Glossary
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TermDefinition
- General Nautical Terminology, Weather (Meteorology) Irish Sea
Sea area of the Met Office Shipping Forecast. Covers the Irish Sea between Ireland and Great Britain.
Between Ireland and Great Britain, the...
More Details - General Nautical Terminology IRPCS
- Organisation ISAF
World Sailing, formerly known as the International Sailing Federation (ISAF), is the governing body for the sport of sailing...
More Details - Light Characteristic Iso
A light where the duration of light and darkness are equal.
Isophase describes a navigational aid that emits a light signal with equal periods...
More Details - General Nautical Terminology IsobarOn a synoptic chart, a line joining points of equal pressure
- General Nautical Terminology Isolated Danger Mark
Buoy or pillar positioned on a dangerous underwater obstruction.

An isolated danger mark is a navigation aid used at sea to indicate a...
More Details - Light Characteristic Isophase (Iso)
A light where the duration of light and darkness are equal.
Isophase describes a navigational aid that emits a light signal with equal periods...
More Details - Organisation, Signals & Communication ITU
A specialised agency of the United Nations responsible for coordinating global telecommunication operations and services, including radio...
More Details - General Nautical Terminology, Safety Jackstay
A length of webbing (or on rare occasions a length of wire) which run from the bow to the stern of the vessel. They have sufficient slack in them...
More Details - Flag / Pennant, Signals & Communication Code Flag Juliett (J)

The International Maritime Signal Flag Juliett.
Meaning
I am on fire and have dangerous cargo on board: keep well clear of me.
More Details
OR
I am... - General Nautical Terminology Jib
A triangular sail set ahead of the foremast, typically attached to a stay, and used to improve a vessel's manoeuvrability and balance.
The jib...
More Details - General Nautical Terminology Jib SheetsLines attached to clew of headsail to control sail shape.
- Flag Semaphore, Signals & Communication Letter J (Flag Semaphore)

This signal is also used to transition from letters to numbers when communicating a message.
- Morse Code, Signals & Communication Letter J (Morse Code)
International Morse Code sequence representing the letter J.
- General Nautical Terminology, Safety Jonbuoy
A specialised man overboard recovery device designed to provide buoyancy and visibility to a person in the water.

A Jonbuoy is a...
More Details - Did you know?, Phonetic Alphabet, Signals & Communication Juliett
Pronounced: JOO-lee-ETT
The term for the letter J in the NATO Phonetic Alphabet.
More Details - General Nautical Terminology Jury RigA temporary but effective device that replaces lost or damaged gear
- General Nautical Terminology, Weather (Meteorology) Katabatic Wind
A gravity-driven wind that flows downhill from elevated terrain, such as glaciers or high coastal cliffs, typically bringing colder, denser air...
More Details - Flag / Pennant, Signals & Communication Code Flag Kilo (K)

The International Maritime Signal Flag Kilo.
Meaning
I wish to communicate with you.
More Details
If appended by a Numeral Pennant:
I wish to... - General Nautical Terminology KedgeA technique for moving or turning a ship by using a relatively light anchor known as a kedge.

