Understanding autopilot packages/options

[ylop]

It's worth saying that you can make the pypilot control as simple or complicated as you like -- that's the beauty of it. I've just built one, and the control panel in the cockpit is literally going to be three buttons: engage/disengage, port, and starboard. If I want to do anything more advanced I can access it with my iPad or mobile.

I'm not afraid of doing "stuff" with a pi in general but I have some reservations:
- not being able to disengage could be a safety-critical issue.
- water ingress is always a concern for any DIY electronics - to my mind that could actually mean it could turn itself on which is probably scary
- the "normal" option seems to be a wiper motor, but if I understand the torque correctly would be less than the wheel pilot that people say is only just good enough
- I want the rest of the regular crew (wife/daughter/son) to feel confident using it and they should be able to use the main features without needing to know an IP address or debug why the tablet isn't talking to the pi
- its not that unusual to the pi (or perhaps its OpenCPN) to crash.
- having never really used an autopilot, I'd have no real benchmark for whether I was getting good/bad results

That might be paranoia. I've not seen a really nice documentation of someone using it exactly the way I would envisage so I am imagining spending too much time making it work, which might be fun but until I retire is probably eating into sailing time. If its truely easy to make a robust solution for a fraction of the price of a wheel pilot, there's a market opportunity there for someone to sell a neat package.

 

[ylop]

Only if you don't expect too much from it, have very little play in your wheel to rudder linkage, your steering is featherlight

There's not much slop in the steering. I can sail with one hand (indeed one finger) in most conditions - if its more difficult than that then something is trimmed wrong... I'm not saying we are immune to making those mistakes, but probably more likely to adjust reefs etc if we have an extra "pair of hands".

and you don't sail solo!

Can you elaborate on that? I don't, but I might want to in the future. What's the issue with sailing solo?

 

[GHA]

- its not that unusual to the pi (or perhaps its OpenCPN) to crash.

apologies for slight drift but in case anyone else thinks this happens, if it's openplotter image then crashing is pretty much certain to be a problem on your installation. It should be rock solid. Overheating CPU/inadequate power supply/cheap SD card are by far the most common causes.
Back to the thread....

 

[KompetentKrew]

Can you elaborate on that? I don't, but I might want to in the future. What's the issue with sailing solo?

You just want an autopilot that is 100% reliable.

Madness to buy a cheap autopilot IMO.

 

[Tranona]

There's not much slop in the steering. I can sail with one hand (indeed one finger) in most conditions - if its more difficult than that then something is trimmed wrong... I'm not saying we are immune to making those mistakes, but probably more likely to adjust reefs etc if we have an extra "pair of hands".


Can you elaborate on that? I don't, but I might want to in the future. What's the issue with sailing solo?

One of the positive features of the Bavaria steering system is that mechanically it is high geared but still low effort. One of the limitations of the wheel pilot is its slower reaction times compared with a linear drive, but the high gearing offsets that to a point. As many have said it is in heavier conditions where the boat can become unbalanced that it struggles to keep control. This can be improved by reducing sail and therefore slowing the boat down. You quickly learn how to get the best out of the system.

The only limitation for singlehanding that I can see is that you can't control the engagement with a remote . You have to be at the wheel to operate the clutch lever. Apart from that having an autopilot makes singlehanding much easier, particularly when setting sails or doing any deck work.

Remember these wheel drives are fitted to literally hundreds of Bavarias of the type and age of yours, and although not perfect doubt you will find an owner who would want to be without it!

 

[Pete7]

- the "normal" option seems to be a wiper motor, but if I understand the torque correctly would be less than the wheel pilot that people say is only just good enough
- I want the rest of the regular crew (wife/daughter/son) to feel confident using it and they should be able to use the main features without needing to know an IP address or debug why the tablet isn't talking to the pi - its not that unusual to the pi (or perhaps its OpenCPN) to crash.
- having never really used an autopilot, I'd have no real benchmark for whether I was getting good/bad results

I disagree, the RM wheel pilot is an ideal size for a Bav 32. One lever to engage or dis-engage and a button to press to it to auto or stand by. Couldn't be simpler. There are times when the sails won't be balance for example raising, lowering or reefing. We haven't found any short falls when doing this.

If your steering is single finger light and sails trimmed, then the pilot won't have any problems. Do add the rudder reference unit though, makes a big difference.

Pete

 

[ylop]

You just want an autopilot that is 100% reliable.

Madness to buy a cheap autopilot IMO.

I guess my perception of cheap may be different from yours. ~£300 for Pypilot. ~£1600 for wheel pilot. >£3000 for second hand old autopilot with rotary drive. ~ £4500 for the new rotary drive solution. Its likely we sail in different ways too. If I was crossing oceans I'd want a really reliable autopilot (I don't believe any system on a boat is 100%) but we don't make journeys where its not perfectly feasible to hand steer if required. Whilst I can imagine some single handing in the future it certainly won't be prolonged stuff (i.e. < 1 day).

The only limitation for singlehanding that I can see is that you can't control the engagement with a remote . You have to be at the wheel to operate the clutch lever.

Well thats good as the remotes and receivers seem to add another £500 to the price!

Do add the rudder reference unit though, makes a big difference.

OK - that's a clear message which is really useful as I'd likely have skimped a few hundred on that as it is not in the standard package.

 

[ylop]

apologies for slight drift but in case anyone else thinks this happens, if it's openplotter image then crashing is pretty much certain to be a problem on your installation. It should be rock solid. Overheating CPU/inadequate power supply/cheap SD card are by far the most common causes.
Back to the thread....

My working hypothesis is that it is OpenCPN that crashes. It only happens when the screen is asleep and then I can't get it to wake up by tapping key/moving mouse.

 

[GHA]

My working hypothesis is that it is OpenCPN that crashes. It only happens when the screen is asleep and then I can't get it to wake up by tapping key/moving mouse.

Seems unlikely that it's software, openplotter has a very active support forum as does opencpn & apart from local issues it`s a solid reliable combination in use by a great many boats daily. Can't get mine to crash, will try again playing with screen off.

Back to the thread, enough drift, not really relevant here....

 

[MontyMariner]

Can you elaborate on that? I don't, but I might want to in the future. What's the issue with sailing solo?

You need an AP that you can rely on whilst you go to heads, cook, eat etc.

 

[ylop]

You need an AP that you can rely on whilst you go to heads, cook, eat etc.

I don’t think it follows from what others have said that it is inherently unreliable, and when it is going to struggle that seems to be in conditions that are predictable. They are the sort of conditions I would be least likely to be solo in.

 

[KompetentKrew]

Seems unlikely that it's software, openplotter has a very active support forum as does opencpn & apart from local issues it`s a solid reliable combination in use by a great many boats daily. Can't get mine to crash, will try again playing with screen off.

Back to the thread, enough drift, not really relevant here....

I might guess it's a Linux issue with OP's hardware - a kernel module might need loading with a specific setting or something, which would require editing a line in grub.cfg or some other file in /etc.

Obviously we're not in a position to diagnose exactly, but it could easily be neither OpenPlotter's fault nor OP's.

 

[GHA]

I might guess it's a Linux issue with OP's hardware - a kernel module might need loading with a specific setting or something, which would require editing a line in grub.cfg or some other file in /etc.

Obviously we're not in a position to diagnose exactly, but it could easily be neither OpenPlotter's fault nor OP's.

the first reply was mostly in case someone read ..
"its not that unusual to the pi (or perhaps its OpenCPN) to crash." ..
and got the impression that there's something inherently unstable about Raspberry Pi's (running openplotter) or Opencpn. There are very large numbers of systems running out in the wild day in, day out without problems so the platform & opencpn software have earned respect as reliable tools.
Personally I only let Openplotter install any software, that's the whole idea behind it, make sure everything plays nice together. Which it does, you do get frustrated threads on the openplotter support forums which invariably end with "put in new SD card and works fine now" , or new power supply or heatsink. Out of the box the openplotter image does seem very robust & the developers are very keen to hear of any issues which do crop up.

Though in this a Pi just doesn't sound like the right tool for the job, sounds like far better off with something off the shelf.

 

[B27]

the first reply was mostly in case someone read ..
"its not that unusual to the pi (or perhaps its OpenCPN) to crash." ..
and got the impression that there's something inherently unstable about Raspberry Pi's (running openplotter) or Opencpn. There are very large numbers of systems running out in the wild day in, day out without problems so the platform & opencpn software have earned respect as reliable tools.
Personally I only let Openplotter install any software, that's the whole idea behind it, make sure everything plays nice together. Which it does, you do get frustrated threads on the openplotter support forums which invariably end with "put in new SD card and works fine now" , or new power supply or heatsink. Out of the box the openplotter image does seem very robust & the developers are very keen to hear of any issues which do crop up.

Though in this a Pi just doesn't sound like the right tool for the job, sounds like far better off with something off the shelf.

A Pi sounds like an awful lot of processing power for something that only ever needs to drive a DC motor every few seconds.

I used to have a circuit diagram of an early Autohelm, I can't locate it right now, but there wasn't exactly a Cray computer in there!

Maybe something more Arduino would be suitable? It would then be possible to have some sort of self-recovery from any errors?

 

[KompetentKrew]

the first reply was mostly in case someone read ..
"its not that unusual to the pi (or perhaps its OpenCPN) to crash." ..
and got the impression that there's something inherently unstable about Raspberry Pi's (running openplotter) or Opencpn. There are very large numbers of systems running out in the wild day in, day out without problems so the platform & opencpn software have earned respect as reliable tools.
Personally I only let Openplotter install any software, that's the whole idea behind it, make sure everything plays nice together. Which it does, you do get frustrated threads on the openplotter support forums which invariably end with "put in new SD card and works fine now" , or new power supply or heatsink. Out of the box the openplotter image does seem very robust & the developers are very keen to hear of any issues which do crop up.

Though in this a Pi just doesn't sound like the right tool for the job, sounds like far better off with something off the shelf.

Excuse me. Didn't realise it was a Pi.

 

[GHA]

A Pi sounds like an awful lot of processing power for something that only ever needs to drive a DC motor every few seconds.

I used to have a circuit diagram of an early Autohelm, I can't locate it right now, but there wasn't exactly a Cray computer in there!

Maybe something more Arduino would be suitable? It would then be possible to have some sort of self-recovery from any errors?

It needs the processing power, far far more going on than "turn left a bit". Polls a 9doff accelerometer/mag compass / gyro compass 10 times a second just for starters. There's an arduino opto isolated in between the Pi & motor driver to issue commands to the motor driver & rudder position/driver temperature/current draw feedback if fitted.
Probably way more sophisticated control of PID feedback parameters & dozens of variables than most here will ever want, need or even begin to understand.
Though the hardest bit is likely the wiring if building one yourself. Software is solid & easy to install, control can be buttons, web page or opencpn. Follow compass, apparent wind, true wind or gps track/opencpn route.

Give raymarine a load of money and go sailing will likely be a much more sensible option for most people. Though not not as sophisticated control or feedback options. Long distance cruising , the low current & having lots of cheap spares might become more tempting.

pypilot

 

[B27]

It needs the processing power, far far more going on than "turn left a bit". Polls a 9doff accelerometer/mag compass / gyro compass 10 times a second just for starters. There's an arduino opto isolated in between the Pi & motor driver to issue commands to the motor driver & rudder position/driver temperature/current draw feedback if fitted.
Probably way more sophisticated control of PID feedback parameters & dozens of variables than most here will ever want, need or even begin to understand.
Though the hardest bit is likely the wiring if building one yourself. Software is solid & easy to install, control can be buttons, web page or opencpn. Follow compass, apparent wind, true wind or gps track/opencpn route.

Give raymarine a load of money and go sailing will likely be a much more sensible option for most people. Though not not as sophisticated control or feedback options. Long distance cruising , the low current & having lots of cheap spares might become more tempting.

pypilot

When you compare that with e.g. what the chips in a CD player are doing, it's pretty trivial.

The rules for what you want the boat and pilot to do are not tremendously complex.
Modelling a skilled helmsman's handling of sea state is the big problem.
I think that challenges the mainstream suppliers of shiny boxes too.

 

[GHA]

When you compare that with e.g. what the chips in a CD player are doing, it's pretty trivial.

The rules for what you want the boat and pilot to do are not tremendously complex.
Modelling a skilled helmsman's handling of sea state is the big problem.
I think that challenges the mainstream suppliers of shiny boxes too.

runs on a little board costing less than 20 quid -really don't understand what your going on about.

 

[Ed Sned]

Parts of this thread all sounds very familiar...I've had or have most of the drives the OP refers to:
- I had a cable drive in a Mini6.50. Was branded NKE but was made by Octopus, as I believe the B&G unit is. Was driven by a NKE Gyropilot2 computer. I was racing solo so the AP is pretty crucial. I struggled to get it to work that well - drive speed was a bit slow when you're shifting, no doubt because it was a battle to reduce the friction in the cable housing. With that said, most AP's are on the limit in a planing Mini with the big kite up.
- the family then insisted on a boat with a toilet, so we moved to a tiller steered Beneteau. Given the racing had taken a back seat, I went for an affordable US-made Pelagic driving their badged-actuator. Not the most sophisticated brains, but overall, excellent value for money and a bullet-proof ram. Steered nicely to the wind too, albeit the user-interface is pretty basic. Would def recommend this to any small/mid-sized tiller-steered boats.
- current boat is a 37ft trimaran which I'm back to racing solo offshore. It's frustratingly wheel-steered and came with the Raymarine wheel-drive ST4000 AP linked to 2016-era Raymarine instruments. I used that set up for about a year, but found the wheel pilot very flimsy and not confidence-inducing at all. It regularly stopped working, with the issues generally being the entirely plastic parts that regularly broke. To be fair, I suspect it was old and had taken a lot of UV. I also had to change the motor, which is quite exposed to the elements. I found the Raymarine wind wand a bit crude too. I also wanted a remote control.
Hence I ended up skipping much of it and now have NKE wind instruments, compass and autopilot (Gyropilot3), which are linked in through the NKE 2K box into my newish Raymarine Axiom MFD and the original i50/i60 displays, which I really like. Essentially there is a NKE topline network and a parallel RM STNG network which are linked in the middle. I also have separate AIS, HF GPS and a few other toys feeding into the system. The AP now drives a Jefa sprocket drive mounted under the steering pedestal. Control of the AP is by a NKE Multigraphic on the pedestal, although I also have a remote control
It sadly cost a small fortune and in places, has taken a fair bit of ingenuity to get it all to work together (I'm now an expert on PWM frequencies, signal chokes, solid-state relays etc). However, I wanted a system that was as bullet proof as an AP system can be, and would last and not need replacing for a good while. Finally, I wanted something where I fully understood the install (I've done it all myself) so that I can de-bug it in the middle of the Atlantic if needed. Recognise this may be a far cry from the OP's question, other than it's worth thinking about how much you want to be able to rely on it. If it's just so you don't have to stand at the wheel all the time but are otherwise awake and nearby, and you don't expect to be pushing the boat in wild conditions, then you don't need too much. However, if you plan to get any sleep, or to be pushing hard with the kite up, then you may need something more solid and trustworthy than the RM wheeldrive. Horses for courses as always.

 

[fredrussell]

Interesting post Ed - there’s very little chat of NKE gear on this forum but from my reading on US forums it would seem to be the gold standard in autopilots. I think it’s primarily aimed at racing boats, is it user friendly in terms of user interface and ease of operation?