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Without CCTV, an underwater survey depends on what the Diver says he sees. With CCTV, the surveyor and the superintendent see the same picture at the same time. That is why every inspection we run in Nagoya uses it.
The Diver wears a full-face mask with a camera and lights mounted on the helmet or held by hand. The signal travels up the umbilical to a control unit on deck, where it appears on a monitor and is recorded. A voice link lets the surveyor talk to the Diver directly, so he can say "go back" or "move closer to that weld" without waiting for the dive to end.
Port water is rarely clear. Silt, plankton and runoff reduce visibility, sometimes to less than one metre. LED lights help, but too much light in murky water can cause glare. Our technician adjusts the lighting for each section, and the Diver keeps the camera close to the plating. In poor conditions we trade wide views for clean close-ups, and we say so in the report.
Every dive is recorded in full, with a time stamp and the name of the ship on screen. The footage is saved on two devices on deck. After the dive, selected clips and photographs are exported into the report. The full video is delivered on request, usually as a download link, so the technical department can review it later.
If the superintendent or the class office cannot attend, we can send the live feed or a short summary clip by link when the internet connection on the quay allows. This does not replace the surveyor's attendance where class requires it, but it keeps the office informed.
The footage is evidence. It supports class discussions, claims against third parties, and repair planning. A clear video of a damaged plate is more useful than a page of description, and a good CCTV record helps the shipyard or our own team estimate the repair before a Diver goes down again.
CCTV is a tool, not a magic eye. In very poor visibility the camera sees little beyond the length of an arm. Glare from the lights can wash out detail. A camera cannot feel a weld that has a slight crack, and it cannot always tell the difference between a shadow and a dent. That is why the Diver stays close to the plating, wipes the area, and uses touch and measurement when the picture is not clear enough.
The ship's role is small but important. Please provide a safe place on deck for the control unit, power for the monitor if needed and a named contact for the surveyor. If the surveyor wants to watch from the bridge or the office, tell us in advance so we can arrange the feed. Clear communication before the dive saves time during it.
Q1. What is the typical visibility in Nagoya port water?
Port water often has visibility of 1 to 3 m, and it can be below 1 m after rain or heavy traffic. CCTV lighting and close-range work make up for this.
Q2. Is the whole dive recorded?
Yes. Each dive is recorded with a time stamp on two separate storage devices, so there is a backup if one device fails.
Q3. Can the surveyor speak to the Diver during the dive?
Yes. A voice link runs through the umbilical, allowing the surveyor and supervisor to give instructions in real time.
Q4. How soon do we receive the video?
Selected clips and photographs are in the report within 24 hours. Full video can be sent as a download link on request.
