Martin Baxter wrote:

Well, the wind is coming over the other rail, so the vessel
is now on a different tack; ergo the vessel has tacked.

A more accurate way to say it is 'the vessel has been tacked.' Happens
all the time on smaller lakes with flukey winds. Sometimes two boats
going bow to bow will be on the same tack.... more of a probelm if
they're both on starboard...

Fresh Breezes- Doug King