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Starting from sctatch
#1
Hi everyone,
     New to the forum but have been "playing" with OpenCPN for a few years and I believe it is mature enough to run as the primary Nav/Data/Control system on a crusing boat. I live in Germany but have bought a SailBoat in the US and am heading over in Jan. 22 to start a refit. I'm going to strip all of the electrics (12v/110v) out of the boat and redo it in 24v/230v. All of the Plotters and "electronic stuff" on the boat is 15+ years old and I have no desire to replace it with commercial options. I want to rebuild the boat using OpenCPN/Openplotter/PyPilot etc...and RPi's. I was really impressed with Seans Pypilot Video and also the work that others on this Forum have done with Pypilot.
 
     I'm a real DIY kind of Guy and love building things myself (even it it costs more in the end than a Commercial equivalent  Wink ). I'm a Prototype Engineer in the Aircraft industry so I definitely fall into the "Hardware" category not so much the "Software" side. I'm planning on purchacing a complete setup from Sean as soon as I get to the US so I'm trying to get a "List" started as to what components I'll need. As for the Software side I hope I'll be able to call on the expertise of this group for any help.

     I am planning to set up the Autopilot like I saw in the Video from Sean on the Steel sailboatboat. I would like a similar Motor and Wheel setup rather than a Quadrant system with Linear Drives. I like the Idea of the Windshield Wiper motor because they are readily available anywhwere. A question I have about the Wiper motor is: Do you have to modify the motor in some way or will "Off the shelf" work? My Boat is a 46 ft Center cockpit Ketch and about 16t. Any recomendations as to Wiper motors or (I assume) DC motors that would work?

     I really want to set the boat up completely with RPi. I think I will probably have to have multiple Rpi's so as not to overload a single unit. I'm thinking that I'll run each subsystem (Pypilot, OpenCPN for Nav/Radar/AIS, Boat info, Environmental info etc...) on its own RPi and then combine all the data (through SignalK ?) into a central monitor (at the Nav Station) and a remote monitor (under the Sprayhood/Dodger). Am I making this to complicated? I'm used to building in redundancy and ease of subsystem replacement/repair so I dont know if I would be going overboard having each subsystem going to it's own RPi. I definately don't want a complicated system that will take a Degree in Software engineering to set up and would be fairly easy to Repair/replace when I'm sitting somewhere in the Tuamotus or the Solomons...

     Anyway, before this post gets too long, I'll leave it there. A hardy Thank you in advance for any advice.

Many thanks,
Rick
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#2
If pypilot somehow costs more in the end of a "commercial equivalent" I would really like to know about it. I guess technically if you buy parts for pypilot it is also commercial.

As mentioned on the forum earlier, the power steering motors are a step up from windshield wiper motors in terms of power, but they do cost a bit more. Most wiper motors will work fine, the thing to look for is universal vs fixed magnet. Only really old ones are universal as far as I know (1970s and before), and although maybe slightly more powerful, they use at least twice as much power which is bad.

I intend for pypilot to be able to run on its own pi using the tinypilot image and distribution. This gives the best reliability because tinycore linux runs completely from ram. It is unfortunately not supported on pi4 just yet however if you intended to use all of the same type of pi, but I should have this in not-too-distant future.
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#3
(2021-08-14, 06:28 PM)seandepagnier Wrote: If pypilot somehow costs more in the end of a "commercial equivalent" I would really like to know about it.    I guess technically if you buy parts for pypilot it is also commercial.

As mentioned on the forum earlier, the power steering motors are a step up from windshield wiper motors in terms of power, but they do cost a bit more.   Most wiper motors will work fine, the thing to look for is universal vs fixed magnet.   Only really old ones are universal as far as I know (1970s and before), and although maybe slightly more powerful, they use at least twice as much power which is bad.

I intend for pypilot to be able to run on its own pi using the tinypilot image and distribution.   This gives the best reliability because tinycore linux runs completely from ram.    It is unfortunately not supported on pi4 just yet however if you intended to use all of the same type of pi, but I should have this in not-too-distant future.

Super, Thanks for the info. I wasn't meaning PyPilot was going to cost more than the Commercial equiv...but in the past I've been known to DIY some things that in the end would have been cheaper to buy off the shelf...but I had the satisfaction of building it myself and knowing exactly how it was built and how it works. That's worth more to me than anything... Big Grin .

    When you say Power steering Motors you mean an electric motor for an Automobile Power steering pump? I don't remember seeing anything about these in a thread (it could be that I just haven't found it yet). I'm relatively new to the Forum (only found it last week from your YT Videos via an OpenCPN thread on the Cruisers Forum). Are there any particular Wiper/PS motors you can recommend? I assume the larger the Boat the Larger (or Stronger) the motor needs to be.
 
     As to the RPi's, yes I was planning to use the Pi4's with SSD's at this point unless a newer, better model comes out before Feb. (when I plan to start the Refit). Yeah, I really like your system because it functions as a standalone but can be intergrated into OpenCPN. The setup that Ironman and Andreas29 have built as well as your own tests convinced me that this is a viable alternative.
   
     I'm sailing the boat from the US and plan to hang out in and around the South Pacific for a few years so it'll be a good long term trial for the technology/systems. I'm a big believer in being able to source "universally available" components and giving the Stink finger to the guys who try to control a particular portion of the market. I think this is going to be an interesting project.

Rick

Edit: I found some threads on the EPS motors....Nice...
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#4
I understand, but also when you build yourself you have something usually better that you can fix for cheaper. In the case of pypilot it is going to be a lot cheaper though, unless you get a used system but that is unlikely to be cheaper and it will not be very good.

I dont mean for a power steering pump, although maybe it can work, but actual just electric power steering motor. Ted Coats has this, see his posts on pages 2,3,4
https://forum.openmarine.net/showthread....=ted+coats

I used a motor from F-150 truck but there are only a few models in many vehicles. They are all fairly similar in power. In junkyard here they are $6 each because they have no value since they never burn out no one wants them for parts.

It costs a lot to ship to south pacific except american samoa which is very cheap. So I suggest having redundancy. Even just having extra imu sensors as cheapest option, and since you have many spare pi already you will automatically have the ability to build a complete autopilot backup computer. The regular motor controller I produce can drive wiper motors fine, but larger motors may need the larger controller. I am not sure about the power steering motors current requirements, but I know Ted has the larger motor controller, not sure it is required or not.
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#5
I see what you're talking about now...The electric steering assist...got it...Yeah, the Ted Coats setup is kind of what I'm after, a Drive motor attached to the Steering Pedestal using a Belt and then some kind of quick disconnect lever. I agree wholeheartedly about redundancy and these systems based on Rpi's, Adurino etc...makes it possible to to have several backups at a reasonable cost. It'll be interesting to see how the Pi's and it's peripheries hold up over the long term in the Marine environment.

I'm still kind of Grey about the relationship between OpenPlotter and OpenCPN...I guess I had it in my head that it was the same thing. In order to run Pypilot do I need OpenPlotter in addition to OpenCPN? or is Open Plotter the Pi version of OpenCPN? I have OpenCPN on my PC. Like I said I'm not really a "Software Guy", I'm a Software user...I have never programed anything, that's why I'm hoping everything will intergrate fairly seamlessly with each other. I realize the SignalK will involve some programming but hopefully it won't be too difficult. I've watched a bunch of YT Videos about SignalK and Sailboats so I might be able to muddle my way through it.

I think I read somwhere (not sure it was here or someplace else) where it was suggested it was better and more reliable to interconnect these systems with a LAN network rather than WiFi? Any suggestions/recommendations?
Many thanks,

Rick
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#6
openplotter is a collection of scripts that facilitate installing and managing various applications useful on boats. One such application is OpenCPN, another signalk, and another pypilot. There are many more. It is especially targeted for raspberry pi but other hardware can be used.

I do not think a wired lan is much more reliable but consider wifi can hiccup at times so I keep wifi out of the control loop. For example you can send wind data over wifi to pypilot on a separate pi, but it may lag a bit. Generally the compass is used to fill the gaps as pypilot follows a compass course which is adjusted to match the desired wind angle in the basic pilot, but it depends on the algorithm selected. With the wind pilot (which ignores compass) it would matter, but in this case it would be recommended to feed wind directly to the pi running pypilot, and the wind data is then relayed over wifi for use in instruments.

So it really depends on what you are trying to do, but general wifi works ok and is a lot easier to set up.
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