ZF/Hurth - Switching Output Rotation

[jcollins]

Very informative repost from member Robb

I was in LA on business this week on business and stopped by Seaboard Marine and had a long discussion with Tony Athens (moderator at BoatDiesel.com) about Albin 28 and its engine systems design challenges. Mostly we talked about exhaust system design as my new Recon Cummins motor already has evidence of water in the turbo at only 50 hours- more on this in a separate post soon.

Anyway, we started discussing the boat wholistically- the bottom condition, prop, running gear, loading and while doing this there just happened to be a locked up HSW 800 V1 on the shop floor where we were standing that I commented on. He asked if I really liked running the left handed prop. I commented that I was used to it and did like it because that was my only option. Then he recommended that I change to a right hand prop because that is the "A" position for the Hurth gear. Albin set the unit up specifically for a LH prop by setting the gear up in the "B" position per Tony. This LH set-up essentially runs the gear in reverse by using the 4th (reversing) gear in the transmission. His general take is that running through 4 gears in the "B" position provides another failure point and causes some minor additional frictional losses, versus the RH "A" setting the only requires 3 on the internal gears engaged. As an added bonus, if the switch was made to RH I would be using the other clutch pack as my primary (that had previously only been engaged for reverse) and it should be in almost new condition. My Hurth gear now has over 3000hrs on it. All that has to be done to make this change is to change the position of the gear ship cables at the helm.

All this is possible because this V drive was designed for 100% power in either direction. If fact, he said that when the clutches are slipping on some boats that have this gear, he will have them change from a RH to a LH prop to engage the other clutch pack and keep them running for another few years before having to rebuild the gear.

I'm not sure if I'm going to change the but this is nice to know it can be easily done and possibly keep a boat running to finish a season if a problem does arise.

I just thought that this was something interesting to share.

Robb Stilnovich
"Stella Maris" 1996 28TE #279
Cummins 6BTA-370
Tacoma, WA