How to use the Trident display to full advantage


Could someone explain in detail the function of the compass ring in the pilot view of the Trident? The little arrow for example… How do you best use it in order to know where you are/what direction you’re travelling?

I guess I might figure it out eventually but for now I’m more focused on what I see and piloting the ROV and so I haven’t really been using it to it’s full advantage (I suspect).


The ring is actually jut a compass and the little arrow is the trident’s current heading. At 0° it heads north, 90° it heads east, 180° south etc…
You may want to have a second compass at hand to know where north is so you can have a better idea in what direction you’re looking at the surface and then determine the Trident’s orientation.


Thanks! I guess that’s what I figured. Just been to busy focusing on learning the controls to confirm it.
Having an extra compass on shore is a great idea!


When you turn it on, have the ROV pointed north and it will be true to a compass.


If you hold the tether taught and go full thrust for a moment, you should be able to examine the heading, then do a three point turn, backing up to slack the line, and head back to the operator by going 180 degrees from previous heading. Thanks boatsd for the calibration tip…


Doesn’t it auto calibrate?


I thought the big arrow was Tridents heading and small arrow was the direction your control device was pointing.


To say it in other words : when you start the Trident, the direction his nose is heading is considered as north. I think the best way is not to consider the real coordinates but to place the Trident with his nose looking in the direction you will navigate then start it. By doing this if you always know where you are and which heading you have to take to come back to the strand, maybe more right or left but nevertheless to the strand.


Really?. Gotta check.
I had the impression that it actually gave true magnetic north no matter how it was oriented on powering up.


I am in agreement with that. The compass on board Trident gives true magnetic. The small compass arrow on the cockpit screen is your controller (tablet, phone) orientation and for me the top of my tablet is the north.

What would be GREAT is if there was a way to see the part of the Trident theater that is floating on the surface along with the controller device GPS location plotting on a map. This is similar to navigation aids on aerial drones. I believe that the FiFish P3 has this feature from what I have seen in reviews and looks to be a great navigation aid.


Strange … In cockpit view I have only one arrow !


I second marcolinger. One arrow only in my cockpit view.
I checked what was written above and do confirm that this arrow actually just points straight ahead on powering up the trident. It is not true magnetical north.
This actually easily allows for different navigational uses, so it is a good thing!


I have two arrows… One showing the direction I (the tablet) am facing and one showing where the Trident is facing.
Different software versions?


Hey all! If the device you’re using has a built in compass (tablets as well as the Trident controller don’t but phones often do) then an additional arrow will show up that indicates the direction that device is pointing for reference. For devices without an internal compass, the reference arrow won’t appear. The larger vehicle arrow for Trident is linked to a magnetometer on-board the vehicle that detects magnetic north and also fuses that data with a rate gyro. In order for this system to work well, the vehicle usually needs to be calibrated. To do this, I recommend (before starting your dive) rotating the vehicle back and forth about each of its three axis several times. This will allow the magnetometer to detect where north is and ignore other magnificent fields. We’re still catching up on documentation, but we hope to have a tutorial for all this stuff sometime soon. Thank you everyone for helping each-other get this stuff figured out in the meantime!


Thanks for clearing that up Eric!
Apparently I have a built in compass in my Sony tablet… Who knew!


I realy appreciate your comment Eric. On my dive today, I used your instructions, and were finally able to use the direction arrow the correct way.

If you or someone else from openrov, could send out a qick draft of a user manual for the Trident app, I think it would benefit all of us in the long run. With better knowledge about how it is supposed to work, it is easier to give correct feedback regarding improvements.

With that said, you guys (and girls) have made an excellent ROV for the consumer market :blush:


I totally agree with oddgeir !

It would also be interesting to have one common adress where early users could send their recommendations for new users. I mean this type of remarks :

  • importance of cleaning and WD-40after dive,
  • start with low speed as the Trident can be verry fast,
  • no water or else in the Trident connection hole,


Thanks for the info.
I recently had the chance to test the TRIDENT at sea for the first time in a proper way. Reading this tread of posts I understood that the Trident need to be calibrated before a dive. I did spin the rov around the 3 axes and the heading I read on the singularity pad seems to agree with analogical compass directions. However I noticed that as soon as I put the rov in the water and I start diving the heading readings become unreliable.

After some trials I had the impression that when the trident change inclination, mainly up and down, the heading is altered even if i did not change the direction compared to the north. This basically happen almost all the time since I frequently need to adjust the pitch (up and down) even when moving left and right.

Today I tested it again and what I noticed is that, even if calibrated, at some point the reading on the compass go off. However when I retrieved it was still point north correctly.
If I do not calibrate it, as someone was proposing here, the heading go off pretty soon.

The consequence is that I can’t really figure out where I’m going and I end up doing random dives.

Is this a problem just of my unit or It’s me doing something wrong?
Any fix?

Thank you very much.



I suspect that the magnetic fields generated by the Trident’s thruster motors are influencing the compass on the Trident especially the magnetic field of the vertical thruster. I have seen the same thing happen with the compass in the IMU module on my OROV2.8.

This peculiarity has been discussed to some extent about the IMU module that is available for the OROV2.x. The understanding was that when the thrusters are operational the IMU module will use the gyro/accels for heading and then revert back to the compass when the thrusters are off and no magnetic fields are being generated by the thruster motors.