Painting the transducer face

Marine growth (biological fouling) on the transducer face reduces the performance. We suggest that you paint the transducer face immediately after installation, and then again as often as required to maintain the protection. It is particularly important to do this if you operate in waters with a lot of marine growth.

The vessel is in dry dock. The ST90 system is turned off. The following tools and consumables are required:

  • Personal protection
  • Fresh water
  • Plastic brush
  • Mild synthetic detergent
  • Fine‑grade sandpaper (240 inch grit size)
  • Primer
  • Anti‑fouling paint
  • Wet film gauge
  • Airless spray
Note:

Because some paint types may be aggressive to the polymer in the transducer, consult our list of approved anti-fouling paints.

Two persons are needed to do the task.

  • One person must stay in the sonar room to operate the hull unit.
  • One person must stay in the dry dock, under the hull, to make sure that the transducer is not lowered too far down.

Proper oral communication must exist between the sonar room and the dry dock personnel.

The transducer is not designed with any protection against biological fouling. Anti-fouling paint may therefore be applied to the transducer face. To minimize the negative acoustical effects the layer of anti-fouling paint must be as thin as possible.

Note:

The use of anti-fouling paint will reduce the acoustical performance of the transducer. The properties of the transducer face combined with the thickness of the anti-fouling paint can also affect the overall performance. Kongsberg Discovery cannot be held responsible for any negative consequences of the anti-fouling paint.

Observe the relevant instructions and safety information provided by the paint manufacturer.

Procedure

  1. Make sure that all power to the hull unit is disconnected.
  2. Make sure that you have sufficient height between the hull and the dry dock floor.
  3. Lowering the transducer:
    1. Use a spanner to open the door on the Motor Control Unit.
      Warning:

      High voltages are used. This equipment must be serviced only by qualified personnel familiar with high-voltage equipment and the potential hazards involved. Failure to observe this precaution could result in bodily injury. You may be exposed to electric shock. Read and understand the applicable first aid instructions related to electric shock.

    2. Locate the Motor Protecting Switch (S301).
    3. Deactivate the Motor Protecting Switch (S301) by pressing the operating handle to OFF.
    4. Locate the hand crank inside the Motor Control Unit.
    5. Remove the hand crank from its storage position.
    6. Remove the plastic plug on the top cover of the hull unit.
    7. Mount the hand crank onto the stub shaft through the hole in the top cover.
    8. Locate the brake release screw on the motor.
    9. Use an 4 mm Allen key to rotate the screw clockwise until the motor brake is released.
    10. Turn the crank until the transducer is fully lowered.
  4. Clean the transducer thoroughly.

    Make sure that you remove all oil grease residues, as well as salt and other contamination.

  5. Allow the transducer surface to dry.
  6. Abrade the transducer surface using a sanding paper with 240 inch grit size.

    Do not exceed a surface roughness (Rmax) of 35 microns as this can influence the transducer performance.

  7. Remove all dust.
  8. Apply the primer, and let it dry.
  9. Apply the paint.

    Observe the instructions provided by the paint manufacturer. Use airless spray. Apply the minimum specified film thickness per coat and for the complete layer. It is not possible to measure dry film thickness on transducer surface. You must therefore use a wet film gauge to frequently measure the paint thickness.

    Note:

    We strongly recommend that you do not use a paintbrush and/or a roller.

  10. Allow the paint to dry.
  11. Hoisting the transducer:
    1. Mount the hand crank onto the stub shaft through the hole in the top cover.
    2. Turn the crank until the transducer is fully retracted.
    3. Loosen the brake release screw to engage the motor brake.
    4. Check with the hand crank to ensure that the motor brake is engaged.
    5. Remove the hand crank from the stub shaft, and mount it in its storage position in the Motor Control Unit.
    6. Activate the Motor Protecting Switch (S301) by pressing the operating handle to ON.
    7. Make sure that the Hoist/Lower Switch is set to REMOTE.
      Note:

      For normal operation from the Operating Panel, the switch must be set to REMOTE.

    8. Close the door on the Motor Control Unit.

The contractor or shipyard must keep a daily paint log recording all relevant information from the surface treatment.