Even the simplest tiller system requires maintenance from time to time. You should check for free rudder movement. Is there any play in the fittings between the rudder, rudder stock, and the tiller itself? If the tiller is made of wood, you should remove it from the tiller head and look for any signs of rot. Is the wood at all soft? Has the hole enlarged around the bolt? While you're at it, this might be a good time to take a moment to come up with an emergency steering plan should the tiller ever break.
All boats that are wheel-steered should have an emergency steering tiller on board. If you have never used your emergency tiller, I highly recommend that you pull it out, fit it to the rudder head, and make sure that it can actually steer the boat. That way, if you ever encounter a real steering emergency, you'll know how it all goes together.Engineers have devised numerous ways to transmit movement from the steering wheel to the rudder. This transmission is generally geared so that rudder forces on larger boats won't be too much for the average sailor to handle comfortably. There are four common types of steering systems: direct linkage, chain and cable, enclosed cable, and hydraulic.
Direct Linkage Systems Two systems couple the wheel shaft directly to the rudder head: rack and pinion and worm gear. These designs are simple, robust, and powerful. They are easy to identify because the mechanism is right under the helmsperson's seat, with the wheel shaft facing forward. The general rule of care for these systems is to keep the mechanism clean and well greased. These systems are usually fitted with grease zerks at the wheel shaft and other bearings. After long use, the bearing surfaces may wear and eventually need to be replaced. In some rare cases, the bearings may bind, creating very stiff steering. Loosening all the adjustment bolts and allowing the mechanism to realign itself generally solves this problem.
Other direct-linkage systems use a set of bevel gears for the horizontal wheel shaft to turn a vertical shaft inside a pedestal. The vertical shaft and the rudder shaft each have a bell crank, or tiller arm, which are tied together with a solid rod or bar. The tie rod has a turnbuckle for length adjustment, along with a ball and socket, or swivels, at each end. Older Whitlock Cobra systems are good examples, and the brand-new Edson CD-I is a unique combination of a rack-and-pinion gear housed in a modern pedestal.
Chain-and-Cable Systems Most wheel-steered boats use a chain-and-cable steering system. Whether the wheel mechanism is attached to a bulkhead, enclosed in a console, or mounted to a pedestal, these systems have a gear fastened to a horizontal wheel shaft. A short length of roller chain rides on the gear and attaches to two cables that then run through pulleys until they reach the rudder. The cables pull the rudder to port or starboard through a quadrant, or radial-drive wheel, fastened directly to the rudder shaft.
Because they have so many moving parts, chain-and-cable systems require more maintenance. The most critical wear point is the cable itself. Examine the flexible wires inch by inch. Look for broken strands, crushed spots, or badly rusted areas. The terminals that attach the wires to the chain are usually swaged and subject to bending and cracks. Examine the gear, chain, and the clevis and cotter pins that attach the chain to the wire cables inside the pedestal. If the wires are suspect, replace them, or at least carry spares for quick installation if the originals should fail.
The ends of the wires are usually attached to the quadrant with cable clamps that can loosen and then damage the cables. The wires do not need to be bar tight but must be firm to avoid jumping off the sheaves. They are usually tightened at the simple eyebolt at the back of the quadrant. Inspect the bolts holding the quadrant and ensure that it is firmly attached to the rudder stock.
Complex systems have up to 10 turning sheaves and each one must lead fair. Have a crew member turn the wheel while you watch the wire pass over each sheave. It should enter and exit each turning block without touching the edges of the sheave itself. Check each block for loose mounting bolts and worn pins. Cleaning and greasing them helps reduce friction and steering effort. If the system is very old, it may be wise to remove the cable and disassemble each sheave assembly for closer inspection.
Enclosed-Cable Systems Cables traveling through sheaths or conduits are often used to steer boats with outboard rudders, or when the interior layout interferes with direct-cable runs. These can be a single-cable system called a push-pull, or two cables dubbed as a pull-pull system. A few are hybrid chain-and-cable systems from the pedestal down to an obstruction that requires a sheathed cable. These systems require the same maintenance as for a chain-and-cable system with the added requirement that the sheathed cable requires periodic renewal. If the steering system of an enclosed cable system becomes stiff, the cable should be the first suspect.
Hydraulic steering is generally simple and reliable with the only requirement being to keep the fluid and pressure inside the system. As seals wear, hydraulic oil leaks at the steering shaft or the output cylinder do occur. Occasionally, an unsecured hydraulic line will chafe causing a leak. Monitor the pressure and fluid levels and repair leaks as they occur.
Remember, an annual steering-system check up will keep those wheels turning freely.
Last edited by administrator; 02-10-2009 at 04:30 PM.
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