Furuno GP-1670F Operator's Manual page 144

13. INSTALLATION
19°-22° transom angle (small aluminum and fiberglass boats): Position the
shim with the tapered end up.
transom
3. If the bracket has been temporarily fastened to the transom, remove it. Apply a
marine sealant to the threads of the three #10 x 1-1/4" self-tapping screws to pre-
vent water seeping into the transom. Screw the bracket to the hull. Do not tighten
the screws completely at this time.
4. Repeat step 1 to ensure that the angle of the sensor is correct.
Note: Do not position the sensor farther into the water than necessary to avoid
increasing drag, spray, and water noise and reducing boat speed.
5. Using the vertical adjustment space on the bracket slots, slide the sensor up or
down to provide a projection of 3 mm (1/8"). Tighten the screws.
13-10
11º transom angle
2º-10º
NO SHIM
angle
shim with
taper down
YES
YES
parallel parallel
12º-18º transom angle
NO SHIM
YES
NO
slight
angle
angle
reversed
Cable cover
Cable
clamp
Hull projection 3 mm (1/8")
19º-22º
transom
angle
shim with
taper up
YES
parallel
NO
angle too
steep
50 mm (2")