Realink,

  I agree with most of what you write, but have been debating a different approach.  Debating -- I'm not sure if I like my own logic yet.

  The base system would be a Raymarine EV-100, 150, or 200 autopilot:

    https://www.westmarine.com/buy/raymarine--evolution-ev-100-tiller-sail-autopilot--14907745

  I've been using an ST-4000 with the ball-drive linear tiller actuator for ten years now and have grown to like it a lot.  On a daysailer, which obviously is different than a cruiser. 

  It integrates with the rest of the marine electronics, including the wireless TackTick instruments and the chartplotter, so it can sail on a specific course, sail to waypoints laid out on a nmea 2000 chartplotter, and also sail relative to the wind.  Note: sailing to the wind is not as instantaneous as using a wind vane, but it's still quite handy.

  The wireless remote is great, so the electronics and control head can all stay inside the boat (or at least under cover and slightly out-of-the-way).  It also has different levels of sensitivity, so you can give it several seconds to correct course in steady wind and calm seas, using less power, and then adjust it to very quick course corrections in gusty wind, chop, or steep/short following seas; the fastest setting is even quicker than sailing by hand, catching really minute course changes that I wouldn't try to react to (I've only used the fastest setting for testing).

  The actuator has no controls on it, just a waterproof cable that connects to a waterproof plug, and I remove it to store it inside the boat when on the mooring.  It's mechanical, and will eventually wear out, but since the part is as low as $350 if you shop carefully, you could get a six-pack for $2,000.

  Then, either:

    a) Two autopilots, one for each tiller, with the other one dormant when heading "backwards".  A $1,800 cost penalty, but it also provides built-in online redundancy if one of the pilots fails.  Since you generally wouldn't use an autopilot when short-tacking, using one or the other probably would not be too bothersome.

    b)  A single autopilot, but two directional sensors, one for each direction, with a toggle switch to flip between the two.

  I'd probably beef up the exterior waterproof plug with a secondary waterproof cover designed as an added precaution.

  ---

  The first argument against it is that it costs too much.  The second is that the actuators will fail before hydraulic ones.
  
  However...

    - So much money is being saved by going with the HP in the first place that the few thousand dollars extra still yields a total far below an equivalent trimaran.

    - It's really simple and redundant.  If the actuator goes, swap it out.  With six on board, you can go through a lot of failures and still be auto-piloting. 

    - No hydraulics, hoses, fluid, fittings, or spare parts to repair and/or keep track of.

    - Just one wire cable leading to the actuator.

    - It's nice to be able to adjust sensitivity, sail by waypoints, sail by the wind, and use the remote.  It's quite handy to dodge boat traffic and lobster buoys on the way  back home while putting sails away, or hang out on the bow tramps while motoring and still be able to steer. 

    - You can always switch up to a below-decks mechanical or hydraulic linear drive, or hydraulic steering, if the redundant-mechanical-actuators theory doesn't pan out.

 
  With an outboard for power and the wired/mechanical tiller actuator, there's almost nothing belowdecks to fail, leak, catch fire, or repair.

  Sadly, I'm not sure a spare outboard in mothballs makes sense weight-wise.  But the outboard is still pretty handy in terms of getting the motor serviced.

  Perhaps a 20 hp ultra-long-shaft motor, at around 120 lbs, wouldn't be too much extra weight to carry.


        - Mike

 

Just keep in mind Im clueless and have no idea what Im talking about

Having said that, 'if' this machine was electric ...

Ive never quite appreciated how expensive AP is, and if you look at Raymarine stuff its really bonkers cheap built with the cheapest of parts and fails regularly. The tiller pilots are a bunch of plastic gear wheels and rubber belts, a 'very' cheap motor that wouldnt exceed 20 watts which is like $5 on todays technology and a simple inbuilt fluxgate compass, which it probably doesnt need. Dont get me started on their wheel steer AP.

Looking around the business I used to have a throw away line about helicopter technology being somewhat underdone, as at the time you could buy a model helicopter with features like heading hold and altitude hold that would make a chopper pilots life much simpler that full sized helos costing millions didnt have. In the interim decades however newer design helos have incorporated these features.

Back to the toys, they have a simple gyro costing in the order of $70 - $250 that allows a trim which you can set first statically then control via radio. Its job is to position the fuselage direction in such a way that when deviated from path the circuitry activates a servo which re-establishes the heading. Its called simply heading hold. Rather like tiller steer, you establish a heading and press a button for the equipments linear drive to hold you on course automatically. Push the model off course and heading hold will bring it back unfailingly.

Now Im aware the marine product can do other things like work with a chart plotter to eliminate leeway, but Ive always felt like the former course keeping is all I really need. I just find it curious that a few hundred bucks in parts and a linear drive becomes $4 grand.

Having made you read all this nonsense  and deviated somewhat from the question at hand I should just mention that the aforementioned model is an electric machine, and you use the same equipment to steer the thing with or without the gyro 'on'. Just an idea but if the energy consumed by 30 watts of current could easily be replaced wouldnt linear drives make things just a tad simpler, and more useful to have a form of autopilot to boot.

Well just a thought, .... as you were ...

cheers to all BTW ..