Dry-dock interval

The dry-dock interval is the maximum time class rules allow between bottom (docking) surveys, the inspections that examine a ship’s underwater hull and appendages out of the water. Within each five-year class period a ship must have two bottom surveys, and the interval between them must not exceed 36 months. One of the two coincides with the special survey. For eligible ships, an underwater inspection in lieu of drydocking (UWILD) by approved divers and ROV may replace one of the two dockings within the cycle, subject to age limits and class approval, which is common on tankers and gas carriers with hard coatings in good condition.