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Surveying a ship alongside means sharing the berth with cranes, trucks and cargo gangs. A good plan makes the survey fit into that rhythm instead of fighting it.
We usually dive on the offshore side first and move to the quay side when cargo operations allow, because lowered hooks and loose lashing gear are a real risk to a Diver. The dive supervisor speaks directly with the terminal foreman and the chief officer by radio, and the diving flag is displayed. If cargo work has to stop for a short period, we ask for it early and keep it as short as we can.
Visibility in a busy port is often limited by silt, runoff and the wash from passing vessels. Fenders, mooring lines and the ship's Draft all restrict where the Diver can swim. We check the lines before entry. CCTV lights make up for poor visibility, though in very murky water the surveyor may ask for close-up checks instead of wide views.
Before anyone enters the water, the propeller is locked, the thrusters are isolated and overboard discharges are stopped where possible. Sea water intakes are noted so the engine room does not start pumps near the divers. Our supervisor keeps a written log and can call off the dive at any time. A standby Diver is always dressed and ready.
Class societies accept an in-water survey as a formal part of the bottom inspection when it is carried out under their requirements. Our output is video, photographs, a Thickness Measurement table and written findings. When the surveyor is on deck, he can discuss the findings with us at the end of the dive and tell the master what he needs for the class record.
Most ships need one working day. If the berth is tight or visibility is poor, we plan two shorter sessions at slack water. We tell the agent the expected finish time as soon as the dive plan is agreed, so cargo planning can move around it.
Most problems at the berth come from poor communication. We agree one contact at the terminal, one at the agent and one on the ship's bridge. The dive supervisor tells them when the divers are going in, when they are out and when the work is complete. The chief officer knows which side of the Hull is being worked and when the cranes may start again.
Cargo operations can overrun, fenders can get in the way, or a passing vessel can stir up silt. Occasionally a rope or net is found near the propeller, and the plan changes to deal with it first. We build some margin into the plan and keep the agent informed. If a survey cannot be finished in one session, we report what was completed and arrange the rest.
Q1. How long does an alongside in-water survey take?
Most ships need about 1 working day of 8 to 10 hours. Large ships or poor visibility may need 2 shorter sessions at slack water.
Q2. What is the maximum diving depth for surface-supplied air?
Industry guidance for surface-supplied air diving sets a maximum of 50 m. Hull surveys alongside in Nagoya Port are normally well under 20 m.
Q3. Is a standby Diver always required?
Yes. A standby Diver is dressed and ready at the surface for the whole dive, in addition to the working divers and the supervisor.
Q4. What must the ship isolate before the dive starts?
The propeller must be locked, bow and stern thrusters isolated, and overboard discharges stopped where possible. The chief engineer confirms this before any Diver enters the water.
