Furuno Ls4100 manual Adjusting, Sensor position and transom angle

Warning: Always wear safety goggles and a dust mask.

3.Using a 4 mm, #23, or 9/64” bit, drill three holes 22 mm (7/8”) deep

at the locations indicated. To prevent drilling too deeply, wrap masking tape around the bit 22 mm (7/8”) from the point.

Fiberglass hull: Minimize surface cracking by chamfering the gelcoat. If a chamfer bit or countersink bit is not available, start drilling with a 6mm or 1/4” bit to a depth of 1 mm (1/16”).

4.If you know your transom angle, the bracket is designed for a standard 13° transom angle.

11°-18° angle: No shim is required. Skip to step 3 in “Adjusting”.

Other angles: The shim is required. Skip to step 2 of “Adjusting”.

If you do not know the transom angle, temporarily attach the bracket and sensor to the transom to determine if the plastic shim is needed.

5.Using the two #10 x 1-1/4” self-tapping screws, temporarily screw the bracket to the hull. DO NOT tighten the screws completely at this time. Follow the step 1-4 in “Attaching the Sensor to the Bracket”, before proceeding with “Adjusting”.

Adjusting

1.Using a straight edge, sight the underside of the sensor relative to the underside of the hull. The stern of the sensor should be 1-3 mm (1/16-1/8”) below the bow of the sensor or parallel to the bottom of the hull.

2° -10°11° transom angle		19° -22°
transom	NO SHIM	transom
angle		angle
shim with		shim with
taper down		taper up
YES	YES	YES
parallel	parallel	parallel
12-18°transom angle
	NO SHIM
NO	YES	NO
angle	slight	angle
reversed	angle	too steep

Sensor position and transom angle

Note: Do not position the bow of the sensor lower than the stern because aeration will occur.

2.To adjust the sensor’s angle relative to the hull, use the tapered plastic shim provided. If the bracket has been temporarily fastened to the transom, remove it, Key the shim in place on the back of the bracket.

2°-10° transom angle (stepped transom and jet boats): Position the shim with the tapered end down.

19°-22° transom angle (small aluminum and fiberglass boats): Position the shim with the tapered end up.

3.If the bracket has been temporarily fastened to the transom, remove it. Apply a marine sealant to the threads of the two #10 x 1-1/4” self tapping screws to prevent water seeping into the transom. Screw the bracket to the hull. Do not tighten the screws completely at this time.

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