I have an ST4000+ wheelpilot on my 33ft Dick Carter sail boat. IMHO it is an essential piece of safety equipment when you are sailing shorthanded, or even just with a smaller crew (i.e. less than 4 people).
I recently had a challenging night offshore after splitting the mainsail in a squall (just after putting the 3rd reef in). Even though I had two crew, they were both too sea-sick to be of much use, and the autopilot steered perfectly under motor while I lashed the main to the boom and set the storm tri-sail.
The benefits in freeing you from the “Tyrrany of the Tiller” is obvious.
It is vitally important though that you:
fit a rudder angle sensor, otherwise the Autohelm performance will be mediocre at best, but probably next to useless;
select the location for the fluxgate compass very carefully to avoid magnetic and RF interference.
- Getting it as close as posible to the keel will also minimise unecessary movement of the fluxgate, making the Autohelm more stable;
make sure all wiring is done professionally, cable joins are avoided as far as possible and cables are routed in dry areas (keep them out of the bilge if possible).
The Autohelm on Sunny Spells was pretty useless when I bought her, but after fixing the problems listed above, she now helms perfectly downwind for hours on end. I’ve had an 11 hour run downwind with poled out genoa and main by the lee without touching the autopilot controls (on wind-vane mode) other than accepting wind shift alarms.
The best $1000 you can spend!