Quote:
Originally Posted by vgomezp
I have seen it takes her more than usual to plane, and after planning she is able to gain up to 38 MPH. Which is more than enough for me. However planning faster for me is a must.
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What is 'usual'?
You should start with a baseline.
1) Moderate load (1/2 fuel, 1/2 water, limited people, and gear)
2) A fairly calm day with relatively calm water.
Get the boat up on plane with the drive(s) and tabs trimmed out properly. (Tabs should be out until just before prop cavitation).
The Maximum RPM range will be between 4400-4800. Ideally, you want to be as close to 4800 without going over.
If you're over 4800 RPM, you are under-propped (Pitch is too low).
If you're under 4400 RPM, you are over-propped (Pitch is too high).
Typically prop diameter is sized to be able to swing the blades with a specific range of clearance between the blade tip and the anti-ventilation plate. Props are therefore tuned by changing the pitch. In recent years, adding blades has been done as well.
Decreasing Pitch will increase max RPM's and holeshot (Time To Plane)
Increasing Pitch will decrease max RPM and holeshot
1" Pitch = 200 RPM (roughly)
Adding blades is similar to Increasing Pitch. (I'd suggest you avoid modifying both pitch and blade count at the same time).
The concept behind overpropping is a misguided impression that being able to maintain a higher speed while operating at a lower RPM leads to better fuel economy. While it may be true in the short term, the increased time to plane eats up a decent portion of that savings. The amount of increased load on the engine is more problematic. There are those that theorize that the increased load can potentially shorten engine life.
The following information is also helpful
Engine:
Engine HP:
Outdrive:
Outdrive Gear Ratio:
LOA:
Beam:
Weight:
Mercruiser Prop Calculator:
https://www.mercurymarine.com/en/us/...or/#!/step-one
2500 Plane Faster
Linear Mode
