Boxship bow thruster overhauled without drydocking

The task was performed in Rotterdam, using the Antwerp-based company’s own workboats. The Hydrex catamarans are equipped as dive support stations with hydraulic cranes, winches, nautical and communication equipment and a dive control room. The company says that they can be used for a variety of operations and deployed from Antwerp to other locations in Belgium, the Netherlands, the UK and France. This, claims Hydrex, increases flexibility of operations and helps to keep costs down for clients.

Having undertaken basic preparation and loaded the necessary equipment on board, the team arrived in Rotterdam, and divers installed flexible mobdocks on both sides of the thruster tunnel. Next they emptied all water from the tunnel. This created a dry working area around the bow thruster unit. The team could then detach the bow thruster blades one by one.

The blades were replaced by a blind flange to prevent oil leaking from the thruster and water from ingressing. Next the dive team removed the flexible mobdocks, concluding the first part of the operation.

The following step was to secure the gearbox with hoisting equipment. The team then disconnected the bow thruster unit from within the machinery room and lowered it onto a cradle. This cradle was designed especially for thruster operations. It can be adjusted to the size of the unit. The cradle is intended to prevent the thruster rom tipping over, allowing the divers and technicians to remove the unit in a single operation.

The next step was to load the bow thruster onboard the Hydrex workboat, ready to be overhauled. Next the team securely sealed off the ship’s machinery room by positioning a flange over the space connecting the thruster tunnel to the room. This allowed the vessel to sail until the overhauled unit is reinstalled.

The bow thruster unit was transported to the Hydrex headquarters on the deck of the workboat, for onward transportation to the manufacturer for overhaul.

According to the company, performing such tasks on a tight schedule requires considerable planning. The company claims that its staff are familiar with such operations, and have the relevant know-how and access to the right equipment. Hydrex says its technical department is capable of executing all the required planning, and its diver/technicians are trained and qualified to perform class-approved repair procedures in harsh conditions.