English Sea Data Set TH52
12
2.3.2 Installing the through hull fittings
3 Installation
Cored fiberglass hull—Follow separate instructions on page 3.
Hole Drilling
Warning: Always wear safety goggles and a dust mask.
1. Drill a 3 mm or 1/8" pilot hole from inside the hull. If there is a rib, strut or other hull
irregularity near the selected mounting location, drill from the outside.
2. Using the appropriate size hole saw, cut the hole from outside the hull. Flush
housing—Use a countersink tool to create a “seat” in the hull.
3. Sand and clean the area around the hole, inside and outside, to ensure that the
sealant will adhere properly to the hull. If there is any petroleum residue inside the
hull, remove it with either mild household detergent or a weak solvent (alcohol)
before sanding.
Metal hull—Remove all burrs with a file and sandpaper.
3.1 Bedding
Apply a 2mm (1/16") thick layer of marine sealant around the lip of the housing that
contacts the hull and up the sidewall of the housing. The sealant must extend 6mm
(1/4") higher than the combined thickness of the hull, washer(s), and hull nut (see
Figure 2). This will ensure there is sealant in the threads to seal the hull and to hold the
hull nut securely in place.
3.2 Installing
Caution: Never pull, carry, or hold the sensor by the cable as this may sever internal
connections.
1. From outside the hull, push the housing into the mounting hole using a twisting
motion to squeeze out excess sealant (see Figure 2). Align the arrow on the lip of
the housing to point forward toward the bow. If the sensor is not installed on the
centerline, angle the housing slightly toward the centerline to align it with the water
flow.
2. From inside the hull, slide the washer onto the housing. Aluminum hull less than
6mm (1/4") thick—Use an additional rubber, fiberglass, or plastic washer. Never
use bronze since electrolytic corrosion will occur. Never use wood since it will
swell, possibly fracturing the plastic housing.
3. Screw the hull nut in place being sure the notch on the upper rim of the housing
and the corresponding arrow on the lip are still positioned forward toward the bow.
(If your plastic housing has wrenching flats, do not clamp tightly, possibly causing
the housing to fracture.) Hand-tighten only. Do not over tighten. Wood hull—
Allow for the wood to swell.