Is a puzzlement….

[Bycrick]

THE BOAT: Norseman 447. Built 1982. Repowered in 1998 with Yanmar 4JH2TE, keeping and rebuilding the original Velvet drive transmission and V-drive. All ran fine since then.

A year ago, at the haulout, I discovered a "crack" in the cast/welded SS shaft strut. Over the years, I’ve read in forums about this problem. Found someone who could replace the strut.

To make a long story short, everything was replaced: coupling, shaft, shaft tube, strut, cut-less bearing. Only the MaxProp and the stuffing box fitting were retained.

PROBLEM DESCRIPTION: Engine starts and runs fine. Easily makes full RPM in neutral. Put it in either forward or reverse, and the RPM won’t increase above idle. If you disconnect the shaft coupling, it revs up fine.

That seems to indicate a shaft/prop problem, but we’ve checked the prop settings twice, and all seems good. No smoke from exhaust. Prop shaft seems a little hard to turn by hand, but that doesn’t seem enough drag to keep a 60HP motor from turning.

Any ideas?

[skipperpete]

Re consider the possibility that the prop settings are still incorrect and physically measure the blade angle in both forward and reverse. The maxprop booklet lists the blade angle to pitch relationship and its a useful way to quickly check the pitch. Often if the pitch is out enough to keep the revs near idle there is a marked increase in prop walk sometimes to the point where its almost impossible to get out of the slip.
If the shaft is tight enough to hold rpm at idle in gear then something will be getting hot, check the stern gland temp repeatedly over a 5 minute period with a laser thermometer and maybe check the gearbox too.

[Bycrick]

Pete — They settings on the prop WERE wrong the first time. That’s why I’m reasonably sure that they’re correct now. The original manual from the factory says the angle of 20* results in a 12.4 inch pitch. The blades have the same pitch and it seems close to 20*.

Ran the engine in gear at idle and the stuffing box didn’t get hot. But it doesn’t leak either even when the compression (front) part is completely loosened. That’s tomorrow's check as the saga continues. Thanks.

[JPA Cate]

I'm thinking it may be the cutless bearing. If you can inject some water or grease into it, you'd be able to eliminate or confirm it as a possibility, and proceed with that knowledge.

Ann

[jeanathon]

Sounds like the Yanmar is not making power. This could be anything from clogged fuel filter, fuel pump, etc.

[skipperpete]

Originally Posted by Bycrick

Pete — They settings on the prop WERE wrong the first time. That’s why I’m reasonably sure that they’re correct now. The original manual from the factory says the angle of 20* results in a 12.4 inch pitch. The blades have the same pitch and it seems close to 20*.

Ran the engine in gear at idle and the stuffing box didn’t get hot. But it doesn’t leak either even when the compression (front) part is completely loosened. That’s tomorrow's check as the saga continues. Thanks.

Did you have to move the engine off the beds to replace the sterntube? Have you tried operating the throttle and gear selector with the cables off ? ...against the dock lines?
I’m hesitant to keep on about the prop but I’ve become familiar with lost settings and how to restore them on maxprops. In one overly casual assembly of the marks by a contractor we achieved a spectacular 11.5 knots at 950 rpm with a 6-354 perkins and spent a large part of the night hauling out and resetting the prop.
What is the direction of rotation of your propeller viewed from the stern? Is the diameter 18” and what’s the reduction ratio.