Launch and return to boat

[Hobbo]

I've got a Mavic Air so as MJBok has clarified, I won't have the choice of even taking off its displaying "compass error". If I can find a spot on the boat (its biggish) that I can get the compass to calibrate, then I could fly BUT if I loose connection, and the RTH is enabled, the MA will be lost if the boat has moved.

MJBok, you mentioned "updating the RTH" - is that something you have to do manually do as the launch position moves? (because the MA doesn't do it automatically does it?)

 

[RTKD]

Although you don't want to have your drone returning and landing on a boat, RTH is extremely reliable.
Do you have a particular reason for not trusting it?

You know I really don't. I understand that it is / should be as reliable as the GPS coordinates it has, but I just don't like the idea. Everywhere I fly is around trees, and I love to fly around or below the treetops. I know you can st the RTH height, but I just don't trust those sensors to bring my bird home. I can admit now even as I'm talking about it that my fear goes a little to far. I can't help but picture my Mavic turning towards Shenzhen and heading off into the sunset.

MJBok, you mentioned "updating the RTH" - is that something you have to do manually do as the launch position moves? (because the MA doesn't do it automatically does it?)

I have a Mavic Pro, but there's a setting to update RTH location. If that box is checked it returns to the controller location, not the location that you took off from

[EDIT] Looks like dynamic RTH might not be available for the MA right now. Here's the DJI thread:
Mavic Air Dynamic Home Point

 

[DanMan32]

If you don't have a landing site clear of sky obstructions, then indeed RTH won't work well.

If you're getting compass errors on the boat, your only option is to hand launch or don't fly from the boat at all. Calibrating in an area not free of magnetic interference is asking for BIG trouble.

 

[MrRobville]

This may be an odd idea, but perhaps you could reprogram the sports mode switch into an atti mode switch and fly using atti mode instead. If I recall correctly, atti mode does not utilize the compass.
The downside is though, you need to be more experienced into controlling your quad as there is no GPS lock either, thus no Return to Home.

I once made a topic on how to reprogram the sports mode switch:
Sports mode to Atti mode?

 

[Meta4]

If I recall correctly, atti mode does not utilize the compass.

In Atti mode the drone does not use GPS for position holding.
The compass is still used.

 

[Meta4]

You know I really don't. I understand that it is / should be as reliable as the GPS coordinates it has, but I just don't like the idea. Everywhere I fly is around trees, and I love to fly around or below the treetops. I know you can st the RTH height, but I just don't trust those sensors to bring my bird home. I can admit now even as I'm talking about it that my fear goes a little to far. I can't help but picture my Mavic turning towards Shenzhen and heading off into the sunset.

This is a common fear for people that haven't experimented with RTH to find out how it works and what it does.
Not trying out RTH is a mistake since the day you need RTH is the worst day to start learning it.
Give it a good workout in a large open area and you'll get a lot more confidence.

 

[MrRobville]

In Atti mode the drone does not use GPS for position holding.
The compass is still used.

I see. Though active, the compass is no longer used for positioning right? Considering Atti mode is used whenever the quad goes haywire in GPS mode.
In that case one would still be able to fly the quad regardless of magnetic interference.

 

[tcope]

Flying from a boat is a very advanced flight. If you lack a lot of experience flying, it becomes more likely that you will lose the Mavic. For example, you say you won't use RTH. However, RTH kicks in if for some reason the controller disconnects from the Mavic. You simply have almost no control over this. It could easily happen when the drone is a few feet away. After all... what could go wrong with radio signals on an all metal boat surrounded by water. You don't seem interested or understand what happens then. What happens is the Mavic goes back to the launch point... which, with a drifting boat, is now above water... and lands. So you now have a Mavic in "fly away mode' (which usually means someone has not read the manual) and it lands in the water. First thing to do when flying from a boat is change RTH to Hover. Second thing is to understand that any flight from a boat _greatly_ increases the chance that you will lose the drone and that this chance increases with lack of experience. As another example... and as people have already mentioned, how do you plan on landing on a drifting/moving landing spot?

BTW, IMHO Meta is nailing all of the problems.

 

[Meta4]

Flying from a boat is a very advanced flight. If you lack a lot of experience flying, it becomes more likely that you will lose the Mavic.

I can't over-emphasise how much trickier everything is out on the water and how important it is to be able to do everything you have to without thinking about it.
Definitely start on a slow-moving boat if you want to try it.

BTW, IMHO Meta is nailing all of the problems.

Thanks .... I've had a little experience with the topic. Most of my drone photo missions are either of or from ships and boats.
Here are a couple of shots from well offshore, much too far to be able to fly back to land.

 

[Meta4]

I see. Though active, the compass is no longer used for positioning right?

The compass is never used for positioning.
It provides direction information - not position, which comes from the GPS.

Considering Atti mode is used whenever the quad goes haywire in GPS mode.
In that case one would still be able to fly the quad regardless of magnetic interference.

Atti mode is what you have when you either lose GPS or the flight controller ignores GPS due to compass issues.
If you have serious compass issues such as a yaw error induced by launching from a steel or reinforced concrete surface, all bets are off and your flight could end badly.

 

[swooshdave]

I believe I've read (but not tested) that the downward facing sensors don't like to look at water. Something else to turn off.

 

[tcope]

I believe I've read (but not tested) that the downward facing sensors don't like to look at water. Something else to turn off.

Most likely a throwback to P3 and before days. Downward facing sensors no longer control altitude unless in Terrain or Active Track mode.

 

[ScubaBob]

Hi I'm planning an outing on a friend's 50 foot aluminium boat - plenty of steel as well no doubt. I expect I'll be able to lock into ~10 - 15 satellites but not sure about compass calibration. If I have clear viability; no wind etc am I going to be able to operate without risk of rogue flyaway etc - I'm not for example wether the controller will allow me to fly if steel upsets the compass? Thanks

This is not related to your compass issue but is related to launching and retrieving by boat as I have done that a lot of times. First, practice a lot on land with hand take-offs and retrievals. Second, turn off downward sensors. Third, Set your maximum distance to something like 5,000 meters. Here is why. You launch from point A and send your drone to point B. But your boat is probably drifting and the drone measures distance from the home spot--not where you are unless you have the "follow me" setting turned on and even then, the boat is always moving. The point is that one time when I was out and had my distance set for 500 meters I could not get the drone to come back to the boat even though it was less than 200 meters from me because I was 600 meters from the place where we launched. So be careful and practice a lot and you should be fine.

 

[radmanzulu]

If you calibrate your compass on shore, you will be fine. Remember there may be other large ferrous objects on a 50 foot boat - like an engine block. As to whether you should calibrate your compass from time to time, I would trust the engineer who designed your drone and ignore random advice that you get on this forum. The answer is yes if you move the drone a significant distance - think over 100 miles.

Your flight setup screen allows you to choose whether the drone should consider where it took off as home or whether it should use the location of the remote controller. If you choose the remote controller, it will automatically keep updating the location of home as the controller moves. Be aware that if the RC loses connection with the drone, the drone will use the last known location which may be off if you move the boat a considerable distance while the connection is lost. This is not as big a problem as it sounds, over water there should not be connection issues and if there is, the drone should reacquire if you are close to the last known position. Remember, if the wind is blowing to fly upwind first or you may experience range issues coming home.

Don’t take off while the boat is moving unless you hand launch. The drone will auto hover in one spot in relation to the earth (not the boat) and some part of the after part of the boat may drive into it since it will be a stationary object. I highly recommend learning to hand launch and recover, there is often a lack of a large flat spot to land on and the boat may be pitching.

Having crashed my Mavic Pro a year ago trying to launch from a moving barge on the Danube, I can tell you that this is a very worthwhile skill to develop but I would wait if you are a relatively new pilot and don’t have a lot of practice. Carrier pilots have to be very skilled before they attempt their first landing. This is not nearly as hard but it is a very unforgiving environment for mistakes.

 

[nealh]

Hi I'm planning an outing on a friend's 50 foot aluminium boat - plenty of steel as well no doubt. I expect I'll be able to lock into ~10 - 15 satellites but not sure about compass calibration. If I have clear viability; no wind etc am I going to be able to operate without risk of rogue flyaway etc - I'm not for example wether the controller will allow me to fly if steel upsets the compass? Thanks

The boat may have a lot of electronic interference.
Be careful, also take off and land from the part of the boat where the wind is blowing away from the boat.
I had a lot of trouble on a 28’ foot boat.

 

[drvrbob]

I fly off of my 18ft basstracker all the time. I dont recalibrate compass. I place the drone on its case take off, hover about 10 ft above boat check that I have good satellites,home point recorded fly around then hand catch. No problems.

 

[hoggdoc]

Hi I'm planning an outing on a friend's 50 foot aluminium boat - plenty of steel as well no doubt. I expect I'll be able to lock into ~10 - 15 satellites but not sure about compass calibration. If I have clear viability; no wind etc am I going to be able to operate without risk of rogue flyaway etc - I'm not for example wether the controller will allow me to fly if steel upsets the compass? Thanks

Say goodbye to you investment. Not the best plan.... It's never a good plan to fly over water if you can avoid it.

 

[UPTGrad]

> ... but not sure about compass calibration.

Hi. Not often mentioned, but launching from a moving and rocking vehicle never allows the IMU to calibrate.
Raising it to hand launch also affects the IMU, as your arm is never steady.
Modern jet aircraft require a few minutes for the IMU's to calibrate, and if the aircraft is moved ever so slightly, the whole process has to be restarted. I would "assume" the same general principal applies here.

 

[Flynz]

G

In Atti mode the drone does not use GPS for position holding.
The compass is still used.

Good luck with that. Very hard to fly. There will be a breeze and you could be all over the place. Not recommended.

 

[Flynz]

Hey why not wander down to the jettty put the drone on the front deck away from the engine and turn it on. If the magnetic interference signals comes on and stays on maybe stick to hand held photography. If it does not do a little hover at a meter and see what happens. The boat needs to be stationary when you take off and land. On Instagram Drone10 (I think) has videos on boat hand captures. Always two people.