I am part of the organizing comittee for a regatta in the Caribbean. There are locations with no practical anchoring options at which we would like to set marks.
Am I wasting my time or is this vaguely possible? If viable, is anyone here willing to hazard a guess as to what kind of budget might be needed?
Actually getting the bits built. assembled and programmed would be a whole other discussion. 
I think this can easily be achieved. One unknown is the mark itself - are you planning a big inflatable mark thatās need to combat the wind?
A quick look around this site (4 thrusters, 4 escs, battery, charger) you are at $1214 plus delivery.
You would need a some sort of floating pontoon and a water proof box.
With electronics, you are probably at $1500 to $1800 all up
You could do the āraspberry pi / pix hawkā or āraspberry pi / navio2ā option plus gps.
However for a fraction of the price possibly an option might be a bulk standard drone setup with flight controller and 4-in-1 esc. The gps (and a FPV camera!) would just hook Into the flight controller. You would be able to remotely confirm the mark was in position or move it in a wind shift. You would also have remote control or flight planning where the depending on distance, the mark took itself out to the point and came back when finished 
. You could also have remote FPV camera and barometric pressure. Could be a very smart and capable markā¦
Complete setups with FC, ESC, camera, video transmitter frame, gps are under $140. You would also need a remote control. Just an ideaā¦
Interesting.
I suspect that I understand just enough about this to avoid asking profoundly stupid questions but am still far out of my depth here. I would likely hand this off to someone more capable than myself to develop.
Your cost estimate is well within our budget. I was considering just using a large diameter tube sealed and weighted with the batteries serving as a keel. It would be buoyant and have less windage than the traditional inflatable markers. Self-righting and somewhat collision-proof.
Your second option would then be an ariel platform or would this also be able to control a floating mark?
Thanks for the feedback!
The idea for the drone was to still have it floating controlling thrusters, but allow it to manage the need to stay in one place.
There would be no flying component. It also has some handy built in features like remote telemetry (to confirm you are where you want to be) and remote camera.
I understand what you mean.
I imagine that there isnāt much difference between differential lift and differential thrust. The price advantage is worth some investigation.
Thanks again!
I think this is totally achievable with readily available components like @deepsouth points out. Iāve been waiting for someone to pop up and try it!
How long does the marker need to be āactiveā before you can change the battery? About what size does it need to be?
Iām imagining that around eight hours would be sufficient. I rather like the idea of a vertical tube that provides both buoyancy and visibility. Impossible to capsize and most likely to survive the inevitable ācollisionsā that come with aggressive mark rounding. Perhaps a eight inch PVC tube would be all thatās needed? Two thrusters could provide both steering and mobility I would think.
With more capacity, self-deployment and recovery would be an awesome feature.