Edson Chain & Wire Steering Systems — Planning, Installation & Maintenance Guide

Planning & Sizing

• Cruising and offshore: a larger quadrant with more output and more wheel turns hard over to hard over. Racing: a smaller quadrant, fewer turns and a larger wheel for faster action. Final recommendations must be approved by your naval architect.
• Equivalent tiller length = output (ft lbs) ÷ 40. Example: 24" wheel and 12" quadrant = 432 ft. lbs = an 11 foot tiller. A 30" wheel with an 8" quadrant has the same output as a 20" wheel with a 12" quadrant: 1.8 turns (fast) versus 2.7 turns (slower, smaller wheel).
• Wheel turns lock to lock = quadrant arc ÷ chain travel per turn. Most boats are set up for 70° to 80° of rudder travel: the standard 5/8-11 tooth sprocket (6.9" per turn) with a 10" quadrant at 80° (14.0") gives 2.03 turns. Larger pitch diameter sprockets give fewer turns.
• Mechanical advantage = Rw × Rq ÷ factor (Rw wheel radius, Rq quadrant radius, inches): 1.1 for 5/8"-11 tooth, 1.2 for 3/4"-10 tooth, 1.3 for 5/8"-13 tooth, 1.6 for 3/4"-13 tooth, 1.5 for 5/8"-15 tooth sprocket.
• A complete system: pedestal, steering wheel, chain and wire rope assembly, one pedestal idler or conduit bracket, two sheaves or sheave bracket (not with radial drive or pull-pull, which uses Part No. 797 conduit), quadrant or drive wheel, two wire take-up eyes, four pedestal mounting bolts, four wire rope clamps, stuffing box if required.

Typical installations (5/8"-11 tooth sprocket)

Chain sprocket data (pedestal steerers 334-335-400)

Chain travel hard over to hard over (inches)

Steerer output chart (ft lbs) – wheel diameter vs quadrant size

Values for the 5/8"-11 tooth sprocket. On request Edson supplies data sheets and recommendations for your boat from construction drawings or sales literature.

Locating the Pedestal

• Mock up the steerer first (a 2 × 4, a broomstick for the shaft, a cardboard or plywood wheel); check under the cockpit floor for tanks, lines and reinforcing, and check winch handling, helmsman's visibility and main sheet clearance.
• Forward (radial drive or quadrant and sheaves): helmsman protected by the dodger; with a bridge deck, a large wheel within 2" or 3" of the cockpit seats; fit a pedestal guard as a handhold.
• Mid-cockpit: keep at least 15" (38 cm) clearance from the bridge deck or companionway.
• Aft: keep at least 16" (41 cm) behind the wheel for foot room; watch the backstay and the main sheet.
• Suggested at least 21" (53.3 cm) from the pedestal base (dead centre aft) to the rear of the cockpit for standing room. Mark the four bolt holes with template EB237 and drill only a 1/16" (1.6 mm) centre hole until the layout is confirmed.
• Transom-hung rudders with pull-pull: Part No. 612 quadrant – 10 inch (26 cm) for 20-36 ft (6-11 m), 14 inch (36 cm) for 37-45 ft (12-14 m), 20 inch (50 cm) for 45-60 ft (14-18 m); a very hard-to-steer boat goes one size up. The 10" quadrant needs a transom hole of about 2" (5 cm) by 6" (15 cm), booted or drained.
• Midship cockpits: wire via Part No. 607 idler and bulkhead-mounted sheaves, or pull-pull conduit (boats up to about 60'); larger boats must use Part No. 881 conduit idlers at high load points. Part No. 908 reversible sheave bracket and Part No. 824 bracket carry built-in rudder stops.

Rudder Stops and Emergency Steering

• Every quadrant or radial drive system needs rudder stops able to take all rudder loads hard over; most sailboats limit total travel to between 80° and 90°. Stops must hit squarely and as close to the drive as possible; use the reinforced rubber piece supplied with the radial drive.
• For offshore, commercial and charter use, and with a large wheel, small quadrant and large rudder, use an independent stop such as a tiller arm.
• Never back down at speed and let go of the wheel; tie off or brake the wheel when the boat is unattended.
• Provide emergency steering (existing tiller head or a made-up emergency tiller) and practise it regularly. Check the tiller head fitting is not the thrust bearing before modifying the post. Milled pedestal bases (Part No. 690 or 714) give room for an emergency tiller.

Maintenance

• Remove the compass (tape it for realignment, then check its accuracy). Grease the needle bearings with Edson Part No. 827 Teflon lubricant through the holes on top of the bearing housings while spinning the wheel; do not over-grease (it runs onto the brake pads).
• Oil the chain with #30 weight motor oil; do NOT grease the chain.
• Oil the wire through a few tissues in your palm: a torn tissue flags a broken strand. Replace a damaged wire immediately (Part No. 775 wire and chain replacement kits) and replace the wire after 5 years.
• Inspect the system at least once a year under load: under power, hard over at full throttle, with someone below watching for bending or creaking.
• Clean the pedestal with soap and water, never MEK or acetone; polish stainless with an abrasive cleaner. In the tropics or in charter service speed up the schedule; on passages inspect daily and lubricate weekly.

Shaft removal (models 334/335 and 400)

1. With wheel and brake removed, replace the wheel nut with a standard 3/4" or 1" hex nut.
2. Back off the take-up eyes, lift the chain off the sprocket and tie it forward in the bowl; put a cloth under the sprocket.
3. Align the notch in the aft nylon washer with the “V” on the sprocket, drive the pin out of the sprocket (round end toward grooved end).
4. With wood against the hex nut, tap the shaft out; remove sprocket, nylon washers and needle bearings; clean. Reassemble in reverse and grease only after reassembly; check the compass.

The breakdown labels include A-595 bearing liner, A-95A drive pin, 855-2-11 sprocket, A-140-1.1 needle bearing, A-137 nylon washer, A-327 O-ring, A-729 washer, A-660 snap ring, B-171 wheel shaft key, B-250 wheel shaft (400) and B-273 wheel shaft (334/335), brake assembly Part No. 689. When ordering give the pedestal serial number, part number, part name and quantity.

Annual Steering Inspection (EB-372-14)

• Wheel/shaft: inspect wheel, key, nut and snap ring (straight shaft, side-mount brake, pre 2003) or wheel, key, nut and brake knob (tapered/thru-shaft brake, 2003-present). Coat 3 1/2" compass bolts with Tef-Gel when refitting.
• Brake: tighten to test, inspect pads, clean grease off the knurling or plate.
• Chain and sprocket, shaft bearings (turn the shaft with the chain off), steering cables (run a cotton ball along the wire), cable tension (check the lazy cable hard over), conduit (replace if worn or older than 10 years on saltwater boats), sheaves/idler, alignment, quadrant or radial drive and rudder stop, pedestal bolts and base sealing.
• Once to twice a season is the bare minimum; racing and heavily sailed boats, and boats in the Caribbean or equatorial waters, need more frequent inspections.