Answer
In-Water Survey (IWS):
An In-Water Survey is a formal inspection of the underwater body of a ship carried out by an approved diving company using closed-circuit television (CCTV) under the direct supervision of a Classification Society surveyor.
- Requirements:
- Class Notation "IWS" stamped on the vessel.
- High-durability paint coating designed for extended submerged periods.
- Clear hull markings indicating frame numbers, sea chests, transverse bulkheads, and propeller blade numbers.
- Special provisions to measure rudder stock clearances, stern tube wear-down (poker gauge readings), and sea valve blanking arrangements while afloat.
Extended Dry Docking (EDD):
The EDD Scheme permits qualifying general cargo and container vessels (non-ESP ships) to extend the Dry-Docking interval from 5 years up to 7.5 years by substituting the intermediate out-of-water dry docking with an approved In-Water Survey.
- Key Conditions:
- Applicable generally to ships under 15 years of age.
- Requires Flag State approval and Class compliance.
- Enhanced hull protective coatings (specifically silicone/fluoropolymer foul-release systems designed for 7.5 years).
- Fitted with impressed current cathodic protection (ICCP) or extended-life sacrificial anodes.