- info@nagoyaunderwater.com
Get In Touch
Get In Touch
Owners often ask a simple question: what can actually be repaired while the ship is in the water? The list is longer than many expect. This page sets out the main types of underwater ship repair in Nagoya Port, and where the limits are.
Dents, small cracks and holes in the shell plating can often be repaired with welded patches, doubler plates or, for temporary leak control, a bolted patch. The Diver inspects the damage, measures it and agrees a plan with the surveyor. Where the plate is badly wasted, the repair may need a larger doubler or a dry dock for a proper steel renewal.
Minor propeller damage, such as nicks and burrs, can be dressed and polished in the water. Rudder fittings, pintle caps, drain plugs and anodes can be repaired or replaced. Some rudder work is limited by the design and may need a dock. The Diver checks the condition first and tells the owner honestly what is possible.
Overboard discharge valves, sea chest valves, strainers, gratings and pipe flanges can be repaired or replaced with a temporary blanking of the opening. This usually requires cooperation with the engine room to isolate systems. A well planned job can swap a valve in a few hours without leaving the berth.
Replacing worn sacrificial anodes is one of the most common underwater jobs. We can weld or bolt new anodes in place and check the impressed current system where fitted. Keeping the anodes in good order protects the Hull and the propeller from corrosion between dockings.
Bow and stern thruster gratings, tunnel inserts and some blades can be inspected and repaired. A damaged grating can often be replaced by the Diver. Blade replacement is more demanding and depends on the thruster type.
Repairs that involve major structure, tank boundaries or large amounts of steel renewal usually need a dry dock. Heavy corrosion that has weakened the plate over a large area is also a dock job. Our approach is to inspect first, give the owner a clear picture and recommend afloat repair only when it is safe and acceptable to class.
Send us the ship's details, a description of the problem, and any photographs the crew have. We plan an inspection dive and a repair proposal, and we discuss the option with the surveyor so there are no surprises.
Repairs afloat use marine-grade steel plate, special waterproofed electrodes, bolts, gaskets, epoxy and sealing compounds. We carry the common items and order special ones when the plan calls for them. The Diver team brings cutting and welding equipment, power supplies, and lifting gear. For a larger repair, a crane or a workboat may be added, and the plan names each item.
For a typical case, the inspection is on day one, the plan and approval on day two, the repair on day three, and the report and handover on day four. Faster schedules are possible if the class surveyor is available and the weather is good.
Q1. What can be repaired underwater?
Shell plating patches and doublers, minor propeller damage, rudder fittings, valves, pipes, gratings and anodes. Major structural repairs usually need a dry dock.
Q2. How long does a valve replacement take?
A well planned replacement of an overboard valve, with the opening temporarily blanked, can be done in a few hours.
Q3. What is the first step for any repair?
An inspection dive that films and measures the damage, so the owner and the surveyor can agree on an approach.
Q4. When is dry-docking the better choice?
When the repair affects major structure or tank boundaries, or where heavy corrosion has weakened the plate over a large area.
