Autopilot from scratch

[Jim Cate]

Sorry, when I wrote my earlier post I hadn't noticed the worm drive. That does in fact mean that you can't fit the typical tiller arm drive to the rudder, no matter what type of ram or drag link you use. Rather, some means of driving the sprocket where the wheel/chain interface are seems practical.

Jim

[olaf hart]

Originally Posted by lockie

That's right: Raymarine ST1000/2000 tiller pilots have no end-of-stroke protection and will grind themselves to eventual death when the tiller ends up hard-over. The Simrads have built-in stall detection and hence are protected from this.

So you must pay strict attention to sail balance. Of course if you are in heavy conditions, the helm will end up hard-over repeatedly no matter what.

This is why after repeated failures and warranty fixes, I fitted limit switches to my ST2000, which now works beautifully and I believe its life-span will far exceed a new one.
Apologies to OP, now back to your topic....

Cheers, Graeme

IIRC the old Simrad TP 2200 and 3200 had limit switches as standard.

I used a bit of line that limited tiller arc when using a Raymarine TP, I also had a 2000 unscrew itself.

Not sure if it helped, or it was the loctite I used to screw it back in place..

Anyway, limit switches are the way to go.

[daletournier]

Originally Posted by gmakhs

After sailing for the last few years , I can only tell you the only thinks electric autopilots do well is failing when you need them or randomly and consuming a lot of power .

Your idea of hydraulic is good and I believe the best option if you decide to use electric auto pilot .
Now from the other hand , you can manufacture a steel or fiberglass auxiliary transorm hugging rudder with a trim tab that can work with windvane or small tiller pilot , that way you will have 2 rudders in case of emergency and improved manaurabilty.

The other option is a servo pedalum wind vane .

In general wind vanes are more reliable and easier to repair than electric auto pilot .

3 auto pilots have failed me in the last 2 years , all of them the where over sized for my boat .

Ps : I don't know if it's only me but windvane creates a smoother motion on bad weather as well .

I have had my autopilot fail three times this year. First the pin that connects the ram sheered, then the belt, then the brushes.

My Hydrovane never failed.

[olaf hart]

Originally Posted by Jim Cate

Sorry, when I wrote my earlier post I hadn't noticed the worm drive. That does in fact mean that you can't fit the typical tiller arm drive to the rudder, no matter what type of ram or drag link you use. Rather, some means of driving the sprocket where the wheel/chain interface are seems practical.

Jim

Surely you could still use a dedicated tiller arm on the rudder shaft, I thought is was not recommended practice to attach a linear drive to a steering quadrant..

[olaf hart]

Originally Posted by daletournier

I have had my autopilot fail three times this year. First the pin that connects the ram sheered, then the belt, then the brushes.

My Hydrovane never failed.

A lot of the newer fat boats are a handful to steer in a following sea

Was that your problem?

[Bruce K]

Originally Posted by olaf hart

Surely you could still use a dedicated tiller arm on the rudder shaft, I thought is was not recommended practice to attach a linear drive to a steering quadrant..

A worm drive allows drive from one direction only, ie wheel can drive tiller, tiller cannot drive wheel. Look it up online.

[Bruce K]

Maybe you cpuld drive the worm with a reversing electric motor type autopilot drive, this could be very strong, depends on access, perhaps a double chain sproket?

[olaf hart]

Originally Posted by Bruce K

A worm drive allows drive from one direction only, ie wheel can drive tiller, tiller cannot drive wheel. Look it up online.

Thanks, sounds like the simplest solution is a CPT wheel pilot.

[thomm225]

Originally Posted by lockie

Well blow me down, I must have dreamt the time the belt stripped and I had to helm solo for 9 hours, and the time the motor burnt out, and the three times the drive rod unscrewed and fell out due to stall torque, right? You were there on my boat and I wasn't, and I just made this stuff up right? And I made it all up so I could spend hours designing and fitting the limit switches?

You can disagree with my opinions, but don't imply I am a liar when I simply report my own factual experiences.

Do a bit of googling on ST1000/2000 problems and you will see such failures are far from uncommon.

I'm going by how mine reacts. It vibrates a bit when at the end of it's range then stops.

I don't go by so called reports online about how it works. You can always find anything you want online in a positive or negative way on just about anything these days. Plus you don't know how the owner treated their autopilot

If you want to make a big deal about it, that's entirely up to you.

I like the Raymarine ST2000 because it's quite and easy to recalibrate when I change tacks whereas the Simrad TP10 is a pita to recalibrate

[daletournier]

Originally Posted by olaf hart

A lot of the newer fat boats are a handful to steer in a following sea

Was that your problem?

The pin was a fatigue thing compounded by it working hard due to several days of heavyish weather, not uncommon, Google it.

The belt was a separate incident and to be honest I'd been working the autopilot hard using a code zero in gusty weather.

The commuter needed a light sanding, dirty from years of use, brushes were half worn so I replaced at the time, once again fairly common.

[Lepke]

One issue with hydraulic steering, the wheel position changes. You probably have amidships position marked on the wheel and because it's mechanically locked to the tiller the position stays the same. But with hyd steering there's always some wheel slip, so you need a rudder angle indicator.

[Rob Toronto]

I get where you're coming from, but I'm not sure what is actually practical. I don't have a conventional steering quadrant, so a linear drive is not an option, (nor most windvane types of steering as far as I know) The shaft of the rudder attaches to a 26" long tiller arm which is driven by a worm gear from the wheel (via chain). There is no option in the current configuration to drive the tiller arm without disengaging it from the wormgear. The only option I can see is your second Raymarine option of a rotary drive motor to the chain. There may be a heavier duty unit out there, but the ones I've seen are limited to a boat 24000 lbs or less. My boat fully laden for cruising will likely be upwards of 36000 lbs!

[Rob Toronto]

Doing a bit of research, and with the advice of you guys (thanks) I'd like to explore the rotary drive option, but all I can find is units for boats up to 40' and 24000 lbs. Mine is a big a** 43', 36000 lbs. steel ketch with a full keel. When hand steering hard over at over 5+ knots, she takes quite a bit arm strength to get her to come about, so I'm very concerned about any autopilot being under-powered.
If anyone can point me in the direction of units that are suited to my requirements, it would be much appreciated.

[Rob Toronto]

Also, when looking up rotary drives the power produced is stated in kg/m. Any ideas how to calculate what is required?

[gmakhs]

Why not auxiliary rudder with trimtab windvane ??? Seriously , you can even add an tiller pilot to it and it will.steer your boat doesn't matter the weight of it .