Re: Close call! Who had rights?
You may be describing a situation where you're drifting in neutral (or engine off) and other boat was doing the same?
I don't think the crossing, meeting, overtaking, or "who's on whose starboard side" applies here, since neither of you, though "underway", had a "course", which the rules envision. Both drifting (into each other)? I'd call it a "special circumstance" where fault isn't assigned under the rules, you both may fall under Rule 2, the "special circumstances" rule, where you just do the best you can under the circumstances. No hard and fast rule, I don't think.