Sailboat Support

Thank you for your responce.

I took a video. As can be seen in the video, when in Acro mode, the elevator trim does not move in response to the direction of the windvane.

The servo for elevator is connected to servo CH4

I see you have the motoring switch setup on RC 8, since the motor is going I guess it is high. With RC 8 low it should only use the sail and disable the motor.

I turned the motor assist switch to Low and tried again. However, the sail only works in manual mode.

When I try to move the weather vane from port to starboard and vice versa in Acro mode (ARMed), I don’t see any elevator trim movement.

After this, I disabled the RC8 motor assist, but the situation is the same. I am currently using Ardurover FW 4.2 (for F405 wing).

Do you have any good ideas for the solution?
Thanks again.

I attached latest param file.

A log would be more useful that just a param file.

I’m not sure what is going on, I’m not aware of any changes that would have broken this functionality.

I hadn’t used my boat in a while, so today I sent N4N1 on a course that circumnavigated Saildrone Surveyor (on her mooring). I’ll edit the video soon. Worked well enough to go twice around but not a great driver in the gusts (on a path with lots of reaching) – I think I will try enabling the heel control PID. The integrator on rudder eventually gets it but I had some big transient wiggles.


Nice! Really gives a idea of the scale.

Can we claim: Ardupilot sails rings around Saildrone ?


Is there a way of setting the Sailboat motoring 3 position switch function from lua, I want to control the switch based on main battery voltage, so above 12v it will just use the motor, 10.5-12v will sail with motor assist then it will only sail once its under 10.5v.

Yes, probably only on tho.

rc:run_aux_function(74, 0) -- never use motor
rc:run_aux_function(74, 2) -- always use motor
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Yes I can use motor easily with the aux functions, but those are binary, that would remove the option for motor assist, it’s the most important one out of them all, so I need all 3 modes.

You can do assist with:

rc:run_aux_function(74, 1) -- assist
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Sorry I misunderstood you, ok that’s exactly what I’m looking for thank you.

I tried using the button test script to test it and it doesnt seem to do anything, im not getting any errors but im not getting the message that its changed sailing modes either

batterysail.lua (802 Bytes)

After a lot of testing, I found that this problem does not occur when I retry with the old parameters (00000026.BIN). Then I tried to run the same FC with the same parameter that had the problem and the elevator did not work properly in ACRO mode (00000026.BIN). Originally this problem occurred when I refurbished a new identical FC and wrote the old parameters. Since the two parameters are the same, I am now suspecting a faulty FC or a failed firmware installation.

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I have been doing some testing with the motorsailing setup, and from my testing all the sailing switch does is disable forward propulsion, transverse omni thrusters and left right motor yaw control stays online they just cant propel the boat forwards or backwards. Ideally, there should be a mask to select what motor gets disabled rather than just inhibiting forward thrust.

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Yep, we should fix that, your breaking new ground with a omni sailboat.


I’m about to start a sailboat build and had a quick question about wing sail elevator hardware:
Does the wing sail need to be able to rotate completely freely with a slip ring to pass servo signal through for unlimited rotations? Or can it be restricted to 180 degrees of rotation?

My concern was that it might get stuck to one side when turning downwind. I don’t have any experience with this so I’m not sure if this is a valid concern.


Restricting the rotation should be fine, the limitation will be the distance you have to turn before the wind catches the other side of the elevator and snaps it through the 180 deg. Of course this is the same problem that we have with boats with normal sails and they get on OK.

Excuse the bad diagram.

At point 1 your all good, the wing is not on the limit.

At 2 and 3 its on the limit, but this works well as it presents a big surface area where drag is driving you along

Case 4 is the bad one, its still stuck on the limit. But the airfoil is working backwards and because its on the limit you have no control over it. Really it should be on the other side of the boat.

Case 5 your OK again, you have turned far enough that elevator has passed through the wind and the sail has done that 180 swap on to the correct side of the boat again.

Once you have hit number 5 you can turn down wind again back to the same direction as case 4 and it will be OK again.

Depending on the angles your sailing and where the limits end up it may or may-not be a issue in real life. AP is not clever enough to do anything to help, but you could program downwind missions to head up to case 5 before turning back to 4 to avoid this case.

There is no issue when turning the boat into the wind.

Looking forward to seeing it! Happy to help if you need any pointers.


I agree with Pete. I also think it would be slow to have the wing sail trimmed for lift (vs max drag) going downwind, so limiting the rotation is probably faster.

I think keeping the rig light for this rotation could be important, when the sail hits the stop on the other jibe it can throw your boat into a big transient.

Here’s a clip of my boat jibing like Peter describes, not a wing sail though. (link supposed to go to 15:05)

Thanks Peter and Mike! Is 180 degrees of freedom the optimal amount? Or is there any benefit to a little more or less?

Still in the early stages of the build but here’s what I’ve got so far!

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