Why do auto-pilots fail on long trips??

[evm1024]

Originally Posted by funjohnson

You're online. CPT plus an additional search phrase like "boat, autopilot, yacht, sail) brings it right up in Google. Unless they called themselves The High Powered Wheel Autopilot Company, how is a brand name different than initials?

Matt

Google search 101....

Add context for improved search results.

[daletournier]

Originally Posted by billknny

You left out one other positive aspect of a mechanical windvane... they are fascinating to watch work! Or maybe that is just my engineer heart...

This is true, but not sure why. I've just stared at mine many times, there's some sort of natural thing happening.

[evm1024]

I'm still a couple of years from full time cruising.


Currently I'm using a Raymarine SPX-30.

When I bought the boat it came with a non functional Navico pilot with a rather robust RAM and Navico branded Octopus pump. So rather than had steer to get it home I bought a Ray SPX-5 wheel pilot. The SPX-5 did fine for the trip down the coast.

I still have not rebuilt the pump yet and just use the SPX-30 to drive the SPX-5 wheel.

The SPX-5 can drive a pump and between the SPX-30, pump on one hand and the SPX-5, wheel on the other hand I have a full spare.

I do have schematics for the AP. I might buy a few spare MOSFETs....

I do look at the CPT pilot as an optional spare.

[DumnMad]

Originally Posted by UNCIVILIZED

There's what's been mentioned:
- oversize everything; wiring, motor, parts, etc.
- balance the boat via proper sail trim, & moving onboard "ballast" (heavy items) around

Also, build redundancy into your self steering. Such as a 2nd AP of the same make & model. Either operating in sleep mode along with the one which is driving the boat. Or to have as a spare for when the #1 pilot fails. And have spare parts onboard to repair the failed unit while the other one is driving.

All good points but the 'lots of spare parts redundancy' sounds a bit like planning for failure rather than planning for success.
Our redundancy took the form of a long punishing period of hand steering and a few lessons learnt.

My view is that if I had understood my equipment better, I would have monitored the batteries better and if I had done that there wouldn't have been an overstressed electric pump motor and nearly 2 weeks hand steering.

I'm picking most boats sailing offshore NZ have the correctly sized auto-pilots. But heavy weather sucks the power out of the batteries and far too many transitting crews are having AP failure.
I now understand AP's are not designed to run in big waves when powered by semi-flat batteries.

[Exile]

Originally Posted by Jim Cate

Not quite correct. Add AutoHelm (sold by Scanmar) and Windpilot... both sell auxiliary rudder vane models, and both have many successful installations on center cockpit boats. Or you can do as I did on our previous boat and build one yourself, saving a couple of kilobucks and learning a lot about wind steering along the way!

Jim

Thanks Jim. I'll take a look at both your suggestions. Good to know there are alternatives. As for building my own, I'm no physicist nor engineer, retired or otherwise!

[Rorzech]

I bet you know this one , KFC .

[daletournier]

Originally Posted by Rorzech

I bet you know this one , KFC .

From a positioning point of view acronyms aren't a good idea, no one knows what they mean, trendy, look cool but stupid. Marketing, branding is about easily getting your product known.
KFC works because they through huge amounts of money at rebranding , and most companies don't have a budget that justifies teaching the world what your letters mean.

[Rorzech]

I Googled NASA and I got "Never A Straight Answer"

[billknny]

Originally Posted by DumnMad

I now understand AP's are not designed to run in big waves when powered by semi-flat batteries.

It might be too obvious to say, but if you don't put as much power INTO the batteries as you take OUT, (plus a bit) eventually EVERYTHING on the boat that runs off the batteries will stop working. Obvious, right?

If you are running an boat that requires electricity, and if you have an electric AP you have a boat that does, at least one person on board needs to TRULY understand how to manage the electrical power generation and usage, otherwise it is only a matter of time before things go tits up.

It's not rocket science, but it's not a no-brainer either.

I have more than a bit of doubt that the most common issue is electric supply. The only part of the AP that would fail because of that is the electric motor. I don't see the drive motor as being the biggest point of failure, but I could be wrong... Transmissions, linkages, simple mechanical things seem the more common issue.

[SteveSadler]

Hi Jim
As mentioned we sailed under Genoa alone at night. DDW monos will roll too much if no main is up. But when we have to we strike the main to make steering easier. This is only half the problem. In huge following seas, and tiny sails up, its the seas that cause the steering problems not the wind.

[quike]

why not buy a nice windvane autopilot

[Neptune's Gear]

IMO all these problems are created before leaving Port, with the exception of trim/balance. If the boat is hard to steer manually, it will eat electricity, and wear its components. To say that APs can't steer in heavy conditions for long period's, including rtw, is just incorrect. My B&g unit has around 40,000 miles on it, including 4 passages leaving and returning to New Zealand. It has had one new set of motor brushes, one new set of hydraulic seals, and I upgraded the computer unit early on to a better one. No issues since.
So my advice is spec it well, learn how to balance the boat properly and you'll have good service. Same for the electrical system, so you don't run out of power.
Oh, one other trick is to tie a Turks head on the top of the wheel at the straight ahead position, then by simply looking at where the knot is around the wheel, you know how much rudder is being used by the ap to go straight. More than around 6 degrees of rudder means better balance is required.
Rember that boats like Hugo Boss single hand around the world on an electric AP. In that case it was a B&G H5000.

[Jim Cate]

Originally Posted by SteveSadler

Hi Jim
As mentioned we sailed under Genoa alone at night. DDW monos will roll too much if no main is up. But when we have to we strike the main to make steering easier. This is only half the problem. In huge following seas, and tiny sails up, its the seas that cause the steering problems not the wind.

I must have misunderstood your post. Sounded like you just rolled up the genoa and left the main alone.

At any rate, we've found the boat to have better directional stability with just a headsail when sailing deep angles in heavy wx. Your boat may be different.
We've also used a deeply reefed main sheeted amidships to limit rolling (more on our previous boat, when running two headsails in the trades.

Finally, if the boat is defeating the a/p even with the proposed sail plan, towing a drogue will help keep her straight. Not a real "stopper" drogue like a JSD, but something to limit surfing and keep max speeds down to say 6 knots or so.

Jim

[DeepFrz]

I remember one Nordhavn owner talking about why he chose Nordhavn. One of the items he pointed out was that some of the competitive boats had auto pilot actuators the size of his little finger. Sure, an exaggeration, but I bet most production boats have undersized auto pilot actuators and drive computers. Spec'd right and installed properly an auto pilot should last a very long time.

[a64pilot]

Now, I don’t pretend to be a sailor as I am very inexperienced with sailboats.
However as far as sail trim and rudder fighting it, I just put a zip tie on the wheel spoke that is straight up when the rudder is centered. With just a glance you can tell if the autopilot is having to hold rudder against the sails. Plus with the CPT Autopilot if it starts working too hard the belt will jump on the sprocket and you can hear that.

First two years or so we had no Autopilot, we hand steered everywhere we went. Now we were not full time so in truth that was one two week vacation a year and as many long weekends as we could get etc., but no real passages, longest about four days.
At first I was going to fit a “real” Autopilot, you know a high speed expensive one that learns the boat etc. but not having an Autopilot was turning into a real bear, so I bought a CPT as I wanted one as a back up.
Reasoning is with my solar panels etc, your not fitting a windvane on my boat and I can just imagine losing the AP three days into a two week passage. I wanted an easy to install back up, and a CPT once the deck fitting and wheel sprocket is mounted can be installed with no tools in literally a minute or two.
Anyway after having the CPT for a couple of years, I don’t think I need a “real” Autopilot, it holds a course pretty well, and what else do you really need? Plus it’s silent, no groaning etc down below, and it uses very little power, in truth I don’t know what it’s power consumption is as it doesn’t even show up on my amp meter.
http://cptautopilot.com

Now as to whether it will steer your boat or not, it will deliver 86 ft lbs of torque to the wheel, that means of course if you hold the wheel spoke one foot from center it will apply 86 lbs of force, 43 lbs at two feet of course.
If your wheel is five ft in diameter, it may not steer your boat well, but if you have the average three ft or so wheel, I believe it can easily.