Subject: Re: HP Autopilot
From: Mike Crawford
Date: 12/7/2018, 3:47 PM
To: harryproa@yahoogroups.com.au

Realink,

  Ahh, the ST200.  I can see why you're skeptical.  I wouldn't use a self-contained tillerpilot for anything other than convenience when daysailing in good weather.

  My apologies -- I can see where the word tillerpilot was confusing.

  I was referring to the ST4000, (later the S1, and now the EV-100), with all the electronics inside the boat, hooked into a SeaTalk or NMEA network, and a separate compass/sensor that you mount  on the inside of the hull.  The linear drive is the only thing that's outside the boat. 

  The mechanical part does make a bit of noise, but it never bothered me except for when the water was choppy and I had the sensitivity set too high; I couldn't believe how frequently it was adjusting course.

  Were I to go mechanical, I'd consider your suggestion of putting the drive inside the hull, so that only the stainless arm protrudes through a small slot.  That wouldn't work on my current boat, where the tiller needs too much range of motion, but it shouldn't be a problem with a shorter tiller right on the rudder stock.

  Then I'd later do the math on what type of drive to get.  Maybe it makes sense to get a handful of ST-4000 type drives at a lower cost, or maybe the failure rate is so much lower on the EV-200 linear drives (either mechanical or hydraulic) that my six-pack idea ends up being silly.

        - Mike



realink@iprimus.com.au [harryproa] wrote on 12/7/2018 3:27 PM:
 
bang for buck, hmmm

2 linear drives, a wrecked tiller pilot
this should cost a bit less and the ST1000 and ST2000 which offer 120lbs and 170lbs thrust respectively. The waterproofing just isnt there, nor is the build quality, but thats ok you can keep the electronics and use linear drives of decent quality. Your electronics inside the ST incorporate a single fluxgate compass as standard and the wiring to go to a master controller.

ok so to travel in one direction you set the tiller for heading hold, and the forward rudder is parked. Thats just simple direction mode travel which returns the forward rudder to park. When you shunt you manage that manually, shift direction mode which parks the new forward rudder and makes the latter the tiller. You can reverse the polarity of a linear drive when you shunt the other way and flipped direction control, so you have effectively flipped control with the same mechanism.

The fluxgate wont matter because you just have heading hold when you engage it. I dont think the boat will have any sense of which end is the bow. Once you get moving line up to your next way point from where you are and you can auto helm off the chartplotter.

If you could keep 2 rudders shipped all the time you have a normal rudder and a canard rudder.. You have to make them anyway just not lift them saving an operation. The rudders can be ogival forms so they lift against leeway, then they do something worthy other than just produce drag.

Back to linear drives, I think thats how theyre wired in ST4000 wheel steer, so that the wheel will turn each way they just switch polarity, but my god the noise it makes, it sounds like a food blender with a bucket of bolts.