Answer
A Class Notation is a standardized alphanumeric code and symbol sequence assigned by a Classification Society (such as DNV, Lloyd's Register, ABS, or Indian Register of Shipping) to a vessel. It officially certifies that the ship’s hull, machinery, equipment, and operational systems meet specific structural, safety, and technical design rules established by that society.
There is no single fixed number of class notations globally. Because each Recognized Organization (RO) maintains its own rulebook independently under IACS guidelines, there are hundreds of distinct notations across various classification societies, categorized into several primary groups.
Class notations are categorized into four primary types:
1. Main Class Notations (Construction & Machinery Base)These fundamental symbols indicate that the vessel’s hull and essential machinery were built under classification supervision and comply with the society’s core rules.
Hull Class Notation: Confirms the structural strength meets the rules for sea-going service (e.g., 100A1 or 1A1).
Machinery Class Notation: Confirms main propulsion engines, boilers, essential auxiliaries, and steering gear meet safety and reliability standards (e.g., LMC for Lloyd's Register, AMS for ABS, or MC for DNV).
These define the specific commercial purpose or cargo-handling design of the vessel. A ship cannot carry specialized cargoes unless its notation reflects compliance with relevant structural and safety rules.
Ship Type Marks:
Oil Tanker,Chemical Tanker Type II,Bulk Carrier,Container Ship,LNG Carrier,Ore Carrier.Enhanced Survey Program (ESP): Mandatory notation for bulk carriers and oil tankers subject to intensive structural thickness measurements and surveys under the IACS ESP Code.
Common Structural Rules (CSR): Indicates double-hull oil tankers (Greater than150 m) or bulk carriers (Greater than 90 m) built according to unified IACS structural strength standards.
These specify operational automation levels, particularly regarding engine room manning.
Unattended Machinery Space (UMS / E0 / AUT-UMS): Certifies that the engine room is fitted with centralized monitoring, automatic safety shutdowns, and fire-detection systems, allowing safely unmanned operation for up to 24 hours.
Dynamic Positioning (DP): Indicates the vessel's capability to maintain position automatically using thrusters.
DP-1/DPS 1: Manual backup required.DP-2/DPS 2: Redundant components (no single failure causes loss of positioning).DP-3/DPS 3: Redundant components separated by A-60 fire divisions and watertight bulkheads.
These optional or specialized notations demonstrate enhanced environmental compliance, operational capability, or safety standards.
Ice Class & Polar Class Notations: Indicates structural hull strengthening and machinery suitability for navigation in ice-infested waters (e.g.,
Ice Class 1A,FS-Ice Class IA Super, or IACS Polar ClassesPC1toPC7).Environmental & Green Notations: Indicates compliance with voluntary low-emission, ballast water, or recycling standards beyond basic MARPOL regulations (e.g.,
CLEAN DESIGN,GREEN PASSPORT,ECO).Cyber Security Notations: Mandated for newbuilds built under IACS UR E26/E27 rules (e.g.,
Cyber Secure Essential[DNV],Cyber Resilience[LR]).
Anatomy of an Example Notation String
A typical classification certificate displays a composite notation string combining these categories:
✠ 100 A1, Double Hull Oil Tanker, CSR, ESP, ✠ LMC, UMS
- ✠ 100 A1: Vessel built under class supervision meeting full hull construction requirements.
- Double Hull Oil Tanker: Specific cargo service capability and hull design.
- CSR & ESP: Built to IACS Common Structural Rules and subject to the Enhanced Survey Programme.
- ✠ LMC: Main and auxiliary machinery surveyed and certified under class rules.
- UMS: Automated engine room approved for periodic unattended operations (central to ECR alarm monitoring and safety interlocks).