Upvote:1
No, there is no amount of time you have to be out of the US before re-entering. You can go directly from your arriving aircraft to US preclearance if you wish (and you have booked a flight).
Though it's not clear why you want to do this at all. If you're traveling to or from an aircraft or ship in conjunction with your crewmember visa, you could just go directly there (if the ship departs before the end of your existing admission).