Raja Laut - Marine Services

1. Hull Cleaning (for yachts and commercial vessels of all sizes, including tankers and container ships)

Most of our work is carried out using the scraper system. This is more efficient and versatile than brushes. High percentages of hard and composite fouling of between FR90 and FR100 are typical of tropical waters and oysters, barnacles, corals and hydroids are removed without any damage to the underlying antifouling.

Underwater propeller polishing and maintenance of smooth propeller surfaces are vital to energy saving and optimising efficiency. Underwater pneumatic grinding and brushing tools are used to polish propellers.

2. Inspections / Surveys

Visually inspecting the hull and appendages, in accordance with NAVSHIPS Technical Manual and Waterborne Underwater Hull Cleaning of Surface Ships, for fouling according to the Fouling Rating (FR) and percentage cover of fouling, paint condition according to the Paint Deterioration Rating (PDR), corrosion, damages and overall condition.

We will normally use the ship's dry docking plan, accompanied with photos, to produce a Survey Plan. Documentation of fouling conditions and damage includes critical areas of the underwater body and in particular the Survey Plan pays attention to:

• All sonar and sonar domes or unpainted surfaces (particularly propellers and masker belts)

• All protruding appendages (that is, bilge keels)

• Cathodic protection systems; zincs, impressed current anodes, references cells, and dielectric shields

• Junctions of hull surface with struts, stern tubes, sonar dome, and other appendages

• Keel block and side block areas from last drydocking

• Sea chests, ballast tanks, and hull openings

• Previously identified damaged areas

3. NDT (None Destructive Testing)

• Thickness measurement of plates using an underwater ultrasonic thickness probe

• Determination of whether catodic protection system is effective through corrosion measurements using corrometer with silver/silver chloride half cell

4. Welding and Cutting

Welding sacrificial anodes, doubler plates, rope guards etc. Wet water welding, although far from being as strong as dry welding, is commonly used for quicker, cheaper or emergency repairs, allowing the vessel to complete its voyage after a mishap. Oxyarc cutting is used for cropping plates, bent bilge keels and even non ferrous metals such as propeller blades.

5. Sealing

From time to time, sea valves give trouble and when it does happen, it is not always convenient to wait until the next dry docking. It is therefore, essential that sea valves can be opened while the vessel remains afloat. Sea chests and overboards can be made watertight to allow for replacement or servicing of valves and sea cocks. Ropeguards are made watertight for removal of packing or lignum vitae.

6. Layup Services

Fabrication and positioning of blanks over sea chests if the vessel is to be laid up for some time. This method prevents the buildup of fouling within the sea chests and allows for faster subsequent reactivation . Similarly, round overboards are plugged with softwood plugs up to 12" - above this size plywood blanks with foam seals are inserted.