Simrad PI32 User manual

PI32 Bottom sensor attachment
Contact -
bottom sensors can detect bottom contact with a precision of just a few centimeters when
correct stay and detection chain lengths are used. Optimal sensor performance requires that these
lengths are configured with regard to both each other and the gear in use (the standard delivery
includes a 63 cm stay and 39 cm detection chain for use with 14 to 16 inch bobbins or rock hoppers).
Configuration -
the desired bottom detection distance is relative to the diameter of
the rock hoppers, bobbins or other gear in use. This relationship can be determined
and precise stay and detection chain length adjustments made as described below.
Setup
- lay the bottom sensor on an elevated surface and observe detection wire movement while
simulating bottom contact by raising the weight. Adjust the detection chain length as necessary. Tilt the
weight approximately 25°(
α
is due to drag through the water) opposite the towed direction and adjust
the stay length so that it begins to be taught. Avoid extra links at the weight ends when shorting chains.
IMPORTANT: Weights must be removed from a bottom sensors with a long stays and detection
chains before they transit the drum when hauling to prevent damage.
To attach a PI32 Bottom sensor:
1.) Locate the middle of the footrope and bend the attachment ring for the stay to the “bottom” and
two strops attached to karabiners on either side to its “top”. The strops should create a bridle about
15 to 20 cm in length that will securely hold the bottom sensor in a stable position.
2.) Bend the penetration ring for the detection wire about 30 cm below the footrope as illustrated.
Attach the bottom sensor and check that its feeler strap passes through the centre of the penetration
ring. Remove the netting on the inside of the penetration ring.
3.) Attach the rubber strops so that the bottom sensor is held horizontally when towed.
IMPORTANT: Carefully attach the sensor to the inside of the trawl so that it is not subject to
damage or torn off during fishing operations. The sensor’s feeler strap must always be allowed to
pass freely through the centre of the penetration ring when it is deployed.
Rock hopper,
bobbins, etc.
Attachment ring for the
stay bent securely to the
“bottom”of the footrope.
Karabiners are bent securely to the “top” of the footrope. If the bottom sensor is
attached to the wings, the length of the lashings must be adjusted so that the sensor
points toward the mother vessel when towed.
Penetration ring for
the feeler strap.
Weight and stay hang
freely under the trawl.
30 cm
Touch Down
Feeler strap
Detection
chain
Weight
Lift Off
Stay
Rock hopper
Bottom
End link
(851-164641B)
Note 1
Note 1
Note 1:
The stay can also be attached to the steel spacer between the bobbins/rock
hopper if the footrope is held fairly stable relative to the gear.