Operation Manual

ULTRASONIC SPEED SENSOR

1.9.1 Single Skin Hull

Drill a 3mm (1/8 inch) pilot hole from inside the hull. Using a 51mm (2

inch) hole saw cut a hole from the outside of the hull. Clean and sand the

area around the hole to ensure that the sealant will adhere properly to the

hull.

Figure 1.6 - Ultrasonic Speed Sensor Assembly

1.9.2 Cored Fibreglass Hull

Note: To install a thru-hull housing in a cored fibreglass hull, the core (wood or

foam) must be sealed carefully, the core must be protected from water

seepage, and the hull must be reinforced to prevent it crushing under the hull

nut and allowing the housing to become loose.

Drill a 3mm (1/8 inch) pilot hole from inside the hull. Using a 51mm (2 inch)

hole saw cut a hole from the outside of the hull through the outer skin only,

(refer to figure 3). Using a 60mm (2 3/8 inch) hole saw from inside the hull, cut

through the inner skin and most of the core. Apply only light pressure to the

hole saw after the inner skin has been cut through as the core material can be

very soft and too much force could result in damage to the outer skin.

Remove the plug of core material so that the inside of the outer skin and

the inner core are fully exposed. Clean and sand the inner skin, core, and

the outer skin around the hole.