Mailport: June 2014
Autopilots and Cruising
Some comments to your article on autopilots in the April 2014 issue: Hands down, for offshore cruising, the electric autopilot is the most repair prone and most expensive gear to replace, in my opinion. (See the equipment surveys of the Seven Seas Cruising Association, www.ssca.org.) Over many tens of thousands of offshore miles, we’ve found the pilots to be the most expensive gear to replace; offshore sailors routinely carry a complete backup. Figure on 500 hours between failures. Typically, it’s the computer module that fails on conventional units since the power to run the hydraulic ram is typically routed through that module. For coastal sailing, autopilots can last decades, provided all the components are kept scrupulously dry. On a calm day, the smallest pilot can navigate a 100-footer, but when offshore, even the largest pilot available to recreational users will be unable to exert sufficient control in heavy quartering seas. All the more reason to never leave the pilot unattended during running or reaching in a good sea, lest the boat quickly broach.
It’s a good idea to buy the largest electric hydraulic ram drive available. Raymarine drives are built in the UK, and its largest drive, a Type 3—even though rated to about 70,000-pounds displacement—has difficulties once past 50,000 pounds. Most manufacturers use the same reversible motor, so they’re often switchable among brands. The motors are fairly small, so they’re sensitive to heat buildup, and usually not water-resistant. Replacing the motors is usually not difficult, provided you have an ample supply of hydraulic fluid to bleed the system. The solenoid switches built into each ram occasionally fail and are not so easy to replace, unless you’ve seen it done before.
Offshore sailors usually learn the hard way that effective use of autopilots requires ongoing attention to sail trim. The objective is always to minimize the rudder load on the pilot.
When installing a new or replacement autopilot, it’s a good time to also replace both the steering cables and the chain. When a steering cable or chain fails offshore, even the most capable mechanic is bound to say “uncle.” Some coastal sailors never change their steering cables/chain, but actively used boats are usually advised to do so every three to five years.
Peter I. Berman
“Outfitting the Offshore