Bravo III increasing from 26 to 28 pitch

rock doc

Petty Officer 1st Class
Joined
May 29, 2011
Messages
241
Our Maxum 2300 in under propped with a set 26P props. It has a 2000 7.4l mpi motor and we are hitting the rev limiter (4650 rpm) with 5 audults on board and a full tank of gas at 48-49 mph on GPS. I plan to swap for a set or 28P props this week. Seems to be lots of conflicting information on whether a high gear ratio turning a higher pitch prop slower is quicker then an equivalent theoretical setup with lower gear ratio with a lower pitch. Most of the information I found is for race boats, which indicates that turning a higher pitch is quicker. Any thoughts on whether is this true for a BIII paired to a 4500 lb cuddy like ours? Also, do I risk putting too much stain on the lower end of the drive with this setup? I believe someone replaced the original outdrive with a much lower 2.0 gear ratio before I bought this boat used - just hoping this is something that can be straightened out with a simple prop change.
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
40,712
Your slip is in the 14% range with current setup, would like to know what the speed is with the drive flat and even with the hull. Suggest finding the gauge reading when the drive is flat and even with the keel. Then take it for another run and see where your at

Should be in the prop section
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
12,961
The 2000 7.4 WOT range is only 4200 - 4400 rpm?
Spinning a high pitch prop at a lower rpm, is slightly more efficient than spinning a lower pitch prop at a higher rpm(less energy tied up in spinning it faster). Blade tip speed is lower and slightly less prone to cavitation. Props in a given line tend to also be slightly more efficient as pitch goes up
 

QBhoy

Fleet Admiral
Joined
Mar 10, 2016
Messages
8,308
Are you sure of the rev limiter at those revs ? Surprisingly low, if so.
 
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