I’m wondering if someone out there can help us with a propeller pitch question.
We have a 34’ CHB here in Puget Sound that I’m pretty sure is propped wrong.
Our hull speed should be 7 knots to maybe a bit better but to get it, we have to push our poor old 120 Lehman to 2200 rpm which is way past its ideal operating RPM of 17-1800. Hence, we poke along at around 6.5 knots at 1900 RPM, wasting fuel as we go. We have a Paragon transmission with a 2/1 reduction.
Right now, our prop is a four blade 25L x 13.
I’ve spoken with our local prop shops and the concensus seems to be that we need to re-pitch it. It’s such a hassle to do that I’d like to get it right the first time. I guess each inch of pitch has the general effect of shifting RPMs by about 200 RPM.
Could anyone with a similar hull (34’ Grand Banks or CHB) let me know what they’ve found to be the ideal prop for this hull.