Polemount Bracket - C-Max CM2 User Manual

CM2 Sidescan Sonar User Manual

20. POLEMOUNT BRACKET

Introduction
Some users prefer to use a rigid overside mount for the towfish in certain circumstances, instead of towing it.
The advantage is that the towfish is not endangered when manoeuvring in restricted depths or near
obstructions.
Note that the disadvantages of rigid mounting are
a) The towfish motion is not isolated from roll, pitch and yaw of the boat
b) The towfish altitude cannot be adjusted to give the optimum image; rigid mounting generally means
the towfish is too high off the bottom for best central coverage and for best shadow angles
c) The image from the beam passing under the hull can be affected by reflection from the hull resulting
in multipart distortion
An alternative to rigid mounting is towing from the bow or from the beam.
Fitting the Polemount Bracket
The positioning of the overside pole and its mounting to the hull is outside the scope of this manual.
Fit the CM2 polemount bracket to the lower end of the pole as shown in the illustration, tightening the U-bolts
and ensuring that shakeproof washers are fitted under the M8 nuts.
Tape the terminator in position using duct tape or similar.
Use cable ties to secure the tow cable extension, to prevent it oscillating and chafing in the flow.
Use another cable tie to secure the two halves of the yoke assembly together, located in the slot in the
bracket.
Version 3.6 (2008)
Fitting the Polemount Bracket
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20. Polemount Bracket