How do you determine which size prop is optimal for your boat, engine, etc.? I've got a CD33 with a Universal 24hp model 5424.
rdtec@aol.com
Followup: How do I know what size prop to get?
Moderator: Jim Walsh
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M. R. Bober
Re: Followup: How do I know what size prop to get?
Very esoteric subject with lots of opinions. Our CD330 with Universal 24hp had a two blade 14 RH 10 Columbian prop when we bought her. We felt that we needed a bit more thrust and opted for a three blade prop (understanding that there would be an corresponding increase in drag which would slow us under sail).
The local prop shop uses a rule of thumb which called for dropping 2" (14 RH 8) of pitch to get a three blade prop of the same diameter as the two blade unit. When they realized that we had a "Columbian" ("heavy chord" they said), they felt that we could drop 1" (14 RH 9) and still be OK. Being OK meant that the engine would rev to within 100rpm of its max in neutral while in forward gear. We cannot. The shop will replace the prop in the fall with the 14 RH 8.
Find a local shop that specializes in props (they usually cater to power boaters) they should be willing to stand behind their recommendation.
Hope this helps
thebobers@erols.com
The local prop shop uses a rule of thumb which called for dropping 2" (14 RH 8) of pitch to get a three blade prop of the same diameter as the two blade unit. When they realized that we had a "Columbian" ("heavy chord" they said), they felt that we could drop 1" (14 RH 9) and still be OK. Being OK meant that the engine would rev to within 100rpm of its max in neutral while in forward gear. We cannot. The shop will replace the prop in the fall with the 14 RH 8.
Find a local shop that specializes in props (they usually cater to power boaters) they should be willing to stand behind their recommendation.
Hope this helps
thebobers@erols.com