There are two basic parts to a hydraulic system: the helm and the cylinder. More complicated systems may have fluid reservoirs, specialized valves, relief valves, autopilot pumps, etc. The helm consists of a hydraulic pump and a system of valves, which pumps fluid into the hydraulic lines. The pump is activated by turning the steering wheel, which causes a “swash plate” to press on a series of small piston pumps. The use of small pistons and ball bearings makes the pump action very smooth – nothing like a normal piston pump. The internal valve assembly acts as a check valve, preventing the outgoing fluid from returning, while effectively eliminating kickback to the wheel. In systems like the popular Teleflex SeaStar and SeaStar Pro, the helm serves several functions, incorporating a hydraulic fluid reservoir and a relief valve as well. Some systems have a helm, reservoir and relief valve as separate components.

In use, a clockwise turn of the steering wheel will send fluid from the Helm Unit into the starboard hydraulic line. This fluid will be pumped into the cylinder and either extend or retract the cylinder rod. Incoming fluid pushes a piston which is pinned to an external rod. As the piston is moved the rod is either extended or retracted, and the boat turns. Outgoing fluid from the other end of the cylinder is returned to the helm via the port side line.

Selection of the proper components is relatively easy, since the number of components is limited. Select the SeaStar 1.7 helm for boats to 40’, outboard engines with up to V-6 engines, and speeds to 50mph. For boats with larger outboards to 300hp and speeds over 60mph, select the SeaStar Pro. It operates at pressures up to 1,500psi, and offers the best steering control and reduced wheel walk and chatter. Its increased 2.0cu.in. displacement provides faster steering response, with slightly higher helm effort. The SeaStar regular helm is available in 2.0 and 2.4cu.in. displacements for boats with larger cylinders or special needs by Special Order.

The current generation of outboard-mounted cylinders makes installation easy, since they use the tilt tube of the engine for support, and act directly on the engine‘s steering attachment point. In other words, the cylinder acts between two points on the outboard, and exerts no force on the boat‘s hull or deck. This type of cylinder is what is known as a balanced cylinder, meaning that port and starboard deflections take the same amount of hydraulic fluid. This, in turn, makes it ideal for autopilots, since they act symmetrically port and starboard. Note that some older BayStar steering kits (HK4200 and HK4230) use an unbalanced cylinder, and cannot be used with autopilots. There are a wide variety of inboard and sterndrive cylinders available to fit practically any boat, but selecting the right ones can be tricky. Teleflex offers extensive technical help at their web site, www.seastarsteering.com, which will guide you step-by-step through the selection process. And, of course, please contact us if you need more information.