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Chain & Wire Steering Systems Planning, Installation & Maintenance Guide EB-381

Chain & Wire Steering Systems Planning, Installation & Maintenance Guide EB-381 Planning & Sizing Pedestal Steering Systems Edson International 146 Duchaine Blvd., New Bedford, MA 02745-1292 • tel (508) 995-9711 • fax (508) 995-5021 The typical installation may vary in wheel size, sheave size, chain length, and quadrant size depending on the length and displacement of the boat and the type of sailing being done. For cruising and offshore work, a larger quadrant with more power output and more turns of the wheel hard over to hard over is preferred. For racing, a smaller quadrant with fewer number of turns and a larger wheel will provide faster action especially useful for downwind sailing. For recommended sizes, see the table below. Edson will also supply, upon request, Data Sheets and recommendations covering the best system for your boat. For boats being able to use more than one system, recommendations will be given in order of preference. For specific information for converting or planning your boat, send us your construction drawings and/or sales literature along with the type of steering system you wish to install. The chart below is composed of information gathered from our many years of leadership in marine steering. Due to the many variations of yacht design in areas of hull shape, engine horsepower and sail configuration, final recommendations must be approved by your naval architect. STEERER OUTPUT CHART The value of this chart is twofold. First, to get steerer output; second to get a working relationship between steerer output and equivalent tiller length. To obtain the equivalent tiller length, divide the output figure by 40. For example: a boat with a 24" wheel and a 12" quadrant has an output of 432 ft. lbs. Divided by 40, this equals the leverage of an 11 foot tiller. It is interesting to note that a 30" wheel with an 8" quadrant has the identical output of a 20" wheel with a 12" quadrant the difference being the number of turns. The first with 1.8 turns has fast action and a large wheel (the preference of most racing skippers). The second with 2.7 turns has a slower action and a smaller wheel (for the boat used primarily for cruising). Which do you prefer? We can fit the steering action to your boat. WHEEL TURNS LOCK TO LOCK OUTPUT FORMULA To determine the number of turns of the steering wheel from hard over to hard over, divide the chain travel of the sprocket into the quadrant arc. Our experience indicates most boats are set up for 70˚ to 80˚ of rudder travel. Taking the standard 5⁄8-11 tooth sprocket with a travel of 6.9" per turn and divide it into the selected (10") quadrant with 80˚ of travel (14.0") and the steering system will have 2.03 turns of the wheel. The larger pitch diameter sprockets with a given quadrant will result in fewer turns of the wheel. The output figures below are based on the following formulae: Mechanical advantage = Rw x Rq where Rw = wheel radius (inches) *1.1 and Rq = quadrant radius (inches) *1.1 for 5⁄8" – 11 Tooth Sprocket 1.2 for 3⁄4" – 10 Tooth Sprocket 1.3 for 5⁄8" – 13 Tooth Sprocket 1.6 for 3⁄4" – l3 Tooth Sprocket 1.5 for 5⁄8" – 15 Tooth Sprocket TYPICAL PEDESTAL STEERER SYSTEM A complete Pedetal Steering system will consist of the following items: 1. Pedestal 2. Steering Wheel 3. Chain and Wire Rope Assembly 4. One Pedestal Idler or Conduit Bracket *5. Two Sheaves or Sheave Bracket 6. Quadrant or Drive Wheel (using Radial Drive Steering System eliminates #5) 7. Two Wire Take-Up Eyes 8. Four Pedestal Mounting Bolts 9. Four Wire Rope Clamps 10. Stuffing Box (if required) Note: For Pull-Pull Systems eliminate item #5 and substitute the appropriate length of Part No. 797 conduit. *The number of sheaves will vary for mid-ship cockpits, or particularly complicated aft cockpit arrangements. For complete warranty information, see inside front cover. CHAIN SPROCKET DATA Pedestal Chain Sprocket Chain Travel Steerer Pitch No. of Pitch Dia. per turn of wheel 334-335-400 In. Cm. Teeth In. Cm. In. Cm. Standard 5⁄8 15.8 11 2.2 5.6 6.9 17.5 SPECIAL ALSO 5⁄8 15.8 13 2.6 6.6 8.2 21.0 AVAILABLE 5⁄8 15.8 15 3.0 7.6 9.4 24.0 FROM STOCK 3⁄4 19 10 2.4 6.1 7.6 19.4 CHAIN TRAVEL HARD OVER TO HARD OVER Quadrant or Radial Radius in Inches ARC 6.5 8 10 12 14 16 18 20 24 30 36 90˚ 10.2 12.6 15.7 18.9 21.9 25.1 28.3 31.4 37.7 47.1 56.5 80˚ 9.2 11.2 14.0 16.7 19.4 22.3 25.1 27.9 33.5 41.9 49.5 70˚ 8.2 9.8 12.2 14.7 17.1 19.6 22.0 24.4 29.3 36.7 43.4 *Note: Turns of wheel output are based on using 5⁄ 8"-ll tooth sprocket. Quadrant Steering Pedestal *Turns of Length of Output Equivalent Length of or Drive Wheel & Compass Wheel, Lock Roller ft lbs Tiller Required Idler & Required Wire Waterline Wheel Size Size Size to Lock Chain (40 # Length Sheave Size Rope Size (L.W.L.) In. In. In. Cm. 70˚ 90˚ Ft. Cm. Input) Ft. Cm. In. Cm. In. Mm. (17-23) 6.5 18-22 334-4 10.2 1.0 1.2 11⁄ 2 46. 181 41⁄ 2 137. 4 10.2 3⁄ 16 4.76 (17-25) 8 18-22 334-4 10.2 1.4 1.8 11⁄ 2 46. 264 6 182. 4 10.2 3⁄ 16 4.76 (26-29) 10 24-28 335-5 12.8 1.7 2.3 2 61. 368 9 274. 4 10.2 3⁄ 16 4.76 (30-34) 12 26-30 335-5 12.8 2.1 2.8 2 61. 503 12 365. 4 or 6 3⁄ 16 or 1⁄ 4 (33-34) 14 26-30 335-5 12.8 2.4 3.0 21⁄ 2 76. 596 15 457. 4 or 6 3⁄ 16 or 1⁄ 4 (34-35) 16 32-36 400-6 15.4 2.8 3.5 21⁄ 2 76. 720 18 548. 6 15 4 1⁄ 4 6.35 (37-40) 18 32-36 400-6 15.4 3.1 4.0 3 91. 820 20 609. 6 15.4 1⁄ 4 6.35 (46-55) 20 36-40 400-6 15.4 3.5 4.5 3 91. 1080 25 762. 8 1⁄ 4 6.35 (56-70) 24 36-40 400-6 15.4 4.2 5.4 31⁄ 2 106. 1540 38 1158. 10-12 20.5 1⁄ 4 6.35 (60-75) 30 40-48 400-6 15.4 5.3 6.8 41⁄ 2 140. 1727 43 1310. 10-12 25.4 5⁄ 16 7.94 Values in chart are for 5⁄ 8" – 11 tooth sprocket QUADRANT SIZES (inches) No. of Turns 6.5 8 10 12 14 15 16 18 20 24 30 36 90˚ 1.3 1.8 2.3 2.7 3.2 3.4 3.6 4.1 4.5 5.5 6.8 8.2 18 178 217 272 326 381 408 435 490 544 653 817 980 20 196 240 307 360 426 453 480 548 600 735 890 1096 22 216 264 338 396 469 496 528 601 660 806 997 1202 24 236 288 368 432 512 539 577 656 720 880 1088 1312 26 312 398 478 555 582 624 711 780 953 1178 1422 28 336 429 503 596 623 671 764 839 1025 1268 1528 30 360 460 540 640 667 720 820 900 1100 1360 1640 32 384 490 576 682 709 768 875 960 1174 1452 1750 34 408 521 612 725 752 816 928 1020 1247 1542 1926 36 432 552 648 768 795 864 984 1080 1320 1632 1968 38 458 578 687 808 835 916 1038 1145 1386 1724 2076 40 484 605 726 847 874 968 1089 1210 1453 1816 2178 44 532 666 799 932 959 1065 1198 1332 1598 1998 2396 48 581 726 871 1017 1044 1162 1307 1453 1743 2179 2614 54 648 817 981 1144 1171 1308 1471 1635 1961 2452 2942 60 727 908 1090 1271 1298 1453 1635 1816 2180 2725 3270 64 775 969 1162 1356 1383 1550 1744 1937 2325 2906 3488 72 872 1090 1308 1526 1553 1743 1962 2180 2616 3270 3924 Wheel Diameter (inches) Pedestal Steerer Installation Guide Edson International 146 Duchaine Blvd., New Bedford, MA 02745-1292 • tel (508) 995-9711 • fax (508) 995-5021 Edson’s Pedestal Installation Guide has been written to assist the boat owner, boatyard, and the designer in making the most convenient pedestal installation for any given cockpit design. Before making a final decision on the location of the steerer it is always a good idea to make a dummy steerer out of a 2 x 4, a short length of broomstick handle for the shaft and a cardboard or plywood cutout of the wheel size. At the same time the area below the cockpit floor should be checked for obstructions such as tanks and lines; also check if the builder installed cockpit floor reinforcing and its location. The location of the winches and the helmsman’s visibility should also be noted. Illustration 1 shows a steerer forward using Radial Drive. By placing the steerer at the forward end of the cockpit the helmsman has the protection of the companionway dodger and has quick and easy access to the cabin below. The forward location also keeps the cockpit activity aft of the helm and, in shorthanded situations, allows the helmsman to steer uploads/s3/ steering-guide.pdf