The Fenix lights I have seem to have a "dazzle" effect rather than a "strobe": the duty cycle is not far from 1:1. A true strobe would be more like 100:1 or more, especially if battery run-time is important.

It's worth noting that these people had fish nibbling on their clothes as well as who-knows-what other distractions. It seems like anything that floats by itself it pretty important: survivors might remember to turn the light off during the daytime but otherwise I wouldn't plan on this piece of gear getting much more attention than that - it falls in the category of gear that needs to do the right thing without any help from an operator.