prop testing need input

J

jcassjr

Cadet
Joined
Sep 5, 2009
Messages
23
i have 1989 maxum open bow the boat info is
20' ,130 hp 3.0L ,30 gal gas tank, i do have hydrafoil, the lower end is
mercruiser aipha one drive the test i did was 18p-14.5 4-blade 4600 rpm@32 mph the other prop was a 3 blade 17p-15.5 @5000rpm 35 mph prop are alum.
the 3-blade had better hole shot 6 sec. to on plane ware the 4 blade was 10 sec. looking for a driving across the lake prop with 4 pepole in boat. the boat rpm range is 4200 rpm to 4600 rpm
 
Last edited:
hwsiii

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: prop testing need input

I don't quite understand what is going on with your props, because usually a 4 blade prop has less prop slip than another aluminum 3 blade prop. My assumption is that the 4 blade prop has very small blade surface areas and the 3 blade must have a very large blade surface area and/or has a lot of cup built in to the prop. But neither one of them has a low enough prop slip to get good speed out of your boat, you should be down to about 9% prop slip at WOT for maximum speed at any RPM on your boat.


H
 
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