Nexus 21 CS4500-610 Antifouling Paint, Mounting Location, Installation, Hole Drilling, Bedding

Antifouling Paint

Marine growth can accumulate rapidly on the ultrasonic sensor’s surface reducing performance within weeks. Surfaces exposed to salt water must be coated with antifouling paint. Use water-basedantifouling paint only. Never use ketone-based paint, since ketones can attack many plastics possibly damaging the sensor.

ultrasonic insert

It is easiest to apply antifouling paint before installing the sensor, but allow drying time. Reapply paint every 6 months or at the beginning of each boating season. Paint the following surfaces

housing

outside wall below lowest O-ring

active face

(see Figure 2):

•Outside wall of the ultrasonic insert below lowest O-ring

•Active face of the ultrasonic insert

•Exterior lip of housing

•Bore of housing up 30mm (1-1/4")

•Blanking plug below lowest O-ring including exposed end

&valve

assembly

inside bore of housing

up 30mm (1-1/4")

exterior lip

Figure 2. Antifouling paint

Mounting Location

Turbulence-free water must flow under the ultrasonic sensor at all speeds. Choose an accessible spot with a minimum of 200mm (8") of headroom inside the vessel to allow for the height of the housing, tightening the nuts, and removing the insert.

•Fin keel sailboats—Mount the sensor on or close to the centerline and forward of the fin keel 150–300mm (1/2–1').

•Full keel sailboats—Locate the sensor amidships and away from the keel at the point of minimum deadrise.

•Displacement hull powerboats—Locate the sensor amidships near the centerline.

•Planing hull powerboat—Mount the sensor well aft to ensure it will be in contact with the water at high speeds.

Caution: Do not mount the sensor in an area of turbulence or

bubbles: near water intake or discharge openings; behind strakes, fittings, or hull irregularities; or behind eroding paint (an indication of turbulence).

Caution: Never mount the sensor directly ahead of a depth transducer, since turbulence generated by the housing will adversely affect the depth transducer’s performance, especially at high speeds.

Installation

Cored fiberglass hull—Follow separate instructions on page 3.

Hole Drilling

Warning: Always wear safety goggles and a dust mask.

1.Drill a 3mm 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 51mm or 2" hole saw, cut the hole from outside 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.

Bedding

Apply a 2mm (1/16") thick layer of sealant around the lip of the housing that contacts the hull and up the sidewalls 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 3). This will ensure there is sealant in the threads to seal the hull and to hold the hull nut securely in place.

P120 plastic housing		B120 metal housing
	ultrasonic insert
	cap nut
	safety wire
	hull nut
	washer
marine	hull	marine
sealant		sealant
	Figure 3. Bedding and installing
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