1.1 Hull Markings on Merchant Vessels
The hulls of merchant vessels feature numerous markings indicating crucial details about their safe operation, cargo capacity, and unique features.
These include :
Load Lines or Plimsoll Lines
One of the most important marks on merchant vessels are load lines, also known as Plimsoll lines.
Named after Samuel Plimsoll, a 19th century champion for maritime safety, load lines are positioned amidships on merchant vessels over 24 metres.
The circle with a horizontal line through it is the Summer Water Line, indicating maximum legal load for the ship in different water densities (freshwater, tropical seawater, etc.).
Load lines ensure sufficient freeboard of the vessel when fully loaded for safe navigation.
Draft Marks:
Vertical lines alongside the hull are draft marks, measuring the distance between the keel (bottom) and the waterline. Positioned on both port and starboard sides, these numbers help determine the ship's depth for safe passage through canals and harbours as well as indicating a list due to uneven loading.
Bulbous Bow:
A symbol resembling a tilted "5" often indicates a bulbous bow. This underwater protrusion improves fuel efficiency and reduces wave resistance, making the ship more streamlined.
Bow Thruster :
Look for a circle with an "X" near the bow. This signifies a bow thruster, a powerful propeller that helps the ship manoeuvre sideways, especially useful for docking and tight spaces.
Merchant ships often require the assistance of tugs when manoeuvring in ports or berthing alongside. Some areas of the hull may not be structurally designed to withstand the pressure of a tug in which case they are protected by a « No Tug » marking.
Safe Working Load :
White arrows pointing towards the bitts (mooring posts) indicate the safe working load for pulling or lifting cargo. Exceeding this limit can damage the ship's structure.
Pilot Boarding Mark:
A white rectangle with a yellow border near the bow is the pilot boarding mark. This indicates the safest spot for the pilot to board the ship during navigation.
IMO Number:
Every merchant vessel has a unique IMO number painted on its hull. This 7-digit code serves as a global identifier, crucial for tracking and communication.
Vessel name and port of registration :
Many countries require merchant vessels to display their name and port of registration on the hull at the bow and sometimes at the stern.
This simplifies identification for coast guards and other authorities, aiding in search and rescue or law enforcement situations. It also provides transparency about the vessel's origin for port authorities and other vessels.
