Prop Step Up

For technical tips, questions etc. on all subjects except Engines and Boilers.
User avatar
Full Steam Ahead
Full Steam Ahead
Posts: 899
Joined: Wed Nov 18, 2009 6:08 am
Boat Name: Otter, Rainbow
Location: Menlo Park, CA

Re: Prop Step Up

Post by barts » Thu Jan 17, 2019 2:57 am

TriangleTom wrote:
Wed Jan 16, 2019 10:34 am
barts wrote:
Tue Jan 15, 2019 4:17 am

Otter has the same problems w/ her 2.5" x 2.5" single as the counterweights are too small; the old 2" x 2.5" single acting twin was much smoother at speed, of course. I went to a 16"x20" prop from her old 13" x 17" because the new engine ran away w/ the small prop, but at full throttle (180 psi) the crosshead and big end bearings really hate me.

- Bart

I'm curious what you're doing for crosshead and big end lubrication that lets it stand up to that much pressure.
The slippers have oil cups and work fine, but the top bearing is bronze and hardened steel w/ grease and the big end (not big enough) is bronze w/ an iron crankshaft, with a rubber line and and 18" of head from a oiler. The bearings won't take the pressure, and wear quickly, which is why Otter doesn't participate in races and we cruise at perhaps 100 psi. A good thick lube oil has helped on the big end.

This engine is 100 years old, and I had to redo the top bearing when I got it as it was worn out, and the big end needed adjustment as well.

- Bart
Bart Smaalders Menlo Park, CA
Post Reply