Answer
| Point | Underwater Examination (UWE) | In-Water Survey (IWS) |
|---|---|---|
| Meaning | General inspection/examination of underwater parts of hull while ship is afloat | A formal Class survey carried out underwater in lieu of docking survey, when permitted |
| Purpose | Check underwater condition, damage, fouling, propeller, rudder, sea chests, etc. | Satisfy part/all of the periodical docking survey requirement without dry-docking |
| Class approval required? | Depends on purpose; may simply be an examination ordered after damage/grounding | Yes. Vessel and survey arrangements must comply with Class requirements |
| Substitute for dry dock? | Not necessarily | Yes, when specifically accepted by Class |
| Who carries it out? | Diver/ROV, often under Class/owner supervision depending on purpose | Approved diving company / diver or ROV under Class surveyor’s control/attendance |
| Vessel notation | Not normally required merely for a UWE | Some societies give an IWS notation when vessel is specially approved for in-water surveys |
| Result | Condition report / damage assessment | Counts toward the applicable Class docking survey, subject to satisfactory findings |