The role of cofferdams in ship repair operations
When a structure has to be built beneath the water surface, a cofferdam is created. A cofferdam is a temporary watertight structure designed to keep water and/or soil out of the excavation in which a structure is built. The word "cofferdam" comes from "coffer" meaning box, so a cofferdam resembles the shape of a box. There are mainly two different types of cofferdams used in the marine industry:
1. Fully Enclosed
These type of cofferdams are fully sealed off from the water on all sides. They are created mainly to intervene the water flow into the hull or equipment. They are widely used in repairing ship hulls. A tank-like structure with an open top is attached to the ship while the vessel is still in water. The water is pumped out of the structure allowing work to be carried out on the ship’s hull from inside the ship’s tank.
2. Open Cofferdam
These type of cofferdams are needed to have dry access to the equipment on the surface of the water. They are widely used in shallow waters (30-35 ft. depth).
Working underwater is certainly more difficult and costly than working over land and it is very important to minimise work underwater in ship repair activity. A cofferdam provides safe enclosure from the water to assist in performing:
- - Hull repairs
- - Replacement of hull mounted fittings i.e. logs, sounders, anodes etc
- - Replacement of stern seals, rudders and stabilisers
- - Repair and replacement of tunnel thrusters and concrete structures i.e. docks, jetties etc
The main advantage of cofferdams is that it avoids the need for emergency dry docking to perform repair and replacement. This results in huge savings in time and cost. Materials used in cofferdams are reusable and easy to place and remove.
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KBA Marine is fully compliant to local and international safety and health standards, and our team of professional tenders, divers, dive supervisors, diver medical technicians and other support personnel are dedicated to safety and getting the job done right. We invest in the right equipment and training that is fully compliant to ensure safety in all diving operations.
All our divers are certified in accordance with the Singapore SS511 Commercial Diving Code of Practice, such as LSP ISO 29990 Commercial Diver training and certification or equivalent (HSE UK, ADAS) and they also undergo our in-house safety and task training programs to enhance their skills.
KBA Marine can provide cofferdams of any size required by our clients. To know more, please contact us.