Join Date: May 2012
Location: North Vancouver, BC
Thanked 44 Times in 41 Posts
Rep Power: 8
Re: Flexofold prop performance
Just to be clear, the standard is that you reach max rated rpm at wide open throttle, while underway. Not just that it matches the old prop, which could have theoretically been wrong. Sounds like you're likely in good shape though.
I'm afraid I have to call something amiss with a 39ft boat (estimate 35 LWL) making 9.7kts over the water. Hull speed would be approx 8 kts. You'd have to be incredibly over powered, not just an efficient prop. Was that speed over ground, assisted by current, perhaps?
I am going to do further testing to verify, but unless something changed in the calibration of my knot meter in the 2 weeks the boat was out of the water, it has always been accurate. Unfortunately I was fighting an ebb tide my whole trip so wasn't able to verify with the GPS. Speed over ground was over 1-2kts slower, until I got out of the current in the Cove where the boat lives. Once I got out of the current the knot meter and gps agreed with in .2kts, but at that point I had to slow down to 5kts.
The max rated engine speed for my engine is 3300rpm, and on my boat wide open throttle is just over 3200 with both props.
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2011 Jeanneau 39i Azura