In-water survey in lieu of drydocking

An in-water survey is an examination of the outside of the ship’s bottom and related items carried out afloat, accepted by a classification society as an alternative to the periodical bottom survey in drydock. IACS UR Z3 paragraph 1.3 permits it to be considered as an alternative, subject to the conditions at Z3.3.

The governing constraint is evidential: the survey must provide the information normally obtained from a docking survey. Rudder bearing and oil stern bearing clearances require special consideration based on the ship’s operating history, on board testing and stern oil sample reports, because those are the measurements a diver cannot take directly. Special consideration applies to ships of 15 years and over, and for ships under the Enhanced Survey Programme of 15 years of age and above the examination is to be carried out in drydock.

The procedural requirement that is most often overlooked is the service supplier approval. Under UR Z3 paragraph 3.3.4 the survey is carried out under the surveillance of a class surveyor by an in-water survey firm approved as a service supplier under IACS UR Z17, using divers or a remotely operated vehicle. An unapproved diving contractor cannot produce a creditable survey however good the video is. The full article will cover the approval regime, the survey scope, the hull cleanliness and visibility prerequisites, and the interaction with the UR Z3 two-examinations-in-five-years rule.