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Old 21-12-2018, 23:17   #31
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Re: Autopilot from scratch

I posted this a few days ago on another thread about converting a linear drive to rotary.

The difficult part of DIY autopilots is the electronics, the mechanical parts are a piece of cake.

The image is of the second or third attempt at converting a Raymarine ST4000 from an unreliable and expensive toy into a cheap and reliable, if a bit agricultural, autopilot.

The first attempt involved the emergency repair of the wheel drive by using the gearbox from a cheap Chinese battery screw driver to replace the Raymarine box which had tiny nylon gears which stripped.

The second got rid of the 7 mm wide belt and used the gearboxes out of two cheap Chinese battery drills to increase the torque output. The 7 mm belt was replaced by a 25 mm wide auto timing belt for which I made a sprocket out of alloy using a drill press and small lathe. The wheel drum was made from a Regal cookware frying pan and I have to say it did a hell of a lot better job as an autopilot part than it ever did as a cooking utensil.

The third is the one in the image which used a 24V electric bike motor to drive a bike chain reduction and a larger sprocket driving the timing belt. By this transition I had got it down to pretty well bullet proof. The 300 watt 24 volt motor running on 12 volt provided sufficient torque and was derated enough to blow the fuse before any damage to the motor.

My new boat has a Simrad hydraulic drive autopilot and whilst it is extremely well made and appears reliable after about 6,000 nm of coastal cruising I don't get anywhere near as much gratification from it as I did from the agricultural DIY job.

If you are handy with tools this is probably your best solution.

If you go the DIY route a good source of motors is the ones from aftermarket 12V radiator fans.

I highly recommend Regal cookware as suppliers of wheel drums (I actually emailed the president of Regal complimenting him on the utility of his frypans but the curmudgeonly beggar declined to answer)

12 mm pushbike chain and sprockets are readily available and the larger sprockets required are easily made from alloy plate on a drill press.

I used the timing belts with semi circular teeth as it made the sprockets easy to manufacture.

On the left hand side beside the drum is a lever in the disengaged position which lifts the motor and loosens the belt which then slides on the drum allowing hand steering. The lever and push rod are made out of scrap pieces of alloy section and solid rod respectively.

The brackets which hold the drum onto the wheel spokes are made from scrap alloy angle iron. I used the original Raymarine mounting brackets but they were plastic and the sun eventually got them.
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Old 21-12-2018, 23:44   #32
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Re: Autopilot from scratch

RR, all I can say is that I really like your approach to this problem, and applaud your success!

Very well done!

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Old 22-12-2018, 07:13   #33
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Re: Autopilot from scratch

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Originally Posted by Jim Cate View Post
RR, all I can say is that I really like your approach to this problem, and applaud your success!

Very well done!

Jim
Ditto! I love your solution, very creative.

Rob
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Old 22-12-2018, 07:43   #34
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Quote:
Originally Posted by gmakhs View Post
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 .
This is the first I've heard of a trim-tab windvane. I did a short Google on it, and the ones I'm seeing off the hop are for transom mounted rudders. My rudder is at least 3' forward of the transom. I think I've got more research to do
I really do love to windvane solution, and if I can afford installing one before we go south, I will definitely consider it. But in the meantime, all of our cruising in the next 6 years or so will be on the Great Lakes, and from my limited understanding, the winds around here are generally just too variable to use one. Once we get out into salt water, and trade winds. I love the fact that windvanes are quiet, reliable and don't use power.
From my limited understanding, windvanes are great in decent winds, but in lighter variable winds, a conventional electric autopilot is the only option (other than hand steering of course).
Saying that, I am totally open to the idea. If you know of any systems that would drive my lump of steel, or would like to enlighten me more, I'd love to hear it.
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Old 22-12-2018, 08:03   #35
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Re: Autopilot from scratch

I don't know of any commercial trimtab windvane , but manufacturing one with the auxiliary rudder should not cost more than 2000.
If your rudder is always behind the transform you add it to your current setup for a lot less (hardly 500)
The benefit of the trimtab is that you can use it with an electric tiller pilot (in the place of the vane )and will steer your boat without the pilot bearing its weight.

I have seen autohelm.st1000 drives steer 12 tonnes with this setup .

I have been suffering with most of the commercial solutions on my boat , so take good thinking on what and how you gonna setup it you need reliability simplicity and repairability.

When I was planning to buy a steel boat I had in my plans to add a seccond rudder made out of balsa or.foam fiberglass core and add to stern .
That way you steer the boat with the auxiliary rudder when underway with windvane or electric tiller drive and you lock the main rudder in straight position.

But I do t know how you boat is designed so this is something you will have to work by yourself
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Old 22-12-2018, 08:25   #36
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Re: Autopilot from scratch

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Originally Posted by gmakhs View Post
I don't know of any commercial trimtab windvane , but manufacturing one with the auxiliary rudder should not cost more than 2000.
If your rudder is always behind the transform you add it to your current setup for a lot less (hardly 500)
The benefit of the trimtab is that you can use it with an electric tiller pilot (in the place of the vane )and will steer your boat without the pilot bearing its weight.

I have seen autohelm.st1000 drives steer 12 tonnes with this setup .

I have been suffering with most of the commercial solutions on my boat , so take good thinking on what and how you gonna setup it you need reliability simplicity and repairability.

When I was planning to buy a steel boat I had in my plans to add a seccond rudder made out of balsa or.foam fiberglass core and add to stern .
That way you steer the boat with the auxiliary rudder when underway with windvane or electric tiller drive and you lock the main rudder in straight position.

But I do t know how you boat is designed so this is something you will have to work by yourself
Very interesting idea... Looks like I got some learnin' to do

Any suggestions on where to start? I've got a haulout to do in the spring, so at that point I can take pics, and measurements, and maybe with a little help come up with some practical ideas, and options.
Hell, if I've got some rudder or auxilliary rudder work to do, maybe I can even address her inability to reverse in a straight line. Right now, she's got so much prop-walk when reversing that even backing into a slip is near impossible.
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Old 22-12-2018, 10:21   #37
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Re: Autopilot from scratch

As far as roll your own goes, Sean D'Epagnier (BoatAlexander on CF) has a really nifty DIY autopilot. He even sells the processor boards, I think. It's quite a nice bit of software. A link to his site is ->pypilot - open source marine autopilot.


I being a retired engineer, decided to DIY also. But I did mine from scratch as I wanted a bit more of a fun challenge.... I'm weird.. Right now it's at the Autohelm 3000-4000 level, plan jane really. Took a month to build and program, including teaching myself python. I'm mess'n with the code a bit this winter.



The electronics are actually fairly easy. A Raspberry PI or Arduino micro controller add a bit of C or python programming and a wheel drive or linear drive and bob's your uncle.


Sean has the two boards and software for less then $200. His software is very very good and allows for wireless remote, Rudder position sensor ($35), wind sensor, GPS, etc. etc., talks to OpenCPN, etc. It has ALL the bells and whistles. Really the software is better then anything on the market. Some assembly required. OK LOTS of assembly required.



I built a much simpler AP for about $110 for parts and used my old Autohelm 3000 wheel drive motor. Mind you I already knew three other programming languages and has built control systems from component parts back in the 90's for fun. The PI or Arduino's make that pretty easy (for the engineer).


A linear drive to connect to the quadrant, would be about $300 for the motor, one to match RayMarine's $1600 version.




So it can be done and for not lots of $$$.
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Old 23-12-2018, 02:18   #38
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Re: Autopilot from scratch

Thanks folks, I'm a fiddler by nature and it's great when your recreational activities can complement your voyaging requirements.

I've noticed you do like a challenge sailorchic and one cannot ask for more in a woman than skill with wrench, soldering iron and keyboard.
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Old 23-12-2018, 10:01   #39
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Re: Autopilot from scratch

Quote:
Originally Posted by sailorchic34 View Post
As far as roll your own goes, Sean D'Epagnier (BoatAlexander on CF) has a really nifty DIY autopilot. He even sells the processor boards, I think. It's quite a nice bit of software. A link to his site is ->pypilot - open source marine autopilot.


I being a retired engineer, decided to DIY also. But I did mine from scratch as I wanted a bit more of a fun challenge.... I'm weird.. Right now it's at the Autohelm 3000-4000 level, plan jane really. Took a month to build and program, including teaching myself python. I'm mess'n with the code a bit this winter.



The electronics are actually fairly easy. A Raspberry PI or Arduino micro controller add a bit of C or python programming and a wheel drive or linear drive and bob's your uncle.


Sean has the two boards and software for less then $200. His software is very very good and allows for wireless remote, Rudder position sensor ($35), wind sensor, GPS, etc. etc., talks to OpenCPN, etc. It has ALL the bells and whistles. Really the software is better then anything on the market. Some assembly required. OK LOTS of assembly required.



I built a much simpler AP for about $110 for parts and used my old Autohelm 3000 wheel drive motor. Mind you I already knew three other programming languages and has built control systems from component parts back in the 90's for fun. The PI or Arduino's make that pretty easy (for the engineer).


A linear drive to connect to the quadrant, would be about $300 for the motor, one to match RayMarine's $1600 version.




So it can be done and for not lots of $$$.
Cool, thanks. At least I've got a place to start.
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Old 31-12-2018, 07:14   #40
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Re: Autopilot from scratch

Link did not work..... how do I find Paul and/or pypilot?
Thanks
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Old 31-12-2018, 07:43   #41
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Re: Autopilot from scratch

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Link did not work..... how do I find Paul and/or pypilot?
Thanks
Sent a note to Sean telling him the pypilot.org site is down.

Over the summer Sean developed a high amp controller (>30 amp peak power) to run our hydraulic AP pump. We have tested it extensively with his AP software and will say it works remarkably well. It also has very low power consumption.

I'm hoping in the next few weeks to have a blog article up describing our set up.

Bottom line, I would highly recommend Sean's AP. The software for the Pypilot is included in the free OpenPlotter software. He has tested it with a tiller, wheel pilot (replaced a CPT) and now a below deck hydraulic.


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Old 31-12-2018, 14:06   #42
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Re: Autopilot from scratch

My Flicka has a tiller so the steering is pretty straight forward. I thought Cape Horn wind vanes looked attractive because they are completely independent of the rudder. If I were interested in redundancy and simplicity that’s the one I’d look at first. I don’t have one yet so I can’t speak from first hand knowledge.
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Old 31-12-2018, 14:33   #43
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Re: Autopilot from scratch

How do you contact Sean (Pypilot)? His site seems to be down and there is no BoatAlexander in the membership listings...
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Old 31-12-2018, 14:46   #44
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Re: Autopilot from scratch

You can contact Sean through his forum That seems to be working.

OpenMarine - Pypilot


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Old 31-12-2018, 15:32   #45
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Re: Autopilot from scratch

Thank you!
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