea may enforce alterations to the plan


A boat of simple hull form, with more or less flat bottom, and more or less flat sides, running together at the stem. Sharpies may be small pulling boats, small open dinghies, or decked cruising boats with cabins. The bigger sizes, fitted with leeboards, are relatively common on New England waters.

Sheathe, to

To cover a hull or deck, usually a wooden one, with an impervious layer. The technique which appeals to many DIY-ers is to sheathe the boat with glass cloth (or chopped strand mat) and polyester resin. Unfortunately, polyester does not always bond very well to the timber – epoxy resin would better, but it is harder to work with and more expensive. There are proprietary types of sheathing, some based on rubbery compounds, others using reinforced plastics. All require that the wood beneath be sound, free from rot, and free from paint, oil, or large gaps and cracks. Copper sheathing was formerly much used to protect wooden hulls against Teredo in tropical waters. Although copper sheet is very expensive, the initial capital cost is offset by the saving of the annual anti-fouling paint which would otherwise be necessary, so in the long term sheathing may prove cheaper as well as more convenient.


The actual wheel of a pulley Block. Special types of sheave are made for rope, wire and chain. The larger the diameter of the sheave the more easily the cable will run, and there is a definite minimum size for each size of cable. The size of block is proportioned to size of rope, with sheave diameter, Score and Swallow all in harmony. The noticeably large sheaves used with small ropes in the multi-part mainsheet tackles on some racing dinghies are made that way for easier Rendering – in other words for maximum mechanical efficiency.


The curve of a boat’s gunwale or top strake when viewed from the side. The Sheer plan is a drawing of the side elevation. A conventional sheer runs down from a high point at the stem, reaches its lowest somewhere near amidships or a little aft of that, and then rises again towards the stern. A hogged sheer is the reverse – hump-backed and piglike.

Sheer legs, sheers or jeers

Long poles, spars or struts, two or three in number, set up to lift and step a mast, say, or to lower an engine into a boat.

Sheer pole

A rod or stick fIxed between the lower ends of a pair of shrouds so that neither of them can twist.

Sheer strake

The topmost plank in a boat’s side.

Sheer, to

To put the rudder over to one side. Sometimes done when a boat is at anchor, to make her lie to one side and more steadily: this is called ‘giving her a sheer to port’, for example. (See also: Cast, to.)


A line that controls the lateral movement of a sail. Normally attached to the clew, it adjusts the sail’s setting for the relevant wind angle.

Sheet bend

Knot for joining two ropes of unequal thickness

Sheet Lead

Usually relating to a headsail sheet, this refers to the run of the sheet. The sheet must be run so that it is free of snags and correctly positioned to ensure the best sail shape. Most yachts have moveable traveller cars, which allows a sailor to adjust the angle of the headsail sheet and thus the sheet lead for different sails, weather conditions and wind strengths.


In timber construction the shelf is a component running fore and aft along the tops of the ribs, and providing support and attachment for the deck beams.


The outer casing, or shell, of a block.


See: boat

Ship’s papers

Mainly the certificate of registry, but also any documents pertaining directly to that particular boat, such as receipts for harbour dues, customs clearances, and so forth.

Ship, to

To set a component or part in its working position. Oars must be shipped in their rowlocks before you start rowing. Later they will be unshipped … and then ‘boated’. You ‘ship’ winch-handles in their sockets, or oil lamps on their brackets. Also used to mean taking anything on board, from a cargo to a crew, from a sewing machine to a large wave

Shipping forecast

Maritime weather forecast for the next 24 hours covering the 31 sea areas of the Atlantic coast of Europe and the North Sea


In good order, tidy and efficient.


A place where the water is relatively shallow. The word is noun, adjective and verb. ‘There is a shoal over there.’ ‘The water is pretty shoal over there.’ ‘The water shoals quite quickly on the eastern bank.’


(boat) One designed to float in less water than the average for her size. Usually tends to be beamy.


Where the land meets the sea; also a strut used to prop up a boat on dry land.

Shore power

Mains electricity supplied by cable to a boat from the shore.

Shorten sail

To reduce the total sail area set, either by reefing, or by Handing or Furling one or more of those in use.


The shoulders of a boat are at the fore-part of the hull, just abaft her head.

Shroud plate

The fitting on the hull to which a shroud or stay is secured. (See also: Chain plates.)


Stays, usually of wire rope, supporting the mast at each side. Cap shrouds go to the top of the mast, ‘lowers’ go to some intermediate point, often about two-thirds of the way up, where Spreaders are fitted.


A spinnaker set to receive a wind more or less on the beam, instead of over the stern, is said to be set shy.


The red (port) and green (starboard) navigation lights fitted at the sides of a boat

Single up, to

To cast off all mooring lines, except one at each end of the boat, preparatory to getting under way.


A shallow keel at the after end of a boat, or a deeper fin giving support to the rudder. Can also protect the rudder or propeller when the boat grounds.

Skin drag

The water resistance to a boat going through the water comes from several causes. Of these one is skin friction. This is minimised by maintaining a clean and smooth hull surface (though a highly polished one is not always the best). Weeds, barnacles and bumps of that sort make the skin drag very much greater. (See also: Drag.)

Skin fittings

This term embraces a variety of components associated with necessary holes in the hull. For the main part, such fittings take the form of metal or plastics pipes with flanges and backing plates. Sometimes an inlet fitting will have a coarse integral strainer to keep out the bigger particles of seaweed. A seacock itself may on occasions be termed a ‘skin fitting’, though in other contexts a distinction would be made between the seacock and the skin fitting to which it is screwed. It is good practice to reinforce the hull in the region of a skin fitting, usually with a backing pad. The fitting must be well bedded, and bolts or other fastenings must be of a material which will not corrode in sea water nor set up a galvanic action with the material of the fitting itself.


Either a qualified master or whoever is in charge of the vessel – responsible for the vessel and all those on board. On larger boats, often not the same person as the owner

Slack water

The time at High water, or Low, when the tide ceases to run


The rattling, shaking movement and noise of sails which are fluttering in the wind and are not filled and drawing. To a seaman this is an irritating sound, partly because the sails and gear are being worn out to no good purpose.


A smooth patch of water or a patch of oil in the water. A water slick may form in the lee of a hull, or by reason of some tidal current effect.


Small, specially shaped pieces of metal or plastic which are attached to the Luff or mainsail and hold it to the mast by sliding in the Track

Slight (in shipping forecast)

Wave height of 0.5 to 1.25 m

Slip hook

See: Senhouse slip.

Slip, to

A boat is slipped when she is brought to the slipway and there grounded or settled into a mobile cradle. Like so many other nautical words, ‘to slip’ has other meanings, notably to drop your mooring, or simply to cast off from a quayside: ‘We slipped at 0400 and, once clear of the harbour wall, laid for the headland on port tack. . .’ Also: to slip your cable. If you’re anchor is stuck, Having first buoyed it, you free the Bitter end from the boat and drop it all overboard, hoping to return and retrieve it some sunnier day.


A firm sloping roadway, of concrete, railroad sleepers, etc., running down into the water for the convenient launching and retrieval (slipping) of boats. Known as a ‘slip’ colloquially.


Definitions vary from era to era and place to place. Current usage, though tends to reserve it for fore-and-aft rigged yachts of moderate size, setting only a mainsail and one headsail. A few hundred years ago a sloop, insofar as rig was concerned, would have had a short fixed bowsprit while a Cutter would have had a longer but reefable bowsprit. The cutter could thus carry more sail in light airs and tended to be the choice when speed was required – as in smuggling. Speed was also required by the revenue men to chase the smugglers, so they adopted the cutter rig too. Today, usage links ‘cutter’ with a two-headsail rig (staysail and jib), and that is not infrequently allied to a fixed bowsprit much shorter than those of the old-time cutters. At the same time, the modern sloop has lost her bowsprit completely and sets her single headsail to the stemhead. But note that her overhanging bow may carry the stemhead farther forward than that of the old-fashioned sloop with her straight-up stem – in effect many a modern sloop has integrated a short bowsprit into the hull structure itself. (See also: Cutter.)

Slot effect

The ‘slot’ is the gap formed between Headsail and Mainsail. The best way to sum it up is to say that if you have a sail behind a mast, you can improve the airflow over the lee side by careful adjustment of an overlapping headsail. The slot so formed will speed up the air flow over the lee side of the main and reduce the turbulence caused by the mast. But the slot is not a propulsive device of itself: if you were to make a single sail equal to the combined area of main and jib, and if you were to hank it on a forestay so that it was free of the mast’s turbulence, its propulsive effect would be greater than that of the two sails and their slot.

Slowly (in shipping forecast)

Moving at less than 15 knots


A word that is something of a rarity which was coined by Ocean racer design guru, John lllingworth (1903-1980) for a rig which has something of the sloop and something of the cutter. Only one headsail is set at a time, but there is a choice of two, one of which is set to the masthead (light weather) and the other to some lower point on the mast (stronger winds).

Smooth (in shipping forecast)

Wave height less than 0.5 m


Society of Naval Architects

Snap shackle

There are various kinds, but all use spring loaded pins that don’t separate from the D-ring and should therefore not go over the side when undone. Can be operated one-handed and under load

Snatch block

A block whose shell can be hinged open at one side to allow the rapid insertion of a rope without reeving it all the way from the end.

Snub, to

To jerk on a rope or a chain sharply. The boat may do it herself, snubbing at her anchor cable in heavy weather – that’s to say coming up short on the cable with a jerk. A Snubbing winch is a small winch consisting of a drum with no lever but with a ratchet mechanism so that when you shorten a rope turned around the drum it acts as a brake. A snubbing line has a hook on the end that goes through a link in the anchor chain to take the strain off the windlass.


A sock-like device used to deploy and recover a spinnaker or cruising chute.

Soft eye

A plain eye in the end of a rope, without a Thimble.

Soft shackle

A strop, made from Aramid fibre used in place of a metal shackle, to save weight.


Speed Over Ground. The speed made by a vessel at any given time after tide and leeway have been taken into account, usually as measured by GPS.


Acronym for the protocols laid down in the International Convention for the Safety of Life at Sea 1974 organised by the International Maritime Organisation (IMO). The SOLAS Convention in its successive forms is generally regarded as the most important of all international treaties concerning the safety of merchant ships. The first version was adopted in 1914, in response to the Titanic disaster, the second in 1929, the third in 1948, and the fourth in 1960.


Chapter 5 of the International Convention for the Safety of Life at Sea (SOLAS), parts of which apply specifically to small, privately owned pleasure craft.

Soldier’s wind

A fair or free wind that saves you having to sail Close-hauled.


The sailor’s word for the floor. You stand on the cabin sole, or the cockpit sole. But dinghies usually have Bottom boards or Gratings, not soles. (See also: Floor)

Solent rig

A jocular term for what is sometimes said to be the weekend yachtsman’s preferred rig – that’s to say no headsail, mainsail set but strapped down hard, while the boat proceeds under power.

Solent stay

A removable inner forestay, just inside the main forestay, on which a smaller headsail can be set.

Solid laminate

The layup of a hull, deck or other structure that does not include any form of stiffening material between the layers of fibre and resin.


A system for ascertaining the distance to an object using sound. On leisure craft, this is usually an echosounder or fishfinder.


In weather terminology, Soon means that the forecast weather is expected to arrive within twelve hours. See also: Imminent.


As a noun it means a navigable passage between two sea areas, or an arm of the sea or large inlet, with good depths. As an adjective it means ‘in good condition’

Sound, to

To find the depth of the water, by means of an Echo sounder or a Lead line, or just a long pole. Hence a sounding.

Soundings, in soundings

Approaching land from the ocean, a ship reaches the point where the water shallows sufficiently to permit soundings to be taken – say about 100 fathoms. She is then ‘in soundings’.

South cone

A black cone hoisted by Coastguards, harbourmasters and other shore side officials to indicate the expectation of a gale from a generally southerly direction. The point is downward. By night three (usually red) lamps are suspended in the form of a triangle, point down. A North cone is the other way up.


Usually a wire, but could be rope or chain, stretched between two points to spread the load. A dinghy to be lifted on deck could have a wire span from stem to transom, the lifting tackle being attached at roughly the mid point of the span. The yard of a gunter sail sometimes has a wire span along its length to which the peak halyard is attached.


On a square rigged ship, the spanker is a gaff rigged fore-and-aft sail set from and aft of the aftmost mast. More often now called a Mizzen or a Jigger. (In old books you may also find the same sail called a ‘driver’.) The sail which the Dutch sometimes set from masthead to stern, and which they call an aap (ape), could well be called spanker in English.


Mast, boom, gaff, yard, spinnaker pole … all are spars. It is the general term for sticks or poles used as part of a boat’s rig, whether made of wood, metal or any other material that may come along. (See also: Yard)

Spar buoy

A buoy with a vertical pole sticking up through its middle so that it looks like a toffee-apple dropped sticky end down

Speak a ship, to

Old nautical term meaning To communicate with another ship at sea using flags, Aldis lamp, or by any other means


See Aramid.

Speed/length ratio

This ratio is abbreviated as V/√L. It is the speed in knots divided by the square root of the waterline length in feet. For example, a boat with 25 foot WL gives a square root of 5. Then, when she is moving at 5 knots her speed/length ratio is exactly one. At a speed of 10 knots her ratio would be two. The ratio is of significance for Displacement hulls (ie. those which don’t plane on the water) because it is rarely that such hulls achieve better than a speed/length ratio of 1.5. In fact most don’t do as well as that: a ballasted sailing boat of 25 foot waterline would do well to achieve a ratio of 1.3 and to sail at 6.5 knots, though she might easily do it with a 30 horsepower engine in calm water.

Spherical buoy

According to the international buoyage system a spherical buoy has no port/starboard significance, but if painted orange is used as a ‘special mark’ to indicate such things as practice zones, sewer outfalls and such odds and ends. If painted in red and white vertical stripes it indicates safe water, and you may pass either side.

Spider band

A metal band carrying a number of eyes, lugs or other pick-up points which is fitted around a spar for the attachment of stays, or simply to house Belaying pins.


Usually a Marline spike


A large parachute-like headsail of very light material used mainly for running downwind, but also carried in a beam wind when it is said to be set Shy. First introduced in 1865, the spinnaker was not always so balloon-shaped as it commonly is today, and even now a smaller and flatter type is used by some cruising owners. The sail is set with a pole to one lower corner, controlled by the Guy, and has a sheet to the other corner, though those who are not constrained by racing rules may use two poles, or none, or they may opt for a cruising chute.

Spinnaker chute

A tubular container lying along the underside of the deck with a bell-mouth emerging through the deck near the stem. The spinnaker can be housed in the chute with its halyard attached, ready for rapid hoisting when the boat turns on to the downwind leg of the race.

Spinnaker sleeve (or sock)

A long sleeve of light cloth in which the spinnaker is hauled aloft. The sail is then broken out by gathering the sleeve up at the head of the sail, for which purpose it has its own continuous halyard-cum-downhaul.


Either a narrow strip of land projecting into the seaway, or a submerged shoal of long and narrow shape – one that is longer and narrower than a Horse.


A small Headsail Gib of heavy canvas and stoutly roped, to be set in the heaviest weather. Nowadays more commonly known as a ‘storm jib’.

Splice, to

To join two pieces of rope by interweaving the strands. The resulting joint is a splice. In the Eye-splice the rope’s end is turned back and woven into itself to form a loop.

In the Back splice the three strands are formed into a Crown knot and then immediately tucked back into the rope to make a thickened end which will not unravel.

The Cut splice is made by splicing the two ends of a short piece of rope into the body of a longer piece, rather like the handle of a a basket.

The short splice and long splice join two pieces of rope end-to-end. In the Short splice the strands of each rope are unlaid, then the ropes are married together and the strands of each are tucked under the still-laid strands of the other, working against the lay. The splice is thicker than the body of the rope because it contains six strands instead of the normal three.

The Long splice is quite different. Strands in each rope are unlaid for a greater length and the ropes are married. A strand of one rope is then unlaid for an even greater length, and a strand of the other is laid up in its place. The procedure is repeated for the other rope. The remaining two strands (one from each rope) are cut where they meet at the middle of the splice, allowing enough to tie them together with a reef knot. The other matching pairs of strands are similarly tied. The result is barely thicker than the original rope, but not very strong and consequently not much used.


To the shipwright a spline is a thin strip of wood which is glued into a seam when the gap is too wide for ordinary caulking. Similarly a spline may be used to repair a cracked plank, after the crack has been opened with the saw to make a slot of regular shape. On the drawing board, too, a spline is a thin strip of wood (sometimes of other flexible material) which can be used to draw curved lines such as hull waterlines. In the engineering shop a spline is a raised ridge on a shaft which keys into a corresponding slot on a pinion or other female member. As a verb, you would spline a crack in a hull, and you would have a splined shaft

Split rig

The general term for a sailplan set on more than one mast, such as a ketch or a schooner. This allows the total sail area to be split into smaller, and more easily handled parts. Although a cutter splits her headsail area into two, people do not normally consider her to deserve the term ‘split rig’.

Spoil ground, dumping ground

An area of sea bottom reserved for the dumping of waste of one kind or another. Usually clear of any likely anchorage, and in relatively deep water. Marked on the chart by a surrounding dashed line, and at sea (if at all) by yellow buoys.


Broadly speaking a subsidiary structure extending from the side of the ship. Nowadays most commonly used to describe the inflatable hull sections of a Rigid Inflatable Boat (RIB). The port and starboard floats of a trimaran would also be called sponsons, and when used of small pleasure craft the word normally implies some sort of stabilising float. But in ships a sponson may be a gun platform jutting from the side, or the platforms forward and aft of the paddle-wheels on a steamer so equipped.

Spoon bows

These rise clear of the water and are rounded in their lower sections. They contrast with the wedge-like bows of the old straight-stemmed boats.

Sportsboat rule

Race handicap rule.

Spreader lights

Lights arranged to shine down and illuminate the deck, and especially the region of the foot of the mast, for night work. For convenience they are often mounted on the undersides of the spreaders – hence their name – though similar lights may be fitted directly to the mast itself.


Struts, normally used in pairs to hold the shrouds away from the mast and so widen the angle at which each shroud meets the masthead. The term cross-tree may be applied to a pair of spreaders made in a single continuous unit, but on ships, cross-trees may be quite short arms or brackets whose purpose is simply to form attachment points for various blocks and eyes.


A mooring rope used to restrain fore and aft movement of a boat. Normally, two springs are used, one leading from aft forward, and the other leading from forward aft. Except in the most sheltered waters, a pair of spring is essential when mooring alongside.

Spring tide

These tides occur approximately every fortnight and have a greater range than Neaps. (See also: Tide).

Spring, to

When a plank or other structural component lifts, or springs away from its attachment point it is said to be ‘sprung’. ‘She had several sprung planks, among other damage … ‘ Hence a boat will spring a leak.


A pole or spar, and most commonly the long spar that extends the peak of a four-sided Spritsail. The sprit runs diagonally from the foot of the mast where, in Thames barge jargon, its downward thrust is supported by a wire or chain called the ‘stanliff.

Spun yarn

A small type of cord, similar to mar line but rather coarser. Not much used nowadays but was formerly used for serving warps, and for odd lashings.


A sudden, but relatively short-lived, increase in wind force, often with a change of wind direction, and with rain. A white squall comes with a clear sky; a black squall comes under ominous lowering clouds, and often with rain.

Square rig

The type of rig which uses four-sided sails hanging beneath yards which are suspended from the mast at their midpoints. There is thus an equal area of sail each side of the mast, whereas the ‘fore-and-aft’ rig sets all, or nearly all, the sail to one side of the mast.


An approximately rectangular sail which is set on a Yard so that its centreline coincides with the mast. Other four-sided sails such as the Gaff, Sprit-sail and various Lugs are set entirely or mainly to one side of the mast.

Squat, to squat

Verb: a vessel is said to squat if she runs with her stern depressed. That commonly happens to an auxiliary yacht when driven at maximum engine power. Noun: a squat (in some parts of the country only) is a scissors type of boom Crutch.

SSB – Single Side Band

SSB – Single Side Band radio – a form of long-distance ship-to-ship and ship-to-shore radio communication now increasingly competing with satellite phones.


Small Ships Register


The quality in a vessel that enables her to resist, and to recover from, a heeling force – usually ballast or weight in the keel. Small open boats can be unstable, whereas larger, decked boats nearly always have ample stability. There are two different types of stability: ‘initial stability’ and ‘ultimate stability’. A wide-bottomed vase with a heavy base will have good Initial stability, but a narrow-bottomed vase which is rather top heavy will have low initial stability. But even though the beamy and well-ballasted one will resist being toppled, neither will right itself when once laid flat: neither has ‘ultimate stability’. The toy clown with rounded and weighted base has all the Ultimate stability you could ask for – he always comes back up when knocked down. Yet the clown has low initial stability because it is quite easy to tilt him the fIrst few degrees. He heels more easily than the broad, ballasted vase. Boats may have either kind of stability, or a mixture, depending on their beam, their shape, and their ballast. In ordinary speech a boat with high initial stability is said to be Stiff. The converse is Tender.


A pole or stick used to support an ensign or a burgee. A bigger, stouter pole is a Stave and forms the main part of a Boathook.


A vertical post, usually of metal tube, supporting the guard rail or lifelines which surround the decks. If your boat is big enough to have an awning she may have taller stanchions to support it.

Stand, to

To head the boat in a specifIc direction. You can stand across a bay, or stand into it, and in each of those examples the implication is one of positive motion in a positive direction. But when a vessel Stands off she may lie hove-to or sail around aimlessly, waiting at some distance offshore. And when she Stands on and off, she first stands (ie. sails) towards the shore, and then away from it, but only with the intention of killing time and not with the desire to get anywhere.

Stand-on vessel

Under Rule 17 of the Collision Regulations, when one of two vessels has to keep out of the way of the other, the other ‘shall retain her course and speed’. In other words she stands on. This makes it easy for the give-way vessel to avoid her, whereas if both change course a collision could result. Nevertheless, no vessel is given right of way over other vessels in the Collision Regulations, and in the last resort the stand-on vessel has a responsibility to take avoiding action if that is the only way to avert a disaster.

Standard port

A port for which times and heights of tides have been specially and fully calculated. A Secondary port is one for which tide times are found by applying a ‘difference’ on a standard port.

Standing part

The end of a tackle that is permanently made fast, by contrast with the hauling part.

Standing rigging

The fixed rigging, such as Shrouds and Stays, which supports the mast, bowsprit and so forth. Halyards, sheets and so forth form the Running rigging.

Standing wave

A surface wave which does not move forward. Seen, for example, where a fast-running stream crosses a submerged ledge.

Star crazing

A pattern of fine cracks in the gel coat of a laminated resinglass structure. The cracks usually radiate from a point where an excessive load has deformed the surface, and a sensible owner will clean them out and fill with resin, or perhaps lay on a good paint treatment. If star crazing results from normal loads you will know that the structure is too flexible and you will be wise to back it with extra stiffening.


The vessel’s own right-hand side.

Starboard tack

Sailing with the wind on the starboard side and the mainsail out to port. When two sailing boats meet on crossing courses, the boat on starboard tack has right of way. The International Regulations for Preventing Collisions at Sea lay down that a vessel with her mainsail out to port is on the starboard tack, so the legal definition embraces running as well as reaching.

Start, to

To ease a rope slightly – for example a sheet. (See also: Check)

Starve, to

To sail a boat too close to the wind. Starving and Pinching are almost synonymous.

Station pointer

A pilotage instrument with three arms pivoted on a graduated disc. If the three arms can be aligned with three fixed and identifiable objects the pattern so formed can be transferred to the chart where the focal point of the arms must correspond with the position of the observer. Rarely used nowadays.


The yacht designer divides the hull length into a number of stations, each of which is in effect a plane or cross-section of the hull.


A stave is a stout pole, such as forms the main part of a boathook. A staff is somewhat less robust.

Stave in, to

To make a hole in a hull by knocking, or bursting, a plank inward. The past tense and participle is ‘stove in’.

Stave off, to

To fend off


Usually the forward and after mast supports (forestay, backstay), but not the lateral supports which are called the Shrouds. There is also the Bobstay, leading down from the bowsprit end to the cutwater. But the lateral stays are the ‘bowsprit shrouds’.

Stay, to

To turn through the wind from one tack to the other. If a boat fails to stay she may get in irons.


See also: Headsail.

Steadily (in shipping forecast)

Moving at 15 to 25 knots

Steaming light

The white, forward-showing light carried by a powered vessel by night or in bad visibility. In the Collision Regulations this is called a ‘Masthead Light’ (though not required to be carried at the masthead) and it must show from dead ahead to 22.5 degrees abaft the beam on each side. A vessel of less than fifty metres length may show one such light: those longer must show another similar light farther aft and higher up. A boat under sail does not show a forward white light.


A shore which slopes down steeply into and beneath the water is said to be ‘steep-to’.

Steerage way

A rudder has no effect in still water and no useful effect when a boat is moving very slowly. Steerage way is simply the speed at which any particular vessel becomes controllable in any particular circumstance. Steerage way will be a higher speed in rough water than in smooth, for example.

Steeve, to

Some bowsprits are pivoted so that they can be cocked up to a more or less vertical angle. The sprit is said to be ‘steeved’ or ‘steeved up’


Traditionally a hunk of oak that forms the forward extremity of the hull. In many modern boats it’s a laminate of polyester resin and glass fibres, but it’s still called the stem. There is a difference between the stem and the Bows. The lower part of the stem is the Cutwater, and the hull immediately adjacent to that is the Forefoot.


Stemhead (fitting, roller, etc) – The stemhead is the top of the stem and is normally capped with a metal component which may serve more than one task, commonly to anchor the lower end of the Forestay, and to provide a Fairlead for the anchor cable.


1) A fitting in which the heel of the mast is located. A mast is stepped when it is installed in the boat. Furthermore it may be stepped on deck (often in a Tabernacle) or it may pass through a hole in the deck to be stepped on the keel.

Step (2) A step-shaped break in the bottom line of a high-speed hull which allows the water flow to break away from the hull skin.


The extreme after part of a hull, embracing the Transom or Counter or, in a double-ender, the Stern post, which corresponds to the Stem at the other end.

Stern board

When a sailing boat sails (or drifts) backward she makes a stern board. The manoeuvre is sometimes intentional, but whether intended or not, control can be maintained provided the helmsman appreciates that the rudder will now work in the opposite of its usual sense. (See also: Board.)

Stern drive

A form of transmission between engine and propeller in which a horizontal shaft from the engine passes through the transom to bevel gears which turn a vertical shaft running down outside the hull to a point below the waterline. Here a further set of bevel gears achieves a second right-angle turn to rotate a more or less horizontal propeller shaft. This form of drive allows the engine to be sited well aft in the hull and (usually) allows the ‘drive leg’ with the lower gear housing and the propeller to swing clear out of the water for inspection or repair. Transom drive, and inboard-outboard are other names given to this arrangement but the term ‘Z-Drive’ is the property of a single manufacturer.

Stern gland

A sleeve around the propeller shaft packed with compressible material so as to allow the shaft to turn without admitting water. The packing can be compressed by means of a large nut which also encompasses the shaft.

Stern light

A white light near the stern of a vessel showing from dead astern to 22.5 degrees abaft the beam on either side. Must be shown by both powered and sailing craft. The arc of the stern light is complementary to that of the Steaming light, the two together covering a complete circle.

Stern sheets

The volume in the extreme after part of an open boat – often the region beneath the tiller or beneath the after thwart.

Stern way

Stern way

Making way astern. A sailing boat makes a Stern board, which is usually a shortlived manoeuvre, whereas a powered vessel makes stern way, which usually implies a more deliberate and extended manoeuvre.


Operating in the same way as a bow-thruster but at or near the stern


A metal tube built into the deadwood at the stern of a hull (or embedded in a resinglass moulding) to form a duct through which the propeller shaft can run. The forward end of the sterntube usually embodies the watertight stern gland, and a bearing for the shaft may also be part of the assembly.


A stiff boat is one which does not heel easily. (See also: Stability)


Stability index. A number derived from a yacht’s significant dimensions and its righting-moment curve. A higher number indicates greater stability.


1) The cross-bar of an anchor.

Stock (2) The upper part of a rudder to which the tiller is connected. The lower part is the Blade.

Stockless anchor

A type of anchor that depends on great weight to make it hold. Not often effective on small leisure boats more common on ships where it’s stowed in the hawse pipes


A short box of wood to support and steady a hull ashore. A Shore is a strut from three to six feet long, say, a stool is usually not more than a couple of feet in height, and is made out of planks about two inches thick and a foot wide, forming an open box.

Stop, to

1) To set a sail ‘In stops’, it is furled up and tied around with stops of thin and feeble twine, rotten cotton, or rubber bands. The stops will break when the sheet is pulled and the wind begins to fill the sail. Such a sail is stopped.

Stop, to (2) To pack or pay a split or small hole with putty or some other form of Stopping.


1) A rope bent on to (for example) an anchor chain to hold it temporarily. Might also be a rope bent on to another (Rolling Hitch) to take the load off it while you make some adjustment.

Stopper (2) A device that instantly holds a sheet fast. Known also as jammers or as lock-offs in the USA, these valuable gadgets usually take the form of a lever operated cam which squeezes and grips the rope. They are commonly used with sheets and halyards, allowing several different ropes to be hauled taut by just one winch.

Stopper knot

Any bulky knot which serves the purpose of preventing the passage of a rope through a fairlead or a block, but a Figure-eight knot is the most common among Yachtsmen.


Putty-like compounds which are used to fill minor dents and cracks before painting. Also known as filler.


A wooden dowel inserted between mating pieces of timber to prevent the passage of water. Where two pieces mate, as in the scarf-joint between stempost and keel, a hole is bored across the joint so that half its diameter is in one of the parts and half its diameter in the other. If water enters, the dowel swells and so fills the bore tightly enough to prevent further penetration.


In weather forecasting, implies weather worse than a gale.

Storm cone

Coastguard stations and some other authorities display black storm cones to warn that gale winds (not necessarily Storm winds) are expected. If the point of the cone is upward the gale is expected from the North: if the downward, then from the South.

Storm jib

See also: SpitfIre.


Stuck in harbour due to poor conditions at sea

Stove in

Part of a hull that is broken inward by a force from outside is said to have been stove in. (See also: Stave in)

Stow, to

The nautical term for ‘put away’, meaning safely stored for the conditions likely to be encountered at sea


A narrow sea passage between two lumps of land.


The whole of one plank in a boat’s hull. Even if it has been necessary to use more than one length of wood to stretch the length of the boat, the result is normally considered one strake.


Run ashore, usually accidentally

Stray current corrosion

Occurs when two metals immersed in salt water become accidentally connected electrically causing galvanic corrosion.


In British parlance the rise and fall of the tide gives rise to tidal streams. In the USA these are tidal currents. Can also mean large-scale movements of oceanic water, such as the Gulf Stream

Stream, to

Towing something on a line astern, such as a sea anchor, or heavy warps to slow you down in a storm. Obselete term referring usually to a patent (Walker) log. You ‘stream the log’ when you put the rotator and line into the water. At the end of the passage you ‘hand the log line’, which means that you pull them back on board.


Transverse wooden battens in the bottom of a pulling boat against which the oarsmen can brace their feet.

Strike, to

To lower some item or other – perhaps a burgee, a sail or a topmast. (See also: Send down)


In wooden construction, fore-and-aft members running the length of the hull. Some may be quite light, others (e.g. bilge stringers), quite heavy. A moulded resinglass hull may have light wooden stringers bonded into the laminate for extra stiffness.


A ring of rope, perhaps with an eye for a shackle, which is used to make an attachment to a spar, a barrel or some such.


The strainer that fits over the intake end of the bilge pumping system. May actually be in the form of a metal box with perforated walls, but whatever its shape, its purpose is to keep shavings and other cloggers out of your bilge pump.


Glass fibre boats are built of resin reinforced with glass, and the resin is commonly polyester dissolved in styrene. The styrene is a monomer which, with the help of a catalyst, links (polymerises) the chains of polyester molecules into a three-dimensional structure. This is the curing process. You need enough styrene but not too much, and any little that is left over gives rise to the typical smell of a ‘fibreglass’ boat.

Sugar scoop

A transom that’s extended or hollowed out to incorporate a bathing platform.

Suit of sails

Suit of sails

A boat is equipped with a suit of sails. All her sails may comprise more than one suit and collectively they are her ‘sail wardrobe’. The place where the sails are stowed in their bags is the sail locker! And the owner keeps his shore-going suit in a ‘hanging locker’, not a wardrobe.

Surface tissue

A finely woven cloth of glass fibres which, when laminated with resin, will result in a relatively smooth finish.

Surge, to

To payout, or ease off, a rope a little at a time by letting it slip round a bollard or winch drum.


A technical examination of a vessel’s hull, rigging, or machinery to determine their condition and fitness for service. But a survey is not a valuation.

Swaged end

The old way of making an eye in the end of a wire was to turn it back and splice it. A quicker and easier way is to swage the two parts of the wire together by clamping them in a sleeve of compressed metal. The die which forms and compresses the metal is itself a Swage.


The passage between the Shell of a block and its Sheave, through which the rope must render freely. (See also: Breech)

Swash (or swatch)

A shallow area which does not uncover at low tide but whose presence makes itself known by disturbing the seas on the surface. Its presence may also be revealed by a swashmark, a line of bubbles, foam and debris on the surface of the sea that is rougWy related to the area of the swash below.

Swashway (or swatchway)

A navigable channel through a region of Swashes.

Sway, to

Had a special meaning in the old sailing ships, but is used by yachtsmen for the lifting or lowering of stores, and so forth, with a rope. You may sway your kitbag from deck to quayside, for example. (See also: Fleet, to)


A long oar, often of the kind used for steering or sculling over the stern.


1) A thickening of the Gunwale of a small boat (often by means of an extra bolster of wood) to provide strength for a Rowlock.

Swell (2) A long ponderous undulation of the sea, but whose waves do not break.

Swift, to

To draw tight with a line or lanyard, usually with a transverse pull, as may be done with a line that holds a halyard away from the mast by hauling toward a shroud. If, for example, you have twin backstays you can tighten them both by swifting – that’s to say by drawing them toward each other with a linking lanyard.


A rope used for swifting. The rope linking each capstan bar to the next, so forming a complete ring.

Swig, to

To swig on a rope is to make the end fast around a cleat, say, and gain slack by hauling laterally, then taking up what is gained.

Swing a compass, to

A compass which suffers deviation due to magnetic material in the boat can be checked by swinging. That means to hold the boat approximately at one point, but with her head at successive directions around the horizon. When the boat is brought to rest at each point the bearing of some fIxed point ashore is read from the compass. Since any magnetic material in the boat will have been moved around the compass during this process the deviation it causes on each heading can be noted. These errors can be noted on a Deviation card or they may be plotted as a curve on graph paper.

Swing the lead, to

A slang term meaning to feign sickness so as to escape duty. A seaman who wants to take a sounding will Cast the lead, not swing it.

Swivel (or swivel link)

A connector whose two parts can rotate in relation to each other. Would be inserted in a mooring chain, for example, to avoid an accumulation of twists over a period of months.

Swivel block

A block whose eye is free to swivel.

Syntactic foam

A lightweight fIller consisting of resin mixed with microscopic glass bubbles. (see also: Microspheres)