Not the person you're asking, but I sail a 7 ton, 10 metre yacht. I can change course by 90 degrees in under 10 seconds if I need to (probably far less, depends how hard of a crash tack I do).

people do need to sleep if they're soloing offshore, so the warning would need to be at least a minute to be able to wake up, then there's putting on the safety equipment to go out on deck etc. So make that multiple minutes of warning for it to be useful..

Im not aware (which is not to say it doesn't happen) of that many incidents with sailing vessels and whales. However, you've prompted me to look, and it's more than I thought.

https://www.yachtingworld.com/cruising/new-approach-to-reduc...