T&T: M/V use?

[Jerry Berndt]

Ok, here is a newby question...

I can make a guess as to what the M/V that precedes some vessels  
names stands for.. is it Motor Vessel ?

But when is it appropriate, or what is the protocol to use the term?

Does a 12' dink w/ an out board qualify? or is that frowned upon?

Is it appropriate for a 32' bayliner with 2, 90Hp diesels?

etc

PS, Thanks for all the helpful comments on IR thermometers, lots of  
experience here...