Maritime Terminology: Essential Ship Communication

Shipboard Positions and Communication

Forward Station: Chief Officer’s position towards the head of the ship.

Aft Station: Second Officer’s position towards the stern of the ship.

Bridge: Captain’s position.

Read: “How do you read me?” The captain is asking about the quality of reception.

Signal Strength: The strength of the signal reception.

Starboard Quarter: The starboard side aft of the bridge.

Mooring and Docking Terminology

Berth: A sea room to be kept for. It can be a place in an anchoring area/anchorage or a place to moor.

Take To: “Take… to capstan…” Bring a line to the capstan, so that when the capstan is started, the line can be hauled on board the ship.

Capstan: Mechanical barrel around which lines and wires are turned.

Make Fast: “… and make fast.” Take a line to the bitts so that it will hold weight (or pull) without slipping. Usually, a rope or wire is turned up on bitts to make it fast.

Single Up (to): “Single up forward/aft.” Instruction to haul or pull on board all but essential lines mentioned, so that the ship is ready to leave the quay or berth. “I will single up forward/aft.” Confirmation of order; “I am singled up forward/aft.” The operation has been completed.

Let Go: “Let go fore and aft.” Cast off all lines (unless a specific line is mentioned, in which case that line only).

Fore and Aft: Forward and Aft.

Lines:

• Head Line – Forward/Aft
• Spring – Forward/Aft
• Breast Line – Forward/Aft
• Stern Line
• Buoy Line – Forward/Aft
• Towing Line

Mooring lines: Head Line – Forward/Aft Spring – Forward/Aft Breast Line – Stern Line

Vessel Dimensions and Clearances

Depth: Height in meters from the uppermost continuous deck to the vessel’s bottom.

Freeboard: Height in meters from the water level to the uppermost continuous deck, on most vessels. This is essential information for the safety of the vessel, and also for pilots and port officials wishing to board. If the freeboard is too high, it may be difficult, dangerous, or impossible to board the vessel from a launch. Other means, such as a helicopter, will then have to be employed.

Draught: Maximum depth from the waterline to the vessel’s bottom, expressed in meters. It is the limiting factor for the size of the vessel that can be berthed in most harbors. It is normally given for saltwater of specific gravity 1.025.

Air Draught / Air Draft: Height in meters from the water level to the highest point of the vessel. This is essential information for safe passage under bridges, and also for loading at installations such as container terminals, bulk loading conveyors, etc.

Height: Height in meters from the highest point of the vessel to the vessel’s bottom.

Underbridge Clearance: Distance in meters from the highest point of the vessel to the bridge.

Underkeel Clearance: Depth remaining under a vessel’s bottom. Particularly for large vessels in shallow water, this is essential information because of “squat”.

In some busy channels, squat can reduce under-keel clearance from a safe amount to zero. Therefore, captains will wish to know what their under-keel clearance will be and adjust their speed accordingly before proceeding into shallow water.

Squat: It is the change in trim when proceeding in shallow water at more than 5 knots. It increases the draught. The ship can be trimmed by the head or by the stern. She is not on an even keel. El barco puede estar aproado o apopado. No está con calados parejos

Sinkage: It is the depression produced around the hull when proceeding in shallow water at more than 5 knots. It does not affect the draught but reduces the underkeel clearance.