View Full Version : Atomic 4 (Bristol 32) Prop
Robert Brand
12-16-2005, 11:16 pm
I have an Atomic 4 30 hp direct drive on a Bristol 32 (1969) and considering a two or three blade prop to bring me to 2,000 rpms. Presently have two blade 13" 8 pitch, with 1,400 rpms max. In the past had a three blade 13" 8 pitch bringing it to 900 rpms. Any suggestions regarding size and pitch to achieve the 2,000 rpms? Thanks.
Talk with these folks. They specialize in A-4's. Your RPM seem to be on the low side. Might be a problem other than prop. Brian http://www.moyermarine.com/
13x7 rh 3/4 inch shaft prop that was on the Atomic four that I took out of Bietzpadlin when I repowered. That would be a thelve and a half reduction in pitch which would increase your RPM a bit. I used it for a while with my new engine and a 3:1 reduction gear but it was not adequate to push 30 feet and 41/2 tons so I went to a three blade. I can check on "BoatDiesel" and see if their calculator shows anything interesting.