This article walks you through our extensive collection, asking questions and making recommendations along the way.
What Autopilots Do Best
Autopilots do a great job of maintaining a consistent course in light to moderate conditions with minimal rudder movements. They don't tire out like their human counterparts and have an infinite attention span. They will open up opportunities for you to use your boat that you might miss due to crew shortages and because they steer so precisely, they will save fuel and get you to your destination faster, especially when linked to GPS.
How do Autopilots Work?
All autopilots have three main components: a direction sensor that is usually a flow compass, a central processing unit (cycle computer) that is the "brain" of the autopilot, and a drive unit, which is a hydraulic motor or pump that applies force to the autopilot. Rudder your boat. More complex pilots connect to additional sensors: data sources that may include a wind vane; A rudder reference that tells the pilot's handler where to point the rudder; A modified gyro that tracks instantaneous pitch and yaw movements and a GPS receiver or speedometer. It's the driving mechanisms, matched to your boat's steering type, that explain how autopilots differ from one another. We will talk about how to choose the right one later.
When Autopilots have Trouble Steering
Here's a rule of thumb: If you're having difficulty holding a course, your autopilot will too. Unlike a wind vane (a mechanical, self-steering mechanism mounted at the stern of a ship and used on cruising sailboats), autopilots for marines work harder as seas get heavier and winds get stronger. Eventually, the pilot's power limits are reached, and the device breaks down.
According to cruise expert and naval engineer Steve Dashed, a properly sized autopilot uses 10 percent of its power (or less) about 75 percent of the time, and all of its power less than one percent of the time. If you use your boat on a calm lake, this won't matter. If you're a Bluewater, that percentage of the time might be when you really want your pilot working with you, in bad weather when the conditions in the cockpit are the worst for you and your crew.
When the Autopilot Fails in the Cockpit
Over the years we have learned a lot about what works and why things fail. By sharing this information with you, we hope that you can avoid the inconvenience that an autopilot failure may cause. Perhaps the biggest problem with autopilot reliability is that long-distance sailors often purchase small cockpit-mounted autopilots and then expect them to work flawlessly over a multi-year cruise.
Therefore, we do not recommend using autopilot in the cockpit for long-distance cruising unless one of the following applies:
- Have a backup autopilot in case your first autopilot fails.
- You have vane steering and don't rely solely on the autopilot.
- She loves to hand guide for long hours.
Take into Account the Boat's Length and Displacement
How do you estimate the limits and correctly size the autopilot? The boat's design, length and displacement are crucial. In general, long, narrow dinghies, boats with V-shaped forward sections, and sailboats with a long catapult are more directionally stable. How easy is it to steer your boat? Suspended rudders of the "barn door" configuration require more force to move than rudders with a lightly steered, balanced spade.
If your boat isn't well balanced, your pilot may have to fight the weather rudder (and you may want to throw a reef into your mainsail or change to a smaller jib to balance your spinnaker rudder, for example). Remember, the tiller-mounted pilot is trying to steer about 18 inches away from the rudder axis. Autopilot is not a solution for a difficult-to-steer boat. The autopilots below deck are much stronger, more reliable, and more effective. They're better at steering, so they should be your first choice for longer trips.
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