The most common and most likely answer to this crossword clue is the 5 letter word PRAHU
P
R
A
H
U
Buddy explains!

The straight part
We know that "boat" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case boat = prahu.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 PRAHU mean?
PRAHU noun- A sailing vessel found in the waters of Micronesia and Indonesia; it has a single, large outrigger and a triangular sail.