Maritime Dictionary – Everything that Starts with Letter “I”

by | Last updated Nov 24, 2023 | Maritime Dictionary | 0 comments

I – India. Code flag; I am altering my course to port. Sound signal; I am altering my course to port. Morse Code; ● ●.

I Bar – Flat rolled steel section with small flat flange across longitudinal edges.

Ice – Water that has congealed due to lack of heat. Fresh water freezes at 0°C; salt water at about —3°C. Eleven cubic feet of ice represent 10 cubic feet of water. Owing to heat absorbed by melting ice, the meteorological aspect of ice is important.

Ice Anchor – Single fluke with shank. Put in hole or crack in ice for mooring purposes.

Ice Beam – Baulk of timber fitted to bow of ship, for fending off ice.

Ice Breaker – Power-driven vessel with bow specially shaped to tread down and break sheet ice, and make a navigable lane. 2. Sloping piles on upstream side of a pier to deflect or break up floating ice.

Ice Clause – Inserted in marine contracts, when appropriate, to cover cases in which a ship or port may be ice bound.

Ice Doubling – Additional external planking fitted to vessels engaged in ice bound latitudes.

Ice Fender – ‘Ice Beam.’

Ice Lead – Navigable lane of water through ice.

Ice Master – One who takes charge of navigation of a whaler when in ice.

Ice Patrol – Ships and personnel employed in watching lor ice, and derelicts, in North Atlantic Ocean. Established by International Safety Convention, 1929. Maintained by I. M. O. See SOLAS Chapter V 5 & 6.

Ice Report – Radio report, to shore stations and near-by ships, made by master of any vessel sighting ice. Penalty for not reporting is £50.

Iceberg – Great mass of floating ice that has broken off a glacier and been carried seaward. Waterplane area may be more than five square miles; underwater depth up to 300 fathoms. Movement may be with prevalent wind or current, but may be due to deep current. Generally advisable to pass to windward of it. Ice Blink. See ‘Blink’

Icebound – Said of a ship when she cannot move because of surrounding ice. Said of a port when it is inaccessible because of ice.

Icelandic Lows – Meteorological depressions that frequently form over Iceland.

Idler – Member of a crew who works all day but does not keep night watches; e. g. carpenter, sailmaker. Termed ‘dayman’ in R. N.

‘If Sufficient Water’  Clause inserted in a charter party to qualify the obligation to discharge in a named dock, or berth, if there be not sufficient depth of water when the order to berth is given.

Ignition Point – Minimum temperature at which a substance will ignite and burn. Is always higher than ‘Flash point’.

Ikara – An anti-submarine missile delivering a homing torpedo.

Immediately Dangerous to Life, Health (I.D.L.H.) – An atmosphere that poses an immediate threat to life, would cause irreversible adverse health effects, or would impair an individual’s ability to escape from a dangerous atmosphere.

Immersion – The sinking of a substance into a fluid. Immersion Suit. Life saving equipment required by SOLAS Chapter III 33.

Immigration Regulations – Laws and rules regulating the entry of aliens into a country.

Impedance – Circuit resistance to an alternating current when caused by self-inductance, circuit capacity and ohmic resistance.

Implied Warranties – Assurances that are not made specifically by an insurer but are implied by his application for insurance. These are, that the ship is seaworthy; that the venture is lawful: that the venture will be carried out in a lawful manner.

Import – To bring into a country, from abroad.

Imports – Goods brought into a country from another country.

Impulse – Force applied to cause movement.

In Ballast – Said of a vessel when she is not carrying cargo.

In Haul – Any rope acting in a direction opposite to that of an outhaul. Particularly applied to rope or purchase by which a jib boom, studdingsail yard, or other spar, is hauled inboard.

In Irons – Losing momentum while tacking a vessel through the eye of the wind, the vessel can be temporarily immobilised with the sails stalled. She will have to fall off the wind, get the sails full again and with speed on once more attempt to use her forward momentum to swing through the wind.

In Stays – A sailing vessels position between tacks, when she is headed into the wind.

In Stops – A flag or sail furled and secured with a weak thread or loose hitch so it can be released by a sharp pull.

Inboard – Inside a ship. That end, or part, of anything that is nearer to the ship’s fore and aft line than is the other end or part.

Inboard-outboard – A propulsion system with the motor mounted near the stern, coupled by a shaft to an external outboard drive unit. The components of this unit are similar to those of an outboard engine drive, having forward and reverse gears, a vertical shaft, and a propeller shaft.

Incertfa – A SAR uncertainty phase requiring monitoring and intelligence gathering for more task information.

Inch Trim Moment – Moment of force required to change trim of vessel by one inch. Now more usually M. C. T. 1cm. Moment to change trim 1 centimetre.

‘Inchmaree’ Clause – Clause, in a policy of marine insurance to cover damage or loss to ship when caused by latent defect not discoverable by due diligence.

Inclination – Leaning. The mutual leaning of two planes, or lines, towards each other. The angular intersection of two planes or lines.

Inclination of Ecliptic – Angular intersection of plane of Equinoctial by plane of Ecliptic. Value is 23° 27′.

Inclination of Needle – Angle of magnetic dip. Angle that a magnetic needle will make with the sensible horizon when freely suspended in the vertical plane.

Inclination of Orbit – Angular intersection of Ecliptic by the orbital plane of a heavenly body.

Inclination of Ship – Angle of list, or thwartship deviation from the vertical, of a line perpendicular to the deck of a vessel.

Inclining Experiment – ‘Heeling experiment.’

Inclinometer – A weighted pointer that indicates the degrees of list/heel of a vessel.

Increment – Quantity, usually variable, that is added to an independent variable in an invariable expression. When very small it is termed a ‘differential’.

Indenture – Sealed and binding agreement entered into by two parties. Particularly applied to agreement between ship owner or master, and parent and guardian of a minor apprenticed to sea service.

Independent Piece – Beak-shaped projection from a vessel’s stem under the bowsprit.

Index – That which points out, or indicates. Of a logarithm, is the integral number that precedes the mantissa.

Index Bar – Radial arm moving over a sextant, and carrying index glass and vernier.

Index Correction – Quantity to be applied to an incorrect indication to convert it to a correct value.

Index Error – Difference between a true value and a value indicated. Small but persistent sextant error when reading the scale of the angle of arc, needing correction for being either on arc (too high) or off arc (too low).

Index Glass – Pivoted mirror on index bar of sextant.

Index Mirror – Alternative name for an index glass.

Indiaman – Name formerly given to any large ship regularly trading to India.

Indian Spring Low Water – Datum used in Indian tides.

Indicated Air Speed (I.A.S.) – The aircraft speed shown on the air speed indicator gauge. IAS corrected for instrument error and atmospheric density is equal to true air speed.

Indicated Horse Power – Measurement of power developed in cylinder of a reciprocating engine as deduced from an indicator diagram.

Indicator – Any instrument that indicates mechanically. Especially applied to instrument that graphically indicates work done by steam while in a cylinder of a reciprocating engine.

Indicator Diagram – Graph of work done by steam while in a cylinder. Produced by mechanism incorporated in an ‘Indicator’.

Indorsement. Endorsement – That which is written on the back of a document.

Induced Current Current developed in a conductor that is near another conductor carrying an alternating or fluctuating current. 2. Current passing through a conductor that is in the field of moving magnet.

Induced Draught – Artificial draught through a furnace caused by expediting exhaust of funnel gases; so causing a partial vacuum on escape end of furnace and stimulating flow of air to furnace.

Induced Magnetism – Magnetism, of a ferrous substance, due to proximity of a magnet or magnetic field.

Inducement – Selecting a port of call on the basis of cargo earning potential justifying the routing costs.

Induction – Generation of an effect by the action of a distant cause.

Indulgence Passenger – Person given a passage in one of H. M. ships; usually on compassionate grounds.

Inert Gas – A gas with limited re-activeness such as carbon dioxide, argon, helium or nitrogen.

Inert Gas System – The prevention of explosion in tankers by replacing the cargo on pump out with an Inert Gas, often the exhaust of the ship’s engine.

Inertial Navigation – A highly-refined system of Dead Reckoning navigation. Accelerometers, or doppler techniques, and a computer measure the distance travelled from the original departure position.

Inferior Conjunction – Conjunction of Moon or planet occurring between Earth and Sun.

Inferior Meridian – That meridian 180° distant from a given meridian.

Inferior Planet – Either Venus or Mercury, whose orbits around Sun lie inside orbit of Earth.

Inflammable Liquids – Also named flammable liquids – liable to spontaneous combustion which gives off flammable vapours at or below 80 degrees F. For example, ether, ethyl, benzene, gasoline, paints, enamels, etc.

Inflatable Liferaft – Triggered manually or automatically if the ship sinks. These inflatables have hoods to protect survivors and food and equipment according to the type of voyage undertaken. SOLAS Chapter III 68 & 69.

Ingress – A means or place of going in.

Inherent Vice – Inseparable property of a substance whereby it damages or destroys itself.

Initial Condensation – Conversion of a certain amount of steam into water as it enters a cylinder. Due to temperature of cylinder being less than temperature of steam.

Initial Position Error – The estimated probable error of the initially reported position of a SAR incident.

Initial Stability – Resistance offered by a vessel, when floating upright, to forces tending to list her.

Injection – Forcing of fuel into cylinder of a compression ignition oil engine. Forcing of feed water into a boiler.

Inland Navigation – Transportation limited to canals, rivers or lakes.

Inland Waters – Defined by NSCV Part D as non-tidal waters that are open to the public for navigation.

Innage – An un-common term for tank capacity (depth of liquid) being the opposite from ullage.

Innavigable – Not navigable by ships.

Inner Bottom – Plating laid on top of floors. Upper plating of double bottom tanks. Deck resting on upper sides of floor timbers.

Inner Jib – The third foresail set on a sailing ship inside the outer jib and middle staysail.

Inner Post – Timber secured to fore side of stern post to take seatings of transom.

Inner Shell – A surface inside the vessels outer shell for the purpose of increased watertightness in the case of exterior plate damage.

Inner Turns – Those turns, of earing of a square sail, that confine the sail against the yard.

Inshore – Near to the shore. On the shoreward side.

Inshore – The coastal waters where most small craft operate, or close to the coastline. In Australian Domestic regulations defined as within 15 nautical miles of shore.

Inshore Traffic Zone – A routeing area between a traffic separation zone and the coast reserved for smaller vessels and those that are not through traffic.

Inside Clinch – Name given to end of rope that is formed into a loop by taking a round turn on standing part with end on inside of loop.

Insolation – Sun’s radiation as received at surface of Earth.

Inspection – Visual examination. 2. Entering a table with known data and abstracting a tabulated resultant. In Stays. The position of a sailing vessel when she is going from one tack to the other, head to wind.

Institute Clauses – Standard forms of clauses that may be inserted in a policy of marine insurance to limit it, or to extend its scope. Framed and sanctioned by the Institute of London underwriters. They cover practically all contingencies and requirements.

Institute of London Underwriters – Organisation of firms and persons undertaking marine insurance. Founded 1884.

Instrument Meteorological Conditions (IMC) – expressed in terms of visibility, distance from cloud, and ceiling less than the minima specified for visual meteorological conditions.

Instrumental Error – Error in a measured quantity when due to defect or limitation in the measuring instrument.

Insulating Coat – Coating of paint, or other substance, to protect a plate or fitting from deterioration by a subsequent coating. Particularly applied to bitumastic coat between ship’s bottom plating and a corrosive anti-fouling paint.

Insulation – Prevention of leakage from, or into, a body or substance. 2. As a noun or adjective. The glass fibre, cork, wood or other construction which prevents the passage of heat. Hence Insulated Ship, Insulated Container.

Insulator – An electrical insulator is a material which will not carry electric current. Plastics, rubber, glass, and dry air are examples.

Insurable Interest – Such interest in a ship or voyage that failure of ship to carry out voyage as intended would entail financial loss.

Insurable Value – Sum of money for which insurable items may lawfully and reasonably be insured. In case of goods carried by sea it is made up of invoiced cost of goods, cost of freight, cost of insurance, profit. Profit usually assessed as 10 per cent of other costs.

Insurance Broker – Person who acts as intermediary between those requiring insurance and those willing to insure; more especially those who place marine risks with underwriters.

Insurance Clubs – ‘Mutual Indemnity Associations.’ ‘Small Damage Clubs.’

Insurance Policy – Signed contract of an insurer to make good a loss against which insurance has been effected.

Insurer/s – Person/s who have contracted to make good a maritime loss.

Intake – Specific amount taken into ship as cargo.

Intake Manifold – A casting for distributing fuel and air supply to the intake ports of a petrol engine.

Intake Measurement – Actual measurement, by weight or volume, of cargo taken into a vessel.

Intake Rose – A grid attached to the vessel’s hull which covers the inlet for sea water into the cooling systems.

Integrated Tow – Multiple box shaped barges joined head to toe.

Integrated Tug Barge – A barge pushed by a tugboat joined to it.

Intercalary Day – 29th February. Inserted every, fourth year, with exceptions, to keep the Civil year in step with the Tropical year.

Intercardinal Points – Those points halfway between the cardinal points of a compass.

Intercept – Distance between the CP and a point through which the true position line runs.

Intercept Method – Alternative name for ‘Marc St. Hilaire Method’.

Intercostal – A term applying to longitudinals, beams, girders or stiffeners constituted from short lengths between frame to frame or beam to beam.

Intercostal Centre Keelson – Internal keel that is stopped at each floor but extends the full length along centre line of the keel.

Intercostal Plates – Lengths of plating that go fore and aft between frames.

Interest Policy – Contract of insurance covering some special interest or parcel of cargo. Also applied to valid policies to distinguish them from ‘Honour’ or ‘No interest’ policies.

Interfacing – Connecting electronic navigation aids so that information is shared between them.

Interior Planets – Inferior planets. Those whose orbits lie within that of Earth.

Intermodal – Cargo movement by interchangeable but compatible transport equipment by air, sea and land.

Internal Combustion Engine – Engine that operates through fuel being consumed in itself.

International Aeronautical and Maritime Search and Rescue (IAMSAR) – The IMO convention for  that replaces the SAR convention and Mersar manual.

International Code of Signals – System of flag and Morse signals that superseded the ‘Commercial Code’. Last revised 1969.

International Convention – Meeting of representatives of maritime nations to formulate rules concerning shipping.

International Load Line Ship – Any vessel of 150 tons (gross), or over, that carries cargo or passengers, and thus comes under the International Load Line Rules. Ships of war, fishing boats and most yachts are exempt.

International Maritime Dangerous Goods Code (IMDG) – an IMO Convention to assist in safe carriage of dangerous cargos.

International Maritime Satellite Organisation (INMARSAT) – A system of geostationary satellites for worldwide mobile communication services, and which support the Global Maritime Distress and Safety System (GMDSS)and other emergency communications systems.

International Nautical Mile – Unit adopted by the International Hydrographic Bureau and having a value of 1852 metres. This length—6076 ft. 2 in.—is equivalent to one minute of latitude in Lat. 44 1/2°.

International Rating Rules – Rules for measurement of yachts of 14 1/2 metres (L. W. L. 47 1/2 ft.) and under. Adopted in Europe, 1933.

International Safety Management Code (ISM Code) – The IMO Assembly adopted the in 1993 that implements international standards for the safe management of ships.

International Ship and Port Facility Security Code (ISPS Code) – is an amendment to the Safety of Life at Sea (SOLAS) Convention for minimum security arrangements for ships, ports and government agencies.

Interpolation – Determination of value of a quantity intermediate between two quantities whose values are given.

Interrupted Quick Flashing – Name given to a quick flashing light that is eclipsed at regular intervals.

Intertidal – Between the high and low water.

Interval – Time value of difference between any two epochs. Distance between any two points. Arithmetical value of difference between any two given arithmetical quantities.

Intracoastal Waterway ICW – bays, rivers, and canals along the coasts (such as the Atlantic and Gulf of Mexico coasts), connected so that vessels may travel without going into the sea.

Intrinsic Energy – Of steam, is the amount of heat energy available for work at the point of application.

Inversion – Used in meteorology to denote that temperature increases with height above surface of Earth. In tides, is a rise in water level with a rise in barometric pressure.

Invertebrate – An animal without a backbone.

Inverted Tide – Occurrence of low water at the same time as Moon’s transit at the place.

Invoice – Document sent by shipper to Customs authorities. States nature, quantity and value of goods shipped.

Inwale – Name sometimes given to the internal fore and aft stiffener running along inboard side of upper strake of a boat. More usually called ‘gunwale’.

Inward Clearing Bill – Document issued by Customs authorities when ship has been searched for unentered goods, stores checked and formalities complied with.

Iridium – Extremely hard metal used for compass pivots.

Irish Pendant – Nickname for a rope end, or yarn stop, blowing about in a wind. More correctly, is any flag, pendant or ensign with a frayed fly.

Iroko – African straight grained hardwood timber durable for marine use. Unpleasant and acrid sawdust in processing.

Iron Bark – Australian eucalypt timber suitable for marine sheathing for abrasion protection.

Iron Wire Rope – Non-flexible rope made of small iron wires and no hearts. Used for standing rigging and other purposes in which extension due to stress cannot be tolerated.

Ironbound – Said of shore having rocky cliffs and no safe landing place.

Ironclad – Early name for warships whose wooden sides were sheathed with iron. Name persisted after hulls were entirely of steel.

Irradiation – Apparent increase in size of a heavenly body caused by the brightness of its light.

Isallobar – Line, on a meteorological chart, passing through all positions at which pressure changes were similar during a given period.

Isallobaric Wind – Wind component that is due to changing pressure gradients.

Isaz – Short name for a line of iso-azimuth.

Isentropic – Adiabatic.

Isherwood System – Shipbuilding method in which continuous longitudinal framing is the dominant feature.

Iso – Prefix meaning ‘equal’.

Iso-Azimuth – Equal, or similar, in azimuth.

Isobar – Line, on a meteorological chart, passing through all places having equal barometric pressure.

Isobath – Line, on a chart, passing through points having equal depth.

Isoclinic Line – Line passing through all positions on Earth that have the same value of magnetic dip.

Isodynamic Line – Line passing through all places on Earth having the same value of magnetic force.

Isogonal, Isogonic, Line – Line drawn through all positions on Earth having the equal magnetic variation.

Isohel – Line, on meteorological chart, passing through all places having the same period of sunshine.

Isohyet – Line, on meteorological chart, passing through all places having the same amount of rainfall.

Isometric Drawing – A perspective drawing method where all lines are drawn to their true scale length using a common angle for diagonals, with no vanishing point, but simulating a three dimensional view.

Isoneph – Line, on a meteorological chart, passing through all positions having the same amount of cloud.

Isophase – Flashing light of equal light and dark periods.

Isotherm – Line, on a meteorological chart, passing through all positions having the same temperature.

Isotherm – Points of equal temperature.

Isothermal Expansion – Expansion of gas, or steam, without an accompanying reduction of temperature. This necessitates an intake of heat during expansion.

Isothermal Line – An isotherm.

Isthmus – A neck of land joining two larger areas of land.Ivory’s Rule – Method of solving the ‘latitude of double altitude’ problem; the PZX triangle being divided into right-angled spherical triangles.



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