ULTRASONIC SPEED SENSOR
14
1.10 Maintenance
The retractable sensor units are supplied with a blanking plug, which must be
used when the Ultrasonic Speed transducer is removed for inspection,
maintenance, replacement or storage.
Removing the Ultrasonic Speed transducer from the ‘Flapper-Valve’
housing:
Inspect and lubricate the O-ring seals on the blanking plug using silicone
grease or petroleum jelly. Remove and discard the safety wire (Refer to Figure
1.6 on Page 1-9 of this manual). Remove the safety ring from one end of the
retaining pin. Using the remaining safety ring, withdraw the retaining pin from
the flapper-valve housing. Hold the blanking plug in one hand, with the other
hand pull the transducer out of the flapper-valve housing and replace it with the
blanking plug. Seat the blanking plug in place using a twisting motion until the
key fits into the notch in the housing. With practice, only a small amount of
water will enter the boat. Refit the retaining pin and safety ring.
Refitting the Ultrasonic Speed transducer is a reversal of the above procedure.
Note: ensure that the key on the transducer is correctly located in the notch on
the flapper-valve housing before fitting the retaining pin and pull ring. Secure
the assembly as previously described with new locking wire.
Cleaning the Ultrasonic Speed transducer
: Aquatic growth can accumulate
rapidly on the transducer surface reducing performance. Clean the surface with
a soft cloth and mild household detergent. If fouling is severe, use a stiff brush
or a putty knife. Take care not to cause scratches on the transducer face. Wet
sanding using fine grade wet/dry paper is permissible to remove stubborn
deposits.
Antifouling paint
: Surfaces exposed to salt water must be coated with
antifouling paint (refer to figure 4), Use only water-based antifouling paint.
Solvent-based paints must not be used. Solvent-based paints contain
‘keytones’ which may attack the plastic surfaces and damage the sensor. Re-
apply the antifouling paint every six months or at the start of each boating
season.
