Definition
Class societies write rules for hull structure, machinery, electrical and safety systems, approve the drawings, attend construction, and then survey the ship through her life — annual, intermediate and special (renewal) surveys. A ship that keeps to the rules stays "in class", which insurers, charterers and banks require. Most flags also authorise class societies to survey and certify on their behalf under the conventions.
The International Association of Classification Societies (IACS) has 12 member societies, which between them class more than 90% of the world's cargo-carrying tonnage. IACS develops unified requirements and interpretations that its members apply in their rules.[1]
For the buyer, class shows up in the spares: items such as chains, wire ropes, valves on class-relevant systems and certain machinery parts must come with a class certificate or a maker's certificate acceptable to class. State the class society and certificate type on the requisition — a cheaper part without it may not be fitted.
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Sources
- [1] IACS — About us — https://iacs.org.uk/about-us
A working definition for buyers, not legal advice — the contract, the convention text and your club or class have the last word.