With regards to putting a "the" in front of a vessel's name I think it's most common not to. But depending on the rest of the sentence structure, it may be more natural to include a "the," particularly if the sentence is being spoken, simply because it flows better.
We do not put a "the" in front of La Perouse in writing or speech. But some names lend themselves to a "the" better than others. "I'm going out on Nimitz" is probably the more "correct" sentence structure, but the easier to say and probably the more common structure is 'I'm going out on the Nimitz."
While I have not made any sort of study of this, it seems to me that vessel names that are made up of two or more words tend to be used without a "the" where single word names often tend to be used with a "the."
"The battle between the Monitor and the Merrimac." "Gertrude L. Thebaud almost won the International Fisherman's Race against the Bluenose."
So I don't know. There probably is a "rule" somewhere but I don't know what it is. So I just say and write what flows the best in the sentence.