Who has a ZF BW7 transmission?

[prroots]

To a transmission mechanic a wet-plate clutch transmission isn't a "hydraulic transmission", but to an old all-gear transmission user it is, it uses an oil-bathed clutch surface that I refer to as hydraulic. There are wet clutches with slip-friction surfaces, designed to slip, all through the drive train. And wet plates don't like a prop in gear, rotating the clutches. Maine Sail says you can lock down your ZF in reverse and not damage the plates. I don't understand how that works. I run a Kanzaki wet plate transmission and it MUST be parked in neutral, or you will destroy the plates. I would ask ZF how placing their transmission in reverse "locks" the transmission. It may be that the PO was an old-timer who thought it was fine to park the transmission in forward (not reverse). Or the boat was a charter...

Prior to your posting, everyone agreed that the shaft could be locked while sailing (engine off). The only controversy was whether the ZF model BW-7 should be locked in Forward or Reverse gear. No one has suggested that locking the shaft will damage the transmission provided the recommended gear is selected.

As an aside, I have received a private message from a user of the identical transmission also attached to a Westerbeke engine. He reports that the shaft intermittently rotates when the transmission is placed in Forward gear. He also reports that the shaft is locked when Reverse is selected. Once discovered, he has always placed the gear in Reverse while sailing. He has done this for over 10 years and many 1000's of miles without problems. To me this is very strong evidence that Reverse is the correct gear to lock shaft safely despite what Westerbeke (and their manual) states. As stated above, this agrees with my experienced transmission shop, the local Westerbeke dealer, and the manufacturer, ZF.
Pete

 

[prroots]

Yesterday, we launched our boat and had our first opportunity to test the transmission. The shaft spun freely while sailing in neutral (engine off). The shaft locked while the gear was in both Forward and Reverse.

We have sent another email to Joe Joyce of Westerbeke (attaching the email and attachment received from ZF) asking for his opinion; he failed to respond to the previous two. If anyone has influence with him we could use your help. It seems that resolving this contradiction would benefit all so we're at a loss why Westerbeke won't take this issue seriously.
Pete