Furuno FSV-75 Installation Manual page 12

1. MOUNTING
1.2.2 Guideline for how to shorten the retraction tank
The recommended tank length for 800 mm and 1100 mm travel hull units is as follows:
• 800 mm travel: 900 mm retraction tank is recommended.
• 1100 mm travel: 1200 mm retraction tank is recommended.
Shorten the tank as necessary so that the transducer positions well below the keel
when it is fully lowered. The following table provides guidelines for shortening the tank.
Refer also to the retraction tank installation drawing at the back of this manual.
Installation
Method
Travel
800 mm
travel
1100 mm
travel
Note 1: Adjust the position for the TX limit switch, according the retraction tank length.
For how to adjust the position for the TX limit switch, see section 1.2.8.
Note 2: When maximum length is removed and "D" is at minimum, the effect of aera-
tion is minimized because the transducer fully protrudes in water.
Guideline for the installation of the retraction tank
• If the keel plate on the inside of the hull is not adequate for installing the retraction
tank, install a secondary keel plate.
• Install the retraction tank where the keel plate and hull frame intersect.
• If there is no suitable location where the hull frame and keel intersect, install suitable
"T" shaped reinforcement ribs, then weld the base of the frame to the reinforcement
ribs and the sides of the reinforcement ribs to the hull walls or other nearby
reinforcement ribs. The reinforcement ribs should be secured in the fore, aft, port
and starboard directions.
• Install the reinforcement ribs as near as possible to the top of the retraction tank,
allowing 150 to 200 mm space for tightening of nuts and bolts.
• Fit a doubling plate (a plate added to another to give extra strength or stiffness) to
the location where the retraction tank is welded to the hull bottom. While it is
recommended that both sides attach to the hull, consult with the installer
regarding length and diameter.
• The thickness for doubling plates and reinforcement ribs is 12 mm minimum.
1-4
Cut 0-100 mm from the
end.
Cut 0-100 mm from the
end.
D
Cut 0-100 mm from the end.
Note that the length "D" must be less
than 200 mm.
Cut 0-100 mm from the end.
Note that the length "D" must be less
than 500 mm.
D