What???? Are you serious???
You can't use something 'just because it works'... ESPECIALLY if it costs a fraction of the proper "Marine" device! Shame on you! You are required to save your pennies, pay exhorbitant prices for that 'proper, approved' marine gear..
Sorry, couldn't resist!
Actually, good on you for improvising but really, in this case the adjustability won't be as slick and some of the parts may corrode rather quickly... though any vang is better than no vang at all, as long as it's adequately strong..