Installation manual Simrad PI Catch monitoring system Trawl hydrophone installation www.simrad.
851-164472 / Rev.
About this document Rev Date Written by Checked by Approved by Rev.B 03.06.05 RBr KRa KRa Information reorganized © 2005 Simrad AS. All rights reserved. ISBN 82-8066-055-0 No part of this work covered by the copyright hereon may be reproduced or otherwise copied without prior permission from Simrad AS. The information contained in this document is subject to change without prior notice.
Installation manual Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Installation precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Pre-installation check-list . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Simrad PI Catch monitoring system / Trawl hydrophone IV 851-164472 / Rev.
Installation manual Introduction The purpose of this document is to provide general guidelines for the installation of the PI hydrophone for trawling. Note: If your vessel shall be fitted for purse seine operations, DO NOT install the hydrophone(s) as explained in this document! Order numbers Trawl hydrophone, complete: HYD-205254 Trawl hydrophone, without cable gland: HYD-205826 Topics 851--164472 / Rev.
Simrad PI Catch monitoring system / Trawl hydrophone Installation precautions Caution: 2 The following precautions must be observed. Failure to do so can result in damage to the hydrophone which may render the PI Trawl hydrophone system inoperative. 1 Observe the maximum allowable torque warning of 5 Nm when tightening the hydrophone studs. 2 Use only M8x35 socket countersunk head screws for mounting the hydrophone. 3 Secure threaded hydrophone hardware with Loctitet 270 or the equivalent.
Installation manual Considerations Correct installation of PI hydrophone(s) is vital to system performance. Several variables must be taken into consideration, the most important of which is the vessel’s construction. This guide is for use in selecting the best location for the hydrophone and includes a brief description of areas to be avoided. Note: Simrad strongly suggests that this information is read thoroughly, and that the instructions are understood and followed.
Simrad PI Catch monitoring system / Trawl hydrophone Boundary water layers: (A) = Turbulent flow (B) = Laminar flow (C) = Air bubbles in the water Air bubbles may also be introduced into the boundary layer. If the vessel’s hull has little flare and is relatively narrow, bubbles may escape to the sea surface without incident. On the other hand a wide, flat hull with minimal deadrise is prone to trapping air bubbles no matter how little flare it has.
Installation manual Propeller noise A vessel’s main propeller is the dominant source of underwater acoustic noise. When ever possible, hydrophone(s) should be located as far a way as possible from the main propeller and never closer than ten meters. Hydrophone(s) should not be mounted in the direct acoustic path (line-of-sight) of the main propeller unless absolutely necessary.
Simrad PI Catch monitoring system / Trawl hydrophone When not in operation, bow/sternthruster tunnels create turbulence and hence underwater noise when a vessel is under way. Also, as a vessel pitches in heavy weather, thruster tunnels may fill with air or aerated water which can disturb hydrophone reception when released. Hydrophone installation should take into regard the noise and down stream disturbances found around and aft of thrusters.
Installation manual Drop keel In the event the vessel is equipped with a drop keel, the hydrophones should be mounted aft of it. The choice between installing a one, or two hydrophone system should be based on the same horizontal and vertical coverage requirements for vessels operating under similar conditions with fixed keels. 851--164472 / Rev.
Simrad PI Catch monitoring system / Trawl hydrophone Pre-installation check-list Choosing the optimal locations for hydrophones is not always easy, but decisions made at this phase of the installation process are critical to future system performance. Determining the best configuration for a given vessel often involves a compromise between contradicting requirements.
Installation manual 851--164472 / Rev.B 10 The hydrophone that is closest to the main propeller should be located on the port side of the vessel and have the greatest tilt. 11 If both hydrophone are located equally distant from the main propeller, but are tilted differently, the starboard hydrophone should be tilted the most because underwater acoustic noise is more prevalent on that side of the vessel. 12 Locating hydrophones at the after end of a bulbous bow can produce good results.
Simrad PI Catch monitoring system / Trawl hydrophone Optimal location of trawl hydrophones The most influential factors effecting hydrophone reception common to most vessels are: • Noise from cavitation generated by the main propeller. • Air bubbles in the water around the hydrophone which impede acoustic signals. • Noise from other acoustic equipment mounted in close proximity.
Installation manual 1200 mm, but no less than 700 mm) to avoid turbulence. To also aid in reducing the effects of turbulence, hydrophones should be installed as deeply as possible (preferably 600 mm, but not less than 400 mm) from the vessel’s outer hull. When ever possible, the distance from the keel to the bottom of the hydrophone blister should not exceed 50 mm which can be adjusted by countersinking the installation.
Simrad PI Catch monitoring system / Trawl hydrophone degrees. To maximise coverage using two hydrophones when trawling in both deep and shallow water tilt one preferably 15 degrees and the other preferably 30 degrees. The hydrophone closes to the propeller should be tilted the most and care should be taken with regard to underwater acoustical noise. • Hydrophone cables pass through a vessel’s hull below its water-line.
Installation manual Coverage area, orientation and tilt Once the fore-and-aft placement of the hydrophone is decided, it is equally important to carefully consider its horizontal and vertical orientation. Hydrophone orientation can have a large influence on system performance. Hydrophones must be configured so that they overlap one an other in the horizontal plane. Tilt is decided by the actual depth of the gear.
Simrad PI Catch monitoring system / Trawl hydrophone Vertical coverage area I Dual hydrophone installation with hydrophones equally distant from the bow, but tilted differently. Typical tilt configuration for operation in both deep and shallow water when the hydrophones have the same distance from bow. The hydrophones may be installed in shoes or blisters.
Installation manual Vertical coverage area II Dual hydrophone installation with hydrophones different distances from the bow, and tilted differently. Typical tilt configuration for operation in both deep and shallow water when hydrophones have different distances from bow.
Simrad PI Catch monitoring system / Trawl hydrophone Simrad recommends that hydrophone tilt be preferably 20 degrees for normal trawling. If the vessel plans to operate in deep water the tilt can be increased to approximately 30 to 35 degrees or reduced to 10 degrees if trawling will be performed at or near the surface. Should a vessel need to operate in both deep and shallow waters two hydrophones be employed, each tilted preferably 15 and 30 degrees respectively.
Installation manual Mounting arrangement The PI trawl hydrophones are delivered ready for installation in either freestanding or keel mounted shoes (which are to be built by the shipyard responsible for the installation). Several alternatives with corresponding detailed drawings have been included in this manual to cover the majority of installation options available.
Simrad PI Catch monitoring system / Trawl hydrophone Freestanding hydrophones in blisters For trawlers that do not have to take a pursing wire into consideration, hydrophones can be mounted in specially constructed blisters offset from the vessel’s keel (preferably 1200 mm, but no less than 700 mm) to avoid turbulence. The picture shows an example of a freestanding hydrophone offset from the keel on a wooden vessel. Approximate blister location, view from stern.
Installation manual The farther away from the hull a hydrophone is mounted the more the effects of turbulence are reduced. Simrad recommends that hydrophones be installed as deeply as possible (preferably 600 mm, but not less than 400 mm) from the vessel’s outer hull. When ever possible, the distance from the keel to the bottom of the hydrophone blister should not exceed 50 mm.
Simrad PI Catch monitoring system / Trawl hydrophone Keel mounted shoes Hydrophones can be keel mounted to avoid creating appendages to the hull that could foul the purse wire. Keel mounted hydrophone shoes, top view. (A) = Keel (B) = Towards the bow (S) = Starboard shoe with hydrophone (P) = Port show with hydrophone Should this solution be chosen, the following must be taken into consideration: • Hydrophones must have an unobstructed line-of-sight to the sensors attached to the trawl.
Installation manual Mounting at the aft end of a shoe Hydrophones can be mounted at the after end of a transducer shoe for an echo sounder or other underwater acoustic equipment. The distance between the hydrophone and such equipment must not be less than one meter and the greater the separation, the better. Installing a hydrophone in close proximity to underwater acoustic equipment can reduce system performance due to interference. Hydrophone mounted at the aft end of a echo sounder transducer shoe.
Simrad PI Catch monitoring system / Trawl hydrophone Mounting at the after end of a bulbous bow Trawling hydrophones have been successfully installed at the after end of bulbous bows (for vessels trawling in deep water and require tilt angles from 25 to 35 degrees). Vessels equipped in this manner may experience signal loss in heavy weather due to bubbles or when pounding lifts the hydrophone out of the water.
Installation manual Dual hydrophone installation The PI system trawl hydrophones receive horizontally and vertically within 50 and 30 degree sectors respectively. Signals transmitted from sensors attached to towed gear must be able to be received on both sides of a vessel’s keel under normal operating conditions. When a single hydrophone is installed, it must therefore be mounted no more than five centimetres higher than the lowest point on the keel to ensure proper coverage on both sides of the vessel.
Simrad PI Catch monitoring system / Trawl hydrophone Hydrophone protection Warning: Do not perform hot work near, paint, scrape, hit, pry, force, sandblast, high-pressure wash or otherwise subject hydrophones to excessive force. Installation precautions The following precautions must be observed. Failure to do so can result in damage to the trawl hydrophone which may render the PI system inoperative.
Installation manual Vessels operation in colder climates should weld steel fins and protection plates installed around hydrophones to protect them from being damaged by ice. Detailed drawing must be made specifically to suite each individual vessel in question and the installation performed by an authority with the expertise to do so. Surface protection Maintenance and replacement costs can be reduced if those parts of the hydrophone installation that are open to the sea are protected correctly.
Simrad PI Catch monitoring system / Trawl hydrophone Location and marking After installation, the location of hydrophones should be clearly marked on the vessel’s hull (above the water-line) directly over them. This information will help prevent hydrophone damage when dry-docking the vessel.
Installation manual Hydrophone cable The trawl hydrophone is delivered with a 22 m cable. The cable is fitted with plug that fits the ANT socket on the rear side of the PI Operator Unit. The standard hydrophone delivery includes cable gland kit 599-202216 for steel hulls, and the hydrophone cable has been cut to allow this cable gland to be installed. General cable gland guidelines Hydrophone cables are passed through the hull using approved cable glands for the type of vessel in question.
Simrad PI Catch monitoring system / Trawl hydrophone Cable gland installation for steel hulls The cable gland kit for steel vessels is included with standard deliveries. The drawing shows a single hydrophone, but normally a typical installation includes two hydrophones with respective cables spliced in a junction box and run to the wheelhouse in a conduit. Cable gland for steel hull vessels. (A) = Steel conduit (B) = Stuffing tube, DNV approved carbon steel st52.
Installation manual Gland installation for wood or GRP hulled vessels A bronze cable gland kit is available for wood and GRP vessels. This kit is not included in the standard delivery, and must be ordered separately. The drawing shows a single hydrophone, but normally a typical installation includes two hydrophones with respective cables spliced in a junction box and run to the wheelhouse in a conduit. Cable gland for wood and GRP hulls. (A) = Packing nipple.
Simrad PI Catch monitoring system / Trawl hydrophone Cable gland installation for smaller vessels Cable glands made of plastic for those smaller vessels that do njot need to be classified are optional equipment for standard deliveries. This cable gland kit is not included in the standard delivery, and must be ordered separately.
Installation manual Splicing If you need to cut the cable, you must splice it correctly. Note: DO NOT solder the wires together with only electrical tape for insulation, as this will result in electrical noise and reduced operational performance. To splice the cable, use a metal junction box. The chassis of the junction box must be grounded, but the cable shielding must NOT be connected to the junction box ground.
Simrad PI Catch monitoring system / Trawl hydrophone Installation drawings Observe the following drawings. The drawings are also available on electronic format (DWG or PDF), consult your local dealer. 32 → PI Trawl hydrophone, outline dimensions, page 33 → PI Trawl hydrophone, cut-out, page 34 → PI Trawl hydrophone, mounting flange, page 36 → Free standing hydrophone in blister, page 38 → Hydrophone in keel mounted shoes, page 40 851--164472 / Rev.
Installation manual PI Trawl hydrophone - Outline dimensions 851--164472 / Rev.
Simrad PI Catch monitoring system / Trawl hydrophone PI Trawl hydrophone - Cut-out - Page 1 34 851--164472 / Rev.
Installation manual PI Trawl hydrophone - Cut-out - Page 2 851--164472 / Rev.
Simrad PI Catch monitoring system / Trawl hydrophone PI Trawl hydrophone - Mounting flange - Page 1 36 851--164472 / Rev.
Installation manual PI Trawl hydrophone - Mounting flange - Page 2 851--164472 / Rev.
Simrad PI Catch monitoring system / Trawl hydrophone PI Trawl hydrophone in blister - Arrangement drawing - Page 1 38 851--164472 / Rev.
Installation manual PI Trawl hydrophone in blister - Arrangement drawing - Page 2 851--164472 / Rev.
Simrad PI Catch monitoring system / Trawl hydrophone PI Trawl hydrophone in keel mounted shoes - Arrangement drawing - Page 1 40 851--164472 / Rev.
Installation manual PI Trawl hydrophone in keel mounted shoes - Arrangement drawing - Page 2 851--164472 / Rev.
E 2005 Simrad AS ISBN 82-8066-055-0
