Prop shaft difficult to turn by hand

[SimonA]

My engine revs seem to be about 800 (in gear) below what other people say they get with the same boat and engine (BMC1.5 with 1:1 gearbox). I noticed I can't freely turn my prop shaft by hand, it takes a lot of effort to turn and is very stiff. Someone said if my stern gland was too tight it would get hot with the engine running in gear. It does not even start to get warm.

I'm stuck as to where to look next. Could it be the cutless bearings? Or maybe the rope cutter?

 

[dickh]

Is the shaft alignment correct? I had a a BMC 1.5 with a 1:1 g/box in a Moody 33 and the shaft easily turned. Have your rubber engine mountings collapsed? Mine had when I removed the engine for replacement, as well as being soaked in diesel and were not working correctly.
Try undoing the bolts on the shaft coupling, split the coupling and see if it turns then(and you can also check the alignment.
Incidently when fitting the new engine I found that the cutless bearing was not in line with the stern gland, but to rectify it I would have had to remove and refit the 'P' bracket(difficult!) and decided that I would just renew the cutless bearing more frequently. Done 2 years with 150hrs on the engine and still OK. Good Luck anyway.
My BMC 1.5 would not rev above 1600 with low idling speed of about 750 RPM.

 

[SimonA]

Thanks for that. The alignment could be out, one of the engine mounts looks like it's in need or replacing and the engine does vibrate around a fair amount when in gear.

I'm getting 1800 RPM giving about 4.5 knots. Other owners of the same boat are getting 2500 to 2600RPM and about 6.5 knots.