Appendix 2 How To Install The Retraction Tank For Wooden Vessel - Furuno CH-250 Installation Manual

APPENDIX 2 HOW TO INSTALL THE
RETRACTION TANK FOR WOODEN VESSEL
Install the retraction tank for wooden vessel (prepared in Appendix1) as shown here.
Installation location considerations
Discussion and agreement are required with the dockyard and ship owner in deciding the location
for the retraction tank (hull unit). When selecting the installation location, consider the following
points:
• Select an area where the noise and interference are minimal.
The point at 1/3 to 1/2 of the ship's length from the bow or near the keel is the best. The center
of the retraction tank should be within 1 meter of the keel to prevent a rolling effect.
• Install the retraction tank off the keel.
Do NOT install the retraction tank on the keel and mounting hole for the retraction tank should
not be contact with the keel.
Mounting range
• Select a place where interference from the transducers of other equipment is minimal.
The hull unit should be at least 2.5 meters away from the transducers of other sounding equip-
ment.
• Select a place where no obstruction should be around the full-lowered transducer.
No obstruction should be in the fore direction since it causes a shadow zone and aerated
water, resulting in poor sonar performance.
• The distance between the bottom line of the keel and retraction tank should be 50 mm.
When the distance between the bottom line of the keel and retraction tank is more than 50 mm,
the echo beam may be interrupted with the keel or other ship's bottom structures.
Bottom line of the keel
• Install a flow rectification component to the hull where the transducer projects.
Install a fairing or stainless plate as the flow rectification component. See the next page to
select a faring or stainless plate.
1/3
1/2
Keel
≤ 1000
AP-7
Retraction tank
Keel
Within 1 m
Bottom line of the retraction tank
Echo beam area