Taking Care of Your Hydraulic Steering


What you should know about this often overlooked marine system.

In its most basic form, hydraulic steering is made of up three components: a pump with an integral reservoir for hydraulic oil, a ram that connects to a rudder (or outboard engine), and connecting lines that transmit inputs from the steering pump to the steering ram. It is very simple, really, and when sized and installed correctly, makes for a mostly forget-about-it system. Turn the steering wheel in either direction pumps oil through the lines to the ram, which in turn pulls or pushes the rudder or outboard or sterndrive in the desired direction. There is not much to it and the system just works.

For the most part, ignoring one’s hydraulic steering will not cause a catastrophic loss of steering. But at the very least, you should inspect it once a year. With proper care, a hydraulic steering system will last a very long time.

The simplest example of hydraulic steering is found on small powerboats powered by single outboard or multiple engines linked by a tie bar. The center console is one of these, the virtual sport utility vehicle of boating, perfect for a wide range of activities afloat. Steering systems get progressively more complicated on larger boats with multiple helms, autopilots and power steering, but the basics are much the same. So, too, is the maintenance.

Look at the seals on the ram. The shaft should never be wet. If it is, wipe it dry with a rag and check it again as you turn through a steering cycle. If a wet shaft comes out of the ram, the seals are leaking and need to be replaced.  Check to see there is no pitting on the shaft as well, a sign of corrosion that will ultimately cause hydraulic fluid to leak out of the cylinder.


Remove the vented cap on the hydraulic reservoir at the helm and take a sample of the hydraulic oil. Does it look black? Does it smell? Hydraulic steering fluid is clear, mostly odorless and slightly colored. It is specially formulated with viscosity stabilizers, anti-wear and anti-foaming agents, and corrosion inhibitors. It is the best oil to use in hydraulic steering systems. (Any oil that meets MIL 5606 specification can be used, and in an emergency, even 5W engine oil.)

If the hydraulic steering oil sample contains dirt or is otherwise contaminated, the entire system should be flushed and the hydraulic oil replaced.

Abrasive dirt is the biggest killer of hydraulic systems, and often comes from debris during the initial installation of the steering system. Dirt or “dust” can enter the system when hoses are cut and fittings installed. It is always best to flush out a steering system before the final hydraulic oil goes in, something to consider when making a repair.

Many marine professionals recommend that the system be flushed out and oil replaced every five years, making sure to bleed the system to remove air bubbles. Many service yards use portable purging systems that make this a quick and foolproof job that takes just minutes.

Spend a moment at the helm. Is there any oil visible around the seals behind the wheel? Does the wheel feel spongy when it is turned? It may have air in the system which needs to be bled out. If the system was previously purged and all air removed from the lines, this may be a sign that there is a leak somewhere. A spongy wheel may also indicate the ram or steering pump is leaking internally, evidence of which you may not readily see. If you once enjoyed three-and-a-half turns lock to lock and now it is five turns, you have a leak somewhere.


Oil does not evaporate, nor is it consumed by use. So if you have to add oil to the reservoir, you have a leak somewhere.

Check the hoses and connections between the helm and the ram with a clean rag at least annually. Is there any wetness at the connections? The nylon plastic hoses that snake their way aft to the steering ram can get brittle and crack over time, although they typically are protected from the elements for this reason. It is the flexible rubber hoses that are most exposed, but also easy to inspect.

On bigger boats this yearly inspection takes a bit more time, but the process is the same. The components of hydraulic steering are mostly trouble free until they are damaged or they wear to the point where seals break down.

Electronic steering is a perfected technology and is the direction of the industry. An electronic helm steers the boat through fly-by-wire signals to turn a pump on and off, and the hydraulics are now considered the “back end” of the steering system. Drastically shorter hydraulic lines are well protected near the rudders or engines, controlled by signals transmitted by wire from whichever helm is operational. Power steering has become commonplace, and today even the autopilot is a plug and play affair. Adding a second steering station is simply another set of wires to be run, nowhere near the complexity of traditional hydraulic steering.

Traditional hydraulic steering companies see recreational boating moving away from fully hydraulic steering systems in favor of the greater control and flexibility of electrohydraulic steering. In fact, some well-known companies no longer recommend replacing parts in any steering system older than 10 years. As rubber ages, seals wear out, and system components get hard and brittle, companies like SeaStar now think it prudent for boat owners to consider replacing and/or upgrading their steering system to one of the newer solutions that use electronics. Undertaking such a project is not difficult, and is a viable solution for anyone with steering issues on an older boat.

So for all of the owners of those older Taiwan trawlers built in the '70s and '80s, it is very much within the realm of a DIY project. In fact, these boats are prime candidates for upgrading from older hydraulic or mechanical steering.