Okay, I've read most of the posts about props, and don't seem to find the answer to my question about them.
Background:
Boat: 1994 Scarab Sprint, 18' The boat weighs 1348 actual with full fuel and one person aboard.
Engine: 160HP Mercruiser 4 cylinger I/O
Current Prop: 13 1/4 Diameter, 19 Pitch Stainless Steel, 3 blade.
Current WOT RPM is 5200
Current top speed is 41 MPH on GPS
Mercruiser"s recommended redline for this motor is 4800 RPM.
I believe, based on what I've read here and some other places, that I can lower the WOT RPM's by about 400 RPM by increasing the pitch to 21 while keeping the same diameter. That would put the WOT RPM and recommended redline in synch, while at the same time increasing my top speed. (If this is incorrect, somebody please tell me!)
I have available to me a 13 1/4 diameter, 21 pitch stainless prop, which I believe will achieve what I described above. However, it is a 5 bladed prop rather than a 3 bladed prop.
My question is this:
What will be the effect of a 5 bladed prop versus a 3 bladed prop? Does an increase in the number of blades affect the RPM drop for increased pitch?
I have been told (by people who I have no real confidence know of what they speak) everything from "no difference" to "it will cause some added stern lift", which if correct, should help the boat get on plane a bit quicker, right?
Thanks for any help you can give me... I've learned a lot here.
Background:
Boat: 1994 Scarab Sprint, 18' The boat weighs 1348 actual with full fuel and one person aboard.
Engine: 160HP Mercruiser 4 cylinger I/O
Current Prop: 13 1/4 Diameter, 19 Pitch Stainless Steel, 3 blade.
Current WOT RPM is 5200
Current top speed is 41 MPH on GPS
Mercruiser"s recommended redline for this motor is 4800 RPM.
I believe, based on what I've read here and some other places, that I can lower the WOT RPM's by about 400 RPM by increasing the pitch to 21 while keeping the same diameter. That would put the WOT RPM and recommended redline in synch, while at the same time increasing my top speed. (If this is incorrect, somebody please tell me!)
I have available to me a 13 1/4 diameter, 21 pitch stainless prop, which I believe will achieve what I described above. However, it is a 5 bladed prop rather than a 3 bladed prop.
My question is this:
What will be the effect of a 5 bladed prop versus a 3 bladed prop? Does an increase in the number of blades affect the RPM drop for increased pitch?
I have been told (by people who I have no real confidence know of what they speak) everything from "no difference" to "it will cause some added stern lift", which if correct, should help the boat get on plane a bit quicker, right?
Thanks for any help you can give me... I've learned a lot here.