There is a french built system available that is based on detecting the conductivity in 2 pipes that go down through the bottom of each hull
. You can set it to release if the water
disaapears from one tube (maximum safety) or from both.
It releases a solenoid that opens and releases an intermediate 4:1 system in the sheet. This has strong bungy cord attached to soften the release.
Some of the early Catanas had this system as a standard option.
A have played around with some ideas as I work in process control, but I'm not keen on having 4 extra holes in the boat.
The option I'm looking at is the one that some of the ocean racing
tris use, some have headboard locks that can be manually released, others have a spinlock cam cleat at the top of the mast
above the headbord that also can manually be activated or released.
This system depowers the sail without risk of damaging the battens up against the stays. Just leave an appropriate amount of slack on the halyard
before fixing it at the bottom of the mast
. But this is not automatic, but could be made so using e.g. a small CO2 cylinder to drive a piston to pull the cord.