The most common and most likely answer to this crossword clue is the 9 letter word SPINNAKER
I've seen this crossword clue in The Times
S
P
I
N
N
A
K
E
R
More clues leading to the result SPINNAKER
- Tack into wind and run this sail
- A hook at the back splitting top sail
- Tack into wind, beginning to raise sail
- Regularly tack in top sail
- Wild prank in sea, not a feature of yachting?
- 27, perhaps, concealing a monarch’s sail
- Spirit blown over, filling topsail?
- Large sail secure in wind? Right
- Jack handles this type of bowler maintaining attack at both ends
- Small folded napkin put before the Queen. It is used before the main course
Buddy explains!

The straight part
We know that "this sail" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case this sail = spinnaker.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 SPINNAKER mean?
SPINNAKER noun- A supplemental sail to the mainsail, especially a triangular one, used on yachts for running before the wind.