Southeast Financial was the best when I was in the market, but my old school dealer who does everything on paper (doesn't even take cards for service) was just too much of a pain in the ass to work with to close through Southeast. I financed through my dealer and it was slightly higher.
Looks like they're still really competitive at 4.09%
https://www.sefinancial.com/boats/
'21 Moomba Max