Using nRF52840 to send data over open sea surface

[Harry94]

I am currently working on a project where I try to send data from a swimmer in the open sea to a point on the land (beach). I know that Bluetooth communications are blocked by the water, but would it be possible to achieve this communication whenever the wrist of the swimmer (wearable) is out of the sea? Will the sea environment allow this communication?

[Harry94]

Edvin

Well, there are two scenarios based on the range. If the the range can reach the shore then yes, it would be a phone. Otherwise, I could connect to an Arduino enclosed in a buoy in the open sea, and then with an antenna communicate with the phone on the shore.

awneil

How could I detect it then? Do you have something more efficient and long range in your mind?

Thank you both for the replies.

-Harry

[Edvin]

Harry94 said:

Well, there are two scenarios based on the range. If the the range can reach the shore then yes, it would be a phone. Otherwise, I could connect to an Arduino enclosed in a buoy in the open sea, and then with an antenna communicate with the phone on the shore.

 Well. This is all possible, but you would simply have to test in the conditions that the device will operate in to see whether it will be detected or not. As awneil says, maybe a beacon would be more suitable, instead of actually connecting to the device. 

[awneil]

Edvin said:

maybe a beacon would be more suitable

But, as already noted, it'll need fast advertising - which will draw a lot of power.

And, if the device is only above the water briefly, it may not be enough for a scanner to "catch" (beacons are usually assumed to be "permanently" visible)