CS prop
Maine Sail,
I am considering replacing my MW 17x10 2-blade with a Campbell Sailor and I came across this thread from 2009 and I am hoping to benefit a bit from your experience.
Are you still using your CS and have you been as pleased with it as you were when you wrote the post?
I am concerned about the size of the prop they have proposed (15x8 3-blade) because I would like to avoid having to change it as it seems others, including yourself, have had to do.
My boat is a Niagara 35, as you know, with specifications not too different than your CS. It has a Westerbeke 42b4 and a Hurth HBW-150V-2R (2.13:1).
The 17x10 2-blade does fine, enough power and gets me up to the 3,600 rpm, however, even though the running gear is in good condition and properly aligned, there is still some vibration and I typically cruise at 2,000-2,200 even though Westerbeke recommends 2,500 rpm minimum. Even though I don't have much vibration now, I am still hoping to eliminate most of it with a 3-blade.
You had your prop adjusted to 16x9 and reduced the cupping as well. I don't know how different that would be than the 15x8 they are recommending. Even though our boats and drivetrain are somewhat different, particularly your 3,000 max rpm, I would appreciate your thoughts about their recommendation.
Thanks,
Rob
After much research and consternation I decided on a new prop this past winter.
After consulting with Norm at West By North, the makers of the Campbell Sailor. I ordered a 16"X10X1" RH prop.
The CS prop is EXTREMELY efficient. Norm spec'd mine at 16" diameter X a 10 pitch. I was skeptical at first because my three blade Michigan Wheel was a 16" X 12 pitch which is a lot more aggressive. I could not understand how, with loosing so much surface area, I could also reduce pitch? Norm used the Michigan Wheel prop size calculator, which he tweaks for the CS prop design, and decided on the 16X10. Unfortunately when I got the 16X10 it was still over propped and I was under max rated RPM by about 300 RPM. Not good.. Over propping your engine is never a good idea so I wanted to fix this as soon as possible.
Once I discovered the 16X10 was still to aggressive, despite the blade surface area being MUCH smaller than the Michigan Wheel, I called Norm. Norm decided to drop the pitch to a 9 and remove some of the cupping on the trailing edge of the CS props blade. Norm's rational was 1" of pitch for a 200 +/- reduction in RPM then some reduced cupping for another 50 +/- RPM. Again this is not an exact science.
The customer service Norm provides is stellar! He actually sent me a brand new replacement prop ahead of time so I could literally change out my prop, with the boat still in the slings, and then send the used 16X10 prop back. The 16X9 prop worked flawlessly and I am now within 30-50 RPM of max rated with a clean bottom and prop.
