Make sure to check the integrity of your prop strut after you upgrade/fix your current prop and verify drivetrain alignment, good luck!
On Sun, Nov 10, 2024 at 8:40 PM ejwills1993--- via CnC-List < cnc-list@cnc-list.com> wrote: > Hey all - > > I have a 30 Mk II with the original Yanmar 2GM20F and factory Martec 15D x > 11P x 1 2-blade brass prop. About 850 hrs on the engine, seems in great > shape. > > Issue: I can only motor at 2200 RPM before the engine/stern begins to > vibrate. This puts me at a max cruising speed of 5 kts. > > From the survey, one of the prop tips measures about 1/8 inch farther AFT > (axially) when at 12 o’clock position versus when the other tip is rotated > to the same 12 o’clock position. The prop blades are not chopped/scraped > and the prop appears to be otherwise symmetrical in all other dimensions. > > The engine does not vibrate when revved to 2800-3000 rpm in neutral. > > The shaft does not wobble, and there is no leakage from the shaft packing. > > Q: What cruising speed should I expect from this boat and the Little > Yanmar? I think the spec in the Yanmar manual says cruising rpm should be > 2700-2800 rpm without breaking a sweat. I’m not expecting to motor at 8-9 > knots like a big sailboat but I do expect to be closer to the 30-footer > hull speed of around 6.7 kts. > > I’m trying to figure out if this is a valid excuse to get a folding prop :) > > Thanks! > > -Eddie W. >
