SeaStar Hydraulic Steering System for Outboard Install

Upgrading your boat’s outboard steering with a SeaStar hydraulic steering system improves the craft’s running and handling characteristics. 

Boat hydraulic steering system

What’s more, a hydraulic steering upgrade is a straightforward job that requires very little maintenance and that most boat owners can take care of themselves.

A variety of SeaStar hydraulic steering system kits exist that have their own specific installation procedures. However, here’s a basic guide to installing an outboard SeaStar hydraulic steering system.

NOTE: Reading the SeaStar manual and following it precisely is how a proper installation should be done. This guide only serves as a basic installation guide for people who don’t have the manual available.

SeaStar hydraulic steering kit

SeaStar steering wheel

Remove the Mechanical Helm

Remove the steering wheel and the helm steering unit, followed by the steering cable from the helm unit. Usually the steering wheel has a woodruff key on the steering column that’s easy to lose when removing the steering wheel, so keep an eye out for the key flying off as you break the wheel loose.

Remove the Mechanical Steering

Disconnect the drag link from the steering cable, then remove the drag link and pull the steering cable from the tilt tube, and remove the steering cable. Thoroughly clean the inside of the tilt tube, remove any old grease, then inspect the inside of the tube for corrosion and re-grease it. It’s generally easier to pull the steering cable through and out from the aft end than to try and pull it out from the helm. With the old steering removed, swing the engine side to side to make sure it pivots freely. If it doesn’t, the pivot tube will need cleaning and degreasing. 

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Install the Hydraulic Steering 

Connect the SeaStar hydraulic steering cylinder to the tilt tube and the tiller arm. The new hydraulic kit should include a tiller bolt and nyloc nut. Also, the tiller bolt and nut are the only components that keep the outboard in place. If the tiller bolt and nut were to come loose at full speed, the propeller torque would snap the engine to full steering lock in an instant. 

Install the Hydraulic Helm

Usually it’s necessary to drill new holes for the SeaStar hydraulic helm’s mounting bolts, and it may be necessary to cut a wider central hole for the helm to fit through. Most kits come with a paper template to simplify the cutting and drilling process. Always measure twice and cut/drill once. It works out far quicker to take a minute to get the template in the precise spot than it takes to guess things and end up having to drill or cut multiple holes.

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Install the SeaStar Hydraulic Lines

Connect the hydraulic lines to the helm unit. SeaStar helms are marked P for port and S for starboard. It may be easier to connect the hydraulic pipes to the helm before the helm is attached to the dash. Keep the hydraulic lines’ end caps on until the moment they’re ready to be connected to the helm or cylinder. This prevents any debris from entering the pipes. Once the helm is installed, reattach the steering wheel.

Connect the hydraulic lines to the steering cylinder. Be sure there’s enough extra line for the outboard to travel from steering lock to steering lock without pulling or stretching the lines.

SeaStar hydraulic lines diagram

NOTE: Never use Teflon tape on the helm’s hydraulic pipe connectors, because the tape will get into the hydraulic fluid and cause the system to fail. 

Make sure the hydraulic lines are connected to the correct side of the steering cylinder. SeaStar’s side mount systems run port (helm) to port (cylinder) and starboard (helm) to starboard (cylinder). However, its center mount systems run port (helm) to starboard (cylinder) and starboard (helm) to port (cylinder).

Bleed the Hydraulic System

Connect a fill pipe to the helm unit and bleed pipes to either side of the steering cylinder. Add hydraulic fluid to the helm and open the bleed valve on either the port or starboard side of the cylinder.

SeaStar hydraulic steering fluid

SeaStar hydraulic helm fill kit

Turn the wheel in the direction of the open bleed valve, and keep turning until there are no more bubbles in the fluid being bled from the cylinder. Close the bleed valve and repeat the process for the other side of the cylinder.

Continue topping off the fluid going into the helm. If air gets into the “fill” end of the system, the whole system must be bled through until the air is removed. 

PRO TIP: Although bleeding the system can be done single-handedly, it’s much quicker with two people, as there’s less likelihood of air getting into the system if one person is at the helm and the other at the cylinder.

Check the Hydraulic Steering System

Rotate the wheel and observe the outboard. Turning the wheel should result in an immediate response in engine movement. A delay or excessive play, or weak or spongy steering means there’s still air in the system. Check the hydraulic connections and the steering cylinder seals for leaks by turning the wheel from full lock to full lock and trying to turn it beyond the locking points. This should put maximum pressure on the hydraulic system. Inspect all hydraulic connections and steering cylinder seals for any signs of leaks.

PRO TIP: Check the hydraulic steering system before returning the boat to the water. It’s much better to find a loose connection on land than to have a hydraulic failure out on the water.

Boat hydraulic steering

Enjoy Your Hydraulic Steering Upgrade

A hydraulic steering upgrade is worth the time, effort and money you put into it. Depending on how bad your old mechanical steering system was, any steering bias should have been minimized, and there’ll be no torque steering during hole shot. The biggest noticeable gain will be how effortless it is to steer.