If your engine is running whether ingaged or not, you are a power vessel due to the fact that you could and can slip it into gear very easily. And if you are motor sailing, I.E. with sails up and under power. You can't take it out of gear at the last minute and claim that you are a sail boat and have/had the Right of Way...
Ever though some people have tried that excuse.
Not true. The rules are clear about this.
The regs are written to prevent accidents. The intent is not to have people twist the rules to fit their needs. Unfortunately too many "floating Lawyers" read a bit and try to interpret how to gain advantage. In the sample of someone switching in and out of gear that skipper would be an ultimate idiot and wouldn't have support of the law.
I went through this "engine running" crap on a different site a few years back and eventually contacted the Coast Guard. Here is their reply:
Thank you for contacting th eUnited States Coasy Guard Navigation Center. In regards to your question Rule 3 Rule 3: General Definitions
of the Navigation Rules (International - Inland), COMDTINST M16672.2D defines the following:
* Sailing Vessel: any vessel under sail provided that propelling machinery, if fitted, is not being used (e.g. not propelling the vessel).
* Power-Driven Vessel: any vessel propelled by machinery (regardless of whether the machinery is in use or not).
It depends on which means is ACTUALLY propelling the vessel. We hope this addresses your inquiry. In our continuing efforts to provide service to the public, please inform us if this answer was helpful.
USCG Navigation Center
Navigation Information Service
7323 Telegraph Rd.
Alexandria, VA 22315
Website: U.S. Coast Guard Navigation Center
Hope this clears it up. Also unfortunate is that several so-called training sites claim the opposite.