The most common and most likely answer to this crossword clue is the 5 letter word YACHT
I've seen this crossword clue in The Guardian
Y
A
C
H
T
More clues leading to the result YACHT
- Turning turtle roughly in your old boat
- Yen to join German eight in fast boat
- Unusually achy time in sailing boat
- Unknown eight in German vessel on water
- Craft initially handled roughly in river capsized
- Vessel unknown, number spoken by U-boat crew?
- Safety ultimately caps number in German craft . . . .
- Leaders of yesteryear approach captain helming tourist vessel
- It makes sail going about the cay, having left Spain
- Luxury purchase set back your old checking account
Buddy explains!

The straight part
We know that "vessel" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case vessel = yacht.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does YACHT mean?
YACHT noun- A slick and light ship for making pleasure trips or racing on water, having sails but often motor-powered. At times used as a residence offshore on a dock.
- Any vessel used for private, noncommercial purposes.
- To sail, voyage, or race in a yacht.