User manual SIMRAD PI PURSE SEINE HYDROPHONE INSTALLATION REV D

[. . . ] Installation manual Simrad PI Catch monitoring system Purse seine hydrophone installation www. simrad. com MAXIMIZING YOUR PERFORMANCE AT SEA 851-164149 / Rev. D Simrad PI Catch monitoring system Purse seine hydrophone installation Document information Rev Rev. D Date 03. 06. 05 Information reorganized. Written by RBr Checked by KRa Approved by KRa © 2005 Simrad AS. ISBN 82-8066-054-2 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. [. . . ] When the seine is pursed in the sector from approximately 030_ to 150_relative to the bow, the hydrophone should be installed at an angle of 90_ to the vessel's centre line. 2 The most important elements with regard to the horizontal coverage area of the hydrophone are: 1 2 3 An unobstructed line-of-sight to the PI sensor(s) attached to the purse seine. The hydrophone is directed at the middle of the net when pursing. Two hydrophones may be used for applications requiring a large coverage area. 10 851-164149 / Rev. D Installation manual Figure 1 Horizontal coverage area The illustration shows a hydrophone installed at an angle of 70 degrees to the vessel's center line. (A) = The PI hydrophone (B) = The horizontal coverage area Vertical coverage area The hydrophone has a vertical beam width of -30_ and should be tilted so that the most important part of the seine is adequately covered. Tilt should be no less than -15_ in most instances with the optimal tilt angle depending on the size (length/depth) of the seine in use. Heeling of the vessel after the seine is set must also be taken into consideration. For a large purse seine (about 1000m or longer) the recommend a tilt angle is -15_ plus the estimated angle of heel when the net is set. For smaller and deeper seines it may be necessary to increase the tilt angle. 851-164149 / Rev. D 11 Simrad PI Catch monitoring system / Purse seine hydrophone Tilt angle The tilt angle is a function of net length and depth and may be estimated as follows: = - [arctan (depth/length * ) - 15_+ ] = tilt angle = angle of heel (to port) after deploying the purse seine to starboard The following table gives some examples of recommended tilt angles for common size pure seines: Recommended tilt angles Net length/depth in meters Recommended tilt angle * 250 / 50 --15_ 350 / 100 --25_ 650 / 150 --20_ 850 / 180 --20_ 1500 / 200 2000 / 200 --15_ --15_ *The tilt angle should be increased accordingly if the vessel heels after the seine is shot. Tilt angles of less than --15_ are not recommended. 12 851-164149 / Rev. D Installation manual Mounting arrangement The PI purse hydrophone 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. Information regarding through-hull penetration is also described to compliment the rules and regulations of the respective vessel's classification society. Referenced drawings PI Purse hydrophone, outline dimensions, page 27 PI Purse hydrophone, cutout, page 28 Purse hydrophone, keel mounted, steel or aluminum, page 29 Purse hydrophone, keel mounted, sandwich or wood, page 32 Purse hydrophone, blister installation, page 35 851-164149 / Rev. D 13 Simrad PI Catch monitoring system / Purse seine hydrophone 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 PI 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 PI 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. 14 851-164149 / Rev. D Installation manual Free standing hydrophone in blister If there is no risk that hull protrusions will be fouled by the purse wire, mounting the hydrophone in a freestanding blister is a viable option. Free standing hydrophone in blister: (A) = Tilt angel (B) = Vertical coverage area (C) = Free standing hydrophone in blister (pipe diameter 200 to 250 mm) (1) = Approximately 400 mm, minimum 250 mm is required (2) = Must exceed 700 mm. Should this solution be chosen, the following must be taken into consideration: · The centre of the hydrophone's beam must be directed as much as possible toward the bottom of the net where the PI sensor(s) are located. [. . . ] These activities are subject to individual approval by the respective classification society for the vessel in question. Order numbers Steel hull cable gland kit: 599-202216 Wood/GRP hull cable gland kit: 119-038200 Small vessel cable gland kit: 599-202182 851-164149 / Rev. D 21 Simrad PI Catch monitoring system / Purse seine 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. (A) = Steel conduit (B) = Stuffing tube, DNV approved carbon steel st52. 3 (C) = Washers, 24 x 8 x 2 mm (D) = Rubber gasket (E) = Packing nipple. Make sure that you do not damage the hydrophone cable by tightening the packing nipple too hard! [. . . ]