Thanks for the input. It is providing quite a bit of food for thought.
I understand that this is not necessarily a black and white question. I
have had the unfortunate experience of a total vessel loss once before
and know first hand how hard any insurance company will look to avoid
paying a claim, hence the question. Fortuntately for me that time it
was a material failure and was documented by an investigator. Still
this was an unfortunate experience and not one I wish to relive!

So the problem rests with the company reimbursing my fuel expense. What
about the case where I and a few fellow employees go out for the day
and they contribute fuel money? Is that a boat for hire situation?
Another case is someone we do business with and I go out for an
afternoon for lunch... I expense the lunch and the fuel cost. This is
not intended as a charter... I still set the agenda and go where and
when I specify, not the guest. How can this be construed as a charter?
Another question revolves around me, as a manager, taking my team out
for a day... expense the fuel and I am not covered. If I pay for the
fuel... and we discuss business (hard not to) am I now covered or not.