I have owned the hella "boat fan" (not the turbo), on the last boat. I hated running them because of the noise. They stood up well though.
Would definitely look for something quieter this time.
Another option is to use computer case fans
They are cheap ($2-20), there are a million types and they all run on 12v so you just hook them up to a switch and go. Better still since silent and low power draw computers are all the rage they always list their cubic foot per minute flow rate, their db sound rating and amp draw. They are available from 1.5"-6" or larger. Not all look the same either. This one is 8" diameter "silent" and $22:
Or this 14inch monster, which moves 129CFM silently(22db) drawing 500ma
Google "computer case fan" or try PC Case Fans and Cooling Fans at Xoxide.com - Computer Case Fans