I never thought I needed an autopilot until I had one.

If you've never captained a boat equipped with an autopilot, you simply don't know what you're missing. The benefits are huge: no more manipulating the wheel for hours at a time; straight line steering saves time and fuel; distractions don't lead to wandering course lines; trollers can fish and steer at the same time; your hands are freed for additional tasks; and back problems arising from hunching over the wheel or being stuck in the same sitting position for hours are history.

Of course, there are plusses and minuses to everything on a boat. You still have to maintain a watch at the wheel. There will be times, like transiting heavy traffic lanes, when an autopilot isn't useful at all. And yes, an autopilot can get you into trouble if you fail to use it properly.

Yet many boaters consider an autopilot as essential piece of safety equipment, like having a full-time crewmember who does nothing but steer"”and is very, very good at it (and never ever complains). The technology has also matured so that many units are now rich with features and priced more reasonably.

FURUNOMatching autopilot systems with the existing electronics on your boat is a good move. Though an autopilot will no doubt making cruising more enjoyable, there is one big problem: figuring out which automaton belongs on your boat is a serious challenge. But as you will see, a little methodology goes a long way.

THE SYSTEM

Before we can choose an autopilot, we need to make sure we understand exactly what's involved in adding one of these systems to an average boat.

The vast majority of autopilots consist of several different units working in conjunction. The first part of the system is the muscle power, the drive unit. The brawn needs a brain to control it and this is achieved courtesy the second component of the system, the control head. In some cases, the control head will be a single unit and in others it will be split between a black-box unit that mounts out of sight and a dash-mounted control panel. The third main component of the system is the electronic eyes. The brain can't tell the brawn what to do unless it knows where you are going, and that's what the heading or compass sensor, rate compass and rate gyros do.

Naturally, there are some other pieces and parts to the system. Many require a rudder feedback sensor, which tells the brain where the rudder or drive unit is at any given time. Some network with your GPS (most are NMEA 0183 or NMEA 2000 compliant, in these cases). Some also have optional wireless remotes, so you can steer from anywhere on the boat.

THE BRAWN

When choosing which unit to install on your boat, make the judgment based on the size of the drive unit. Once you have the meat of the package nailed down, you can work on matching the brains, and eyes.

In the case of a relatively small sailboat, your unit's muscle can be as simple as a "linear arm," which pushes and pulls a tiller from side to side. Be careful, though. Most of these units are rated for light craft up to 10,000 or 15,000 pounds. They aren't designed for heavy-duty use. Plus, their on-deck location means they are often subjected to salt spray and weather. As a result, they can be more prone to failure over the long haul, especially when used on boats in the upper range of their weight limit, than hydraulic or mechanical rotary drives.

If you have a boat with hydraulic steering, you're in luck, because choosing the proper drive unit is as simple as matching the pump size to the size of the steering arm cylinder. The cubic inch displacement of the cylinder is the key factor, and the autopilot manufacturers will list each unit's capabilities to match it. This can make a fairly significant difference in the cost of your system.

For example, let's look at an inboard boat with a hydraulic steering system that displaces 16 cubic inches. Now say you want to add a Simrad AP24. Two versions are available, one for hydraulic steering systems that displace up to 11 cubic inches and another for units that displace up to 22 cubic inches. You'll have to opt for the beefier version, which includes the RPU 160 drive unit and the AC42 computer. The price difference? More than $500.

GARMINGarmin's GHP-10 autopilot.

If your boat has a mechanical steering system it may be a bit tougher to figure out exactly how much muscle you need. A lot of autopilots simply aren't made with mechanical options. Those that are commonly come in size ratings according to the boat's displacement. Raymarine's Smartpilot kits, for example, go up in 10,000-pound displacement increments. As long as your vessel fits the parameters it will work fine, but make sure you consider your boat's fully-loaded wet weight, with full fuel and water tanks, gear and people aboard. If you're not 100 percent sure a drive unit will make the grade, go for a larger one. If it's close, say the autopilot is rated to handle a boat with up to 20,000 pounds of displacement, and your boat is 19,000 fully loaded, you'd be well advised to go for the larger unit. In fact, if you're even considering upgrading the unit, do so. You won't likely regret it.

THE BRAIN

Once you know what type of drive unit you need, picking out its brain will be a lot simpler"”in many cases, you can simply choose the package that fits. When purchasing that Smartpilot, for example, if you narrow your needs down to a 14 cubic inch displacement hydraulic ram, then the Smartpilot kit that matches comes with Raymarine's X-30 Core Pack (a course computer designed to work with the ram, which includes a fluxgate compass sensor and a rotary rudder transducer). Using a kit like this kills two birds with one stone, because it includes the fluxgate compass your system needs for its "eyes." Since this is a below-deck brain, however, you'll need a separate control display for the dash. Again, Raymarine makes it an easy choice by including one in the kit. Which you choose will affect the kit's pricing, but all of the ST series controllers include plenty of features to get you steering without your hands.

Some manufacturers, like Garmin, take the individual-parts approach as well as the package deal. Go with their GHP-10 and you can choose between a range of different systems and/or kits. It won't be terribly difficult to choose, however, because a PDF on Garmin's web site details what you need to accommodate different engines and steering systems, allowing you to create a highly customized system. With an NMEA 0183 interface you can even design it to do complex functions like tying into the chartplotter's nav and overlay screens. Another note about that Garmin system"”don't think that small boats can't enjoy the big advantages of autopilots. Their TR1-Gold is designed for outboards from six to 20-hp, and comes with a handheld remote control.

SIMRADDash-mounted control heads, like the Simrad's AP28, offer simple operation.Though your judgment should first be based on the size of your hydraulic system's cubic inch displacement, or the boat's displacement for mechanical systems, there are other factors to consider.

Although the majority of the autopilots out there do stand alone – Furuno, Si-Tex, Northstar and others all make units – matching your current electronics system is always a good move. That will allow you to interface the systems more easily, gaining advantages like navigating via GPS to go to waypoints, MOB marks or along multi-leg routes.

You should also look for a control head that is easy and convenient to use. Furuno's Navpilot 520, for example, is a corded control head that has a 3.3-inch x 3.3-inch LCD display, allowing you to kick back in the helm seat and steer with your fingertips. Wireless controls, operated by Simrad, Raymarine and Garmin, are also incredibly convenient, as an add on. For small boat owners, however, wireless won't offer much advantage, yet it will add complexity to the system. If you have a single station helm and an easy-to-reach dash, consider a simple display and control; you'll save both money and installation time.

THE EYES

Once you know the strength and intelligence requirements of your system and have picked out a control system, you may want to consider upgrading your system's eyes.

One of the least understood and most under-appreciated parts of your autopilot is its heading sensor. Most of the kits on the market include functional, but relatively low-grade, heading sensors. Upgrade yours to a digital fluxgate heading sensor like KVH's Autocomp 1000, and your system will be able to automatically compensate for heel and rolling. It also allows for complex features like automatic heading compensation to GPS chartplotters, radar and computers, so long as they're NMEA 0183 compatible.

Another choice would be Maretron's solid-state electronic rate gyro compass, the SSC200, which is both NMEA 0183 and NMEA 2000 compliant. This unit claims better than one-degree accuracy even during 45-degrees of roll or pitch, and it updates heading info 10 times per second.

Upgrades in the system's heading sensor are worth considering because an autopilot has a hard time dealing with the same problems that confront you and I when we are at the wheel. Big seas shove us off course. A strong heel, set and drift, crosswind, or increased rudder deflection caused by these problems, all add up to less stable course lines. In some cases the effect can be even more dramatic than it is when a person is on the helm, because an autopilot can't look through the windshield, see waves coming and prepare to counter-steer.

But high-quality heading sensors can account for some of these issues and will make your autopilot more accurate. In many cases, installing a high-end sensor like those mentioned above can make the difference between S-curves and zig-zags, or a straight line.

RAYMARINEThe latest in autopilot controls, like the S100 from Raymarine, can be rigged for wireless operation.Another upgrade worth considering is going to a unit with virtual rudder feedback, eliminating the need for a separate rudder feedback sensor. Though the ultimate function is the same, fewer parts mean less chance of failure at any give time, plus a less-complex installation.

Display type is another upgrade opportunity. Color displays, a relatively new development in autopilots, are now available from Northstar (the 3300, which goes for about $700) and Raymarine (the ST70, which goes for a hair under $1,000). But the primary upgrade most folks will want to consider is simply going bigger. Larger display units mean you can easily read the larger digits from father away – a nice feature if you have to leave the helm.

COMPLEX FUNCTION

Though the autopilot manufacturers won't want to admit it, the truth of the matter is that most of the autopilots out there have most of the functions you may ever want or need. The exception are tiller pilots. These tend to be a bit simpler in the brain department. Autopilots made for powerboats, however, are expected to handle a wider range of more complex functions.

Those used by anglers, for example, often have a way for trollers to go in a pattern other than a straight line, without losing sight of their overall course. Raymarine's Smartpilot addresses this need with a programmable fishing pattern function. Simrad's AP units feature depth contour tracking features, and zig-zag patterns. Furuno's NavPilot and Garmin's TR-1 both have cloverleaf, orbiting, and spiraling patterns to assist you in your search for fish.

The bottom line? All of these manufacturers are making autopilots that include most of the features you'll ever want to use, plus a lot that you wouldn't even think about. So don't make a feature-driven choice. Instead, once you determine which manufacturers make a unit that has the brains and brawn to appropriately steer your boat, look to usability, ease of installation, and the ability to interface with electronics you already have onboard. These are the factors that should best help you in making your decisions when you go autopilot shopping. Choose the right unit and have it properly installed, and one thing's for sure: you'll feel like it's your best friend – except that it never complains.

Lenny Rudow was senior technical editor for Boating magazine for more than 10 years, and is currently the electronics editor for Marlin and GoBoating magazines.