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.
Prerequisites
The vessel is in dry dock. The SY50 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
•  Ratchet (Socket: 13 mm)
•  Low‑strength threadlocker (Loctite 222 (or similar))
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.
Context
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 Lower the transducer to its bottom position.
How to manually lower and hoist the transducer depends on:
•  Hoisting motor without brake
•  Hoisting motor with brake
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 Hoist the transducer to its upper position.
Further requirements
The contractor or shipyard must keep a daily paint log recording all relevant information from the surface treatment.