What are the Measures for Underwater Ship Inspection

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Ships require regular checks and inspections to maintain risks and repair damages. It is hard to check the submerged areas unless the ship is brought out to the dry dock. This is not practically possible, and therefore marine engineers have to resort to another technique to assess the ships – the underwater ship inspection. Qualified divers go below the waterline and inspect the submerged areas of the ship. In so doing, any problems can be detected, preventive measures, and remedial actions are taken quickly, ensuring prolonged and costly repairs are avoided at a later stage.

The underwater inspection of a ship must be carried out under the supervision of a classification society inspector. Ship hull surveys are a recognized diving company that inspects after they are tested and approved for competence. Its recognition at the hands for performing the works as to surveying the ships.

The situations under which an in-water survey is carried out include:

Before a scheduled repair.
During the assessment of the vessel’s condition upon its sale, purchase, or lease.
In case of an unplanned situation such as complicated weather conditions, landing on a sandbank, or damage after a collision with other transport objects.
Necessities for renewing/obtaining a license for the transportation of goods, passengers, or a permit of operation.

The divers should carry out the following arrangements and measures when inspecting ships underwater:

Master’s statement

Before partaking in the in-water survey, the Owner’s/Master’s representative must provide a declaration of the actual or suspected damage that has happened since the previous dry-docking was done.

Survey site

The survey site that has been proposed should be in an area that is protected with good underwater visibility or rather with calm, clear water. The visibility we’re talking about should be more than 2 meters high. Visibility is essential as it can easily ascertain whether the hull has undergone permanent set down or setup. The current effects should also be given special attention.

Hull condition

For the external survey, the hull should be clean. The Marine Surveyor should further ascertain that the quality and method of pictorial presentation are satisfactory and through the information presented. A reliable assessment can be made of the hull’s condition. If the equipment or conditions deteriorate, then the survey should be discontinued immediately, especially if the deterioration is to the extent that the communications or the transmitted pictures are no longer acceptable.

Underwater Areas

A competent diver should examine the entire vessel below the waterline using closed-circuit television. There should also be a two-way communication capable of being monitored by the Marine Surveyor as it is required. The in-water survey should also be carried out when the vessel is in a Light Operating Condition where practicable. This facilitates the survey.

Above Waterline Areas

The Marine Surveyor should further examine the exposed portions of the appendages and the outside of the shell plating above the waterline. All necessary means and requirements should be provided to enable the surveyor to accomplish this visual examination.

Internal Inspection

The internal structure should be examined as considered necessary to confirm or clarify the findings where a defect or damage is suspected or detected due to the Master’s statement or in-water survey. The vessels that operate in the ice should have their internal structures examined too so that the areas that are susceptible to ice damage are looked at keenly. And therefore, hazards associated with entering ship tanks should be given attention.

Report

Pertinent color photographs, copies of diver’s reports, and videotapes should be submitted to the Ship Safety Headquarters and Marine Surveyor for recording purposes.

In a nutshell, before carrying out the exercise, divers should also:

Be equipped with video-equipment and special instruments according to the approved survey program. They should dive into the required depth.
Examine propellers thoroughly, estimation of their state, corrosion on the surfaces defined, and cracks availability or unavailability.
In case of discussion of the disputable matters, repeated and more detailed examination and the defects should be captured by video record and photography.
Since some simultaneous repair works can accompany some underwater inspection, such urgent and partial repair helps to prolong the reliability of the ship’s operational characteristics and decreases the emerging risks to a considerable extent.
The inspector observes the inspection and constantly sees the image on his screen and can adjust the divers’ work and direct their actions. The underwater part of the hull, bottom and side openings, bilge keels, welded seams, riveted joints, and many others are examined, in a word, everything that requires checking and inspection.

Conclusion

Thanks to a scheduled inspection, any violations in the vessel’s structure can be detected promptly and eliminated. In case of an abnormal situation, an unscheduled inspection and elimination of defects can be made to prevent an accident.