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Autopilot
- The principle reason for poor records of autopilots is that many of the cheaper models – particularly the cockpit autopilots – are not built for serious, sustained use. As the wind and waves build, the loads on an autopilot can increase exponentially. A unit that is perfectly adequate for light weekend use gets overwhelmed. Not only will the autopilot be unable to steer the boat properly, but it also will be continuously stressed to its limits, resulting in mechanical and electrical failures (destroyed linkages and gears, burned-out motors, and failed electronics components through over heating – all are common). (Cruising Handbook, p. 85)
- At the core of the drive end of most autopilots is a small electric motor. To get the kind of force needed to steer a boat, it is geared down. The more it is geared down, the greater the force it will develop, but the slower its response time will be. From the point of view of steering a boat the problem is that as conditions worsen, steering loads increase – requiring a powerful autopilot – just when response time needs to decrease if a steady course is to be maintained. (Cruising Handbook, p. 86)
- The only way to be sure of accurate helming from the autopilot in all sea states and conditions is to have a large, powerful, fast, and expensive system. If it cope with the rough times, it will also handle the smooth without a murmur. Ideally, the unit will incorporate a rate sensor or gyro plus compass that can identify motion that results from wave action (especially in conditions with large, following seas) and does not overcompensate. If going offshore, the bottom line is to buy a unit big enough for bad weather. Otherwise, the crew ends up hand steering the boat at precisely the time they would rather not steer at all – in fact, they may end up steering all the time if the autopilot fails altogether. (Cruising Handbook, p. 86)
- When installing an autopilot, it is important to ensure that the electrical cables are adequately sized. Under load, many below-decks autopilots draw 20 amps or more (tiller or wheel-mounted pilots use much less energy, but with a commiserate reduction in power). Inadequate cabling results in voltage drop, loss of power, overheating, and motor burnout….Both the electronics and the drive motor need to be in a cool, dry location with a reasonable air flow. (Cruising Handbook, p. 86)
- Autopilots consume from 50 – 150 amp-hours a day at 12 volts. At sea, this is likely to be the biggest load on a DC system….[with all systems including radio radar and SSB it could be 300 amp hours]…the load may be double what it is at anchor….This energy crunch, as much as anything else, makes a wind vane such an attractive proposition for offshore cruising – not to mention that if both an autopilot and a wind vane are fitted, the boat now has redundancy in case one fails (in practice, it will almost certainly be the autopilot). (Cruising Handbook, p. 86 – 7)
Wind Vanes
- There is no question that the servo-pendulum type is the most effective – I would not consider any other type for offshore work…Servo-pendulum wind vanes develop a tremendous amount of power when a boat is moving at speed and, as a result, require a very sturdy mounting bracket. (Cruising Handbook, p. 84)
- From a safety perspective, it is essential that all course adjustments can be made from within the security of the cockpit rather than having to hang over the stern. (Cruising Handbook, p. 85)
- A wind vane must be set up so that it can be disconnected almost instantly if it becomes necessary to recover control of the wheel or tiller. (Cruising Handbook, p. 85)
- It is also important to be able to get the oar out of the water when not in use. The oar itself needs a weak link so that if it fouls something at speed, it will fold or break away rather than rip the entire unit off the back off the boat. (Cruising Handbook, p. 84)
- A wind vane needs to be able to control the boat in relatively light apparent winds; otherwise, it is not going to be useful much of the time when going downwind. If the boat will not balance, or has poor directional stability and wants to scoot all over the place, even the best of wind vanes will not do well. (Cruising Handbook)
- A narrow boat or one with a relatively long keel generally performs better with a wind vane than fin keeler. As the wind pipes up and the steering loads increase, the wind vane needs the power to keep going. It should not be necessary to reef down prematurely just to east the load on the vane, which means the vane must be powerful enough for the job and the boat must be well enough balanced not to overwhelm it. (Cruising Handbook, p. 84)
- To be most effective, wind vanes should be installed on the centerline… (Cruising Handbook, p. 85)
- Given the relatively high cost of a wind and the fact that they are not appropriate for inshore work (if the wind shifts, you may find yourself on the beach)…For offshore passages, the primary justification for using a wind vane is that it uses no power, as opposed to the typical autopilot that consumes a considerable amount of power. Furthermore, wind vanes have a fairly good reliability record, which many autopilots do not. The farther it is intended to travel offshore, the better a wind vane looks. (Cruising Handbook, p. 85)
- If sailing alone…it is very important to have some means, such as a tripline, of disengaging the autopilot or vane so that the boat will round up, slow down, and permit the man overboard to gain the deck. An easy means of climbing aboard is also essential. (Upgrading the Cruising Sailboat, p. 159)
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