as the drone completed the first half circle a gust of wind hit it and the next thing i knew it was heading slowly for the water
Your best bet of finding out the reasons for the descent is to post the flight log
What drone are you flying, what controller are you using and if relevant what phone are you using ?
I have no idea about these automated flight plans but the only reason I can think of for wind causing a drone to descend is that the programming, at that particular time, prioritised either holding position or maintaining the flight path, over maintaining the drone's height.
I have a vague recollection of such a thread where this was thought to be the case when. The flight was I think somewhere over the Med and the drone was heading home into a strong headwind.
At height, over water, the drone's behaviour should be no different to its behaviour overland.
By anecdote height control over water only becomes of concern once the drone is low. I have had one instance of this and I probably have over a thousand flights over water at heights ranging from a few feet to possibly 300ft. This incident occurred at the end of a speed run and the water was probably quite shallow.
Roughly speaking the VPS thing of
@Zbip57 's video relates to situations where the VPS systen achieves a good lock on something on the ground or the surface of the water.
Where the VPS system does have such a "good lock" the drone's position holding system prioritises the data from the VPS system over the data from the GPS system.
Consequently if the something moves the drone follows it so as to 'hold position'.
I doubt this is applicable to your situation.
Over stationary ground the VPS system provides MUCH better position holding than does GPS. This is fairly easy to demonstrate.
In daylight, outdoors, on a relatively windless day and somewhere where you have good GPS with NO objects nearby, fly two flights.
In the first flight bring the drone down to, say, slightly above head height then let the drone hover for a minute or so. Take note of how much it moves around horizontally.
Land the drone, switch it off and mask the VPS sensors with a couple of layers of Gaffa/tank tape. Repeat the test, though you may not want to leave it hover for a minute or so.
In which flight does the drone move about more ?
