Check Your Steering System Before Buying an Autopilot

Why the steering system decides the autopilot

An autopilot holds a boat on a chosen heading by moving the rudder, and it does that through the boat's existing steering system. The drive unit, whether it is a tiller drive, a wheel drive, a hydraulic pump, a linear drive or a rotary drive, is the part that connects to that system. So the type and condition of the steering decide which autopilot pack can fit your boat. The drive types explained article covers what each drive name means.

Raymarine's drive unit page describes the drive as the part that interfaces with the vessel's steering system to keep the boat on the right course, and it lists drives for hydraulic, mechanical and power-assisted steering. Pack titles usually name the steering they are built for, for example EV-100 Tiller, EV-100 Wheel Pilot and EV-100 Power Pilot, and this site's marine autopilot buying guide explains how those titles read. When the steering itself is healthy, the drive has a clean connection to work with. When it is worn, the drive has to overcome the wear.

This article explains three things boat owners can check in plain words: friction, backlash and hydraulic cylinder health. None of this replaces the maker's manual or a qualified installer, and this site gives no installation instructions. The goal is to help you read a listing with your steering system in mind.

Friction: how heavy the helm feels

Friction is the resistance you feel when you turn the wheel or push the tiller. Some resistance is normal in any steering system, and a well-maintained system moves smoothly from lock to lock. A helm that feels heavy, stiff or sticky is a sign that the moving parts are working against extra resistance.

At the dock, turn the steering lock to lock and watch how the rudder moves. Note how much effort the helm takes and whether the movement is even. If the effort is uneven or very heavy, that is a question for a qualified installer or an authorized dealer before you order an autopilot. A drive unit can move the rudder, but it cannot repair a steering system that binds.

Backlash: the slack before the rudder moves

Backlash is the loose play you feel at the helm before the rudder begins to move. If you turn the wheel a little and nothing happens, the slack in the cables, chain or linkage is taking up the movement. That play is wear, and a drive unit has to take it up before it can move the rudder.

A steering system with noticeable backlash makes an autopilot's corrections less steady, because part of each correction disappears into the slack. A qualified installer can inspect the linkage and tell you whether it needs adjustment or replacement. That check belongs before you decide whether a complete autopilot pack or a core pack is the better choice, and the retrofit considerations article covers the wider question of replacing an older system.

Hydraulic cylinder and fluid health

On a boat with hydraulic steering, the autopilot drive is often a hydraulic pump that moves fluid to the steering cylinder. The condition of that cylinder and the fluid decides how well the drive can move the rudder. Look for leaks, low fluid and air in the system. Puddles, stains around the ram and a spongy feel at the helm all point to a problem.

A hydraulic system in good order lets the steering move smoothly and evenly. A system with air or a leak makes the helm feel soft and can leave the autopilot drive without a firm connection to the rudder. Raymarine's drive unit page advises boat owners to consult an authorized dealer when they are not sure what type of steering is installed, and the same advice applies when a hydraulic system shows signs of wear. The hydraulic autopilot guide and the hydraulic steering explainer cover the pack choices.

What the check means for the pack you order

A complete autopilot pack includes the drive unit in the box. A core pack leaves the drive out, for boats that keep an existing drive. If your steering is worn and you plan to keep the existing drive, ask whether that drive can still do its job with the wear in the system. A worn steering system makes the drive work harder than it should, which is a question for a qualified installer.

On this site, the drive in the box is a stated detail, so you can filter for packs that include a drive and packs that do not. The complete packs guide and the core packs guide compare those stated details. The core pack without drive article explains why a buyer might choose no drive in the box.

Questions to ask before you order

Before you order, write down what steering the boat has: tiller, wheel, hydraulic, cable or steer-by-wire. If you do not know, the boat's manual is the place to look, or ask an authorized dealer. Raymarine's drive unit page says to consult an authorized dealer if you are not sure how to determine the type of steering system installed on the vessel.

Then ask the questions that matter to the drive:

• Does the helm move evenly from lock to lock, without heavy or sticky spots?
• Is there play in the wheel or tiller before the rudder moves?
• Are there leaks or stains around the helm, the hydraulic cylinder or the hoses?
• For hydraulic steering, is the fluid at the correct level and free of air?
• Has the steering system been inspected recently by an installer or dealer?

Match the check to your steering type

The same check looks different on different steering. Tiller steering: the friction and play in the rudder stock and the tiller mount. Wheel steering: the slack in the wheel cables and the wheel drive. Hydraulic steering: the cylinder and fluid. Steer-by-wire: the electronic helm system, which needs a pack built for that system. The tiller steering explainer and the steer-by-wire explainer cover those two cases.

A healthy steering system is the starting point, and then the guide compares the stated details of the packs themselves. This site's marine autopilot reviews compare listings on stated details, not on how a unit feels in real seas. For an electronic helm, the steer-by-wire autopilot guide lists the matching packs. Keeping a lookout is a general duty of the boat operator; the U.S. Coast Guard Boating Safety division provides courses and resources for recreational boaters.

What to pick for your situation

Questions

What does friction mean in a steering system?

Friction is the resistance you feel when you turn the wheel or push the tiller. A well-maintained system moves smoothly from lock to lock. Very heavy or sticky steering is a sign of extra resistance that a drive unit has to overcome.

What is backlash in the helm?

Backlash is the slack you feel before the rudder moves when you turn the wheel. If you turn the wheel a little and nothing happens, the cables, chain or linkage are taking up the movement instead of the rudder. A drive unit has to take up that slack first.

Why does the hydraulic cylinder matter for an autopilot?

On a boat with hydraulic steering, the autopilot drive is often a pump that moves fluid to the steering cylinder. If the cylinder leaks, the fluid is low or air is in the system, the drive cannot move the rudder through a firm connection.

Should I install an autopilot if my steering is worn?

Worn steering is a question for a qualified installer or an authorized dealer. The maker's manual covers installation and setup, and this site gives no installation instructions. Ask an installer to inspect the steering before you commit to a pack.

Can a listing tell me if my steering is healthy?

No. A listing states what is in the box, such as the drive type and the control head. It does not describe the condition of the boat's steering. That is something to check at the helm and ask a dealer or installer about.

What if I am not sure which steering system my boat has?

Check the boat's manual or ask an authorized dealer. Raymarine's drive unit page points boat owners to an authorized dealer when they are not sure what type of steering is installed on the vessel.