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Some parts of a ship's underwater body are hard to see even for a Diver working at arm's length. CCTV inspections in Nagoya Port deal with exactly those places: tunnels, recesses, grated openings and the narrow space behind the rudder.
The bow thruster tunnel is the best-known example. It can be 1.5 to 2.5 m across and several metres long, and the Diver cannot always fit inside it. Sea chests sit behind gratings with narrow bars. The gap between the rudder and the stern frame is tight and often dark. Cooling water intakes and stabiliser recesses are similar. In each case, a camera can reach what a human cannot, and it shows the result to the surveyor at the same moment.
We use three methods. A Diver can hold a small camera close to the opening. An extension pole lets him push the lens deeper without entering. For longer tunnels, a compact ROV can travel inside on a tether, provided the current is low and the opening is free of ropes. We decide the method on the day, after the Diver has checked the opening and the conditions. The report states which camera was used for each area.
Typical findings include loose or missing grating bars, damage to thruster blades, rope or fishing line wrapped around moving parts, and debris sucked into an intake. A small crack near a weld can be hard to spot with a flashlight and easy to see in a clear close-up. Finding these early may prevent a thruster failure at a critical moment, such as berthing in strong wind. That is a better day than finding the problem alongside with a pilot on board.
Every inspection is recorded with a time stamp and the ship's name. We cut the footage into short clips, one for each area, and add notes on position and condition. Photographs are taken from the video and from separate stills. The full recording stays available if the surveyor or technical manager wants to check something later. The report normally reaches you within 24 hours of finishing the work.
CCTV inspections fit into a class survey, but many owners order them separately to check a thruster after a near-miss or before a long voyage. Our team holds ClassNK and ABS certification, so the results are presented in a form class surveyors know. Please tell us in advance which areas you want to see, the type of thruster and any known trouble, so we bring the right camera and lights.
Every camera method has limits, and we explain them before the job. A tether restricts how far an ROV can travel. A pole camera reaches only as far as the pole. Strong current or poor visibility may reduce what we can show. If a tunnel is blocked or too narrow, we report that honestly and suggest another way, such as an internal inspection by the crew with a light, to complete the picture.
Q1. What size is a typical bow thruster tunnel on a bulk carrier?
Tunnel diameters of 1.5 to 2.5 m are common on large bulk carriers, and the tunnel length is often several metres. Smaller ships have smaller tunnels.
Q2. When is an ROV used instead of a Diver camera?
An ROV is considered for long or narrow openings, such as thruster tunnels, when current is low (below about 1 knot) and no ropes or lines are near the opening.
Q3. How long does a CCTV inspection of one thruster take?
Normally 30 to 60 minutes per thruster, including setup, recording and a short review with the surveyor.
Q4. What is delivered after the inspection?
Short time-stamped video clips for each area, photographs, written notes on condition and a summary page, usually within 24 hours.
