Installation manual

Purse seine hydrophone installation
55
851-165187 / Rev.A
Keel mounted shoes
The hydrophone shoe may be keel mounted to avoid creating an
appendage to the hull which may foul the purse wire.
Keel mounted hydrophone shoe:
(A) = Tilt angel
(B) = Vertical coverage area
(C) = Keel mounted hydrophone with
fairing
Should this solution be chosen, the
following must be taken into
consideration:
• The hydrophone must have an
unobstructed line-of -sight to the PI54
sensor(s) attached to the seine.
• The centre of the hydrophone’s beam
must be directed as much as possible
toward the bottom of the net where
the PI54 sensors are located. The tilt
angle must be increased with regard
to the expected heel of the vessel.
• For a short and deep seine a tilt angle (A) of 20_ to 25_ is
recommended. For a short and shallow or large seine a 15_
tilt angle may be best.
• If monitoring of the headline under pursing is desired the
hydrophone should not be tilted more than 15_.
• The hydrophone shoe must be mounted as deep as possible
on the keel, but not so deep that it may be damaged while
docking.
• The hydrophone shoe must be streamlined to avoid creating
turbulence and underwater noise.
• For applications that require extensive coverage, regardless
of net size, several hydrophones may be installed with
different tilt angles.