Who cannot go for EDD?

Answer

Under IACS Recommendation No. 133 and the rules of major Classification Societies (e.g., DNV, ABS, ClassNK, IRS), the Extended Dry-Docking (EDD) Scheme—which extends the dry-docking interval from 5 years to 7.5 years by utilizing two consecutive In-Water Surveys—is strictly restricted.

The following ships, technical arrangements, and conditions cannot go for or remain in an EDD scheme:

1. Ineligible Vessel Types

Passenger Ships (due to high human safety risk).
Enhanced Survey Programme (ESP) Ships: This includes Oil Tankers, Chemical Tankers, and Bulk Carriers.
High-Speed Craft (HSC).
Ships subject to special hull survey rules under IACS UR Z7.1.

2. Age & Operational Disqualification Criteria

Ships Over 10 Years Old (at entry): A vessel cannot enter the EDD scheme for the first time if it has already reached 10 years of age.
Mandatory Dis-enrollment at 15 Years: Any ship currently enrolled in an EDD scheme must be automatically dis-enrolled once it reaches 15 years of age, requiring a physical dry-docking.
Change of Ownership, Management, or Flag: The EDD approval is automatically terminated if there is a change in the ship’s owner, technical management company, or Flag State administration.

3. Ineligible Propulsion & Mechanical Arrangements

Keyed Tapered Shafts: Ships where the propeller connection to the tailshaft is by means of a keyed taper (due to the risk of shaft cracking that requires physical draw-out for inspection).
Propulsion Thrusters / Azimuth Thrusters: Ships fitted with dynamic propulsion thrusters, unless specific afloat maintenance and survey arrangements approved by Class are in place.

4. Maintenance, Structural & Survey Non-Compliance

Poor Ballast Tank Coating: Ships where the protective coating in double bottom/double side ballast tanks or void spaces is graded lower than "GOOD" condition.
No Tailshaft Condition Monitoring (TCM): Vessels that lack an approved Tailshaft Condition Monitoring notation / survey arrangement.
Outstanding Structural Damage: Ships with unresolved underwater structural defects, hull deformations, or active Conditions of Class requiring dry-dock repair.
Flag State Disapproval: Ships flying the flag of a maritime administration that does not explicitly accept the EDD scheme.