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Steering straight

Jun 25, 2014
Flybridge steering station on a power voyager. Without sails to help balance the vessel, steering systems must be highly reliable.

Flybridge steering station on a power voyager. Without sails to help balance the vessel, steering systems must be highly reliable.

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The hydraulic steering installed on your power voyaging boat is one of the most reliable systems aboard. To “dial-in” your trawler steering there are some fundamentals you should understand and a few key components you should monitor as part of your regular maintenance routine; oil reservoir, hydraulic cylinder, hydraulic ram, tiller arm, oil manifold, rudder post, rudder bearings, etc.

Most sailboats can balance the helm through sail trim resulting in a light steering touch and the hull shape is designed to still hold course when heeled over. Trawlers have no such natural force to assist with directional guidance and trawler hull shapes are “boxier,” they run more upright and may have additional appendages dragging (like active fin stabilizers, skegs and fixed propellers) making trawler hull forms less “fluid” through the water.

Unless you’ve had a problem with your steering system, you may not have given this much thought, but naturally the ability to turn your trawler with a responsive helm is an essential attribute! Trawlers rely on the natural water flow (technically the turbulence of propeller wash) across the rudder(s) to maneuver.

Rudder post with tiller attached to steering ram. Note padded rudder stops and two autopilot sensors.

One of the first boat handling tricks many of us learn is to back-and-fill — hard over rudder and then a series of main engine gyrations shifting from forward to neutral to reverse — with a little throttle boost now and again — to get the hull rotating in a circular motion. Think of your rudder as a deflector and remember, unlike a car that turns via the front tires, you are really turning the stern to change course. When backing in reverse you may experience prop-walk to port or starboard. It’s a good idea to practice so you can anticipate your direction of travel. Bow and stern thrusters can be very helpful in close-quarter maneuvering, but for a trip outside of the harbor of any distance you really need the ability to steer straight and track on course using your rudder(s).

As you spin your steering wheel, (in the pilothouse or on the flybridge), the hydraulic gear pump sends pressurized hydraulic oil as a force in one direction or the other to actuate the ram housed in the steering cylinder. The ram, which acts like a piston that pushes or pulls, is attached to a stout horizontal tiller arm clamped on top of the vertical rudder shaft which correspondingly rotates the rudder(s) to port or starboard. Cylinders and rams are typically mounted horizontally on top of the rudder bearing support post. It is vitally important that the ram is not restricted by loose items in your lazarette that could shift while underway and interfere with this constant movement.
 

Air pressurized

Most of these steering systems utilize a hydraulic oil reservoir with small sight level “windows” to show how much oil is inside. They are air pressurized via a Schrader valve (bicycle inner tube type). The closed-loop system of hoses and valves is driven by the helm pump which sends the oil to move the ram.

Rudder bearing mounted above, rudder tube coupling below.

If your steering feels sluggish, the first place to look is the air pressure analog gauge on top of the reservoir. If the needle is below the normal settings, a few strokes with a simple bicycle pump (a tool you should have on board and keep near the reservoir) will help you regain the force you need to get back on track. Be sure to regularly (before leaving the dock) inspect the pressure gauge on top of the reservoir as air leaks are not uncommon.

Well designed steering systems include a hydraulic oil steering manifold near each rudder (single vs. twin) and this manifold will have a bypass valve so that you can disable the hydraulic oil loop and turn the rudder post head manually with your emergency tiller. The operational components (bypass valve, emergency tiller fitting, etc.), should be sourced, labeled and understood before you leave the dock. Using an emergency tiller will provide steering that is better than nothing (barely) so take a look at how your trawlers’ back-up steering system is designed. Consider a block and tackle apparatus to help you actually control and leverage the emergency tiller so that you will be able to turn your trawler if you get into difficulty. Actual hand steering using your emergency tiller can be very difficult and fatiguing, it may be wise to weld a ring on the tiller end for attaching lines.

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