Alpha one prop.Help neede!

[ccustomrides]

Hello guys,
I need help with a prop situation. I have a 1990 4.3 Mercruiser with a alpha one gen 1 drive. Boat is a sea ray 200cc so a 21ft cuddy. Anyway when I first got the boat it would run 40 mph with a 21p alluminum @ 4600 or so RPM WOT. This winter I upgraded to a Stiletto 21p stainless. Now it runs 44 mph and RPM @ WOT is 41-4300 depends on conditions. My question is this. Will switching to 19 p stainless help my WOT and bring my top end seed up or will it stay the same. It is quicker out the hole with stainless and I can trim it way out and it still holds bite unlike allumin from before. Also does switching from alluminum to stainless drop rpm even if ou stay in same pitch?Thanks.

 

[usskydvr]

Re: Alpha one prop.Help neede!

Depends on the model of 19' you go with. In general you will get your RPM up 300-400 and but lose 2-3 MPH. The 19 will be quicker still out of the hole.
As for switch from Al to SS with the same pitch. Again the model comes into play as I have NEVER seem the EXACT model prop in both AL and SS. Even if you found one, the SS blade are generally thinner, so they would have less drag and more RPM, but offsetting that is that they wouldn't flex at all thus taking more power and thus turning less RPM. ( No simple answers when it comes to comparing AL to SS)