Hi Leonard, Thanks for the response. It seems the 1 engine operation provides a 2.2% improvement in your example (2.45 nm/gal vs 2.40 nm/gal). Any thoughts on engine ware from the temperature cycling? Vince In a message dated 12/18/2004 9:39:51 A.M. Pacific Standard Time, PRINTMORE1 writes: Hi Vince: Good questions. Normal operation with 2 engines at 1600 rpm. average speed 7.5kts. fuel usage 3.12gph Single engine operation. 1700-1750rpm. average speed 6.5kts. fuel 2.65gph. helm adjustment 5-7 degrees. The unused shaft is NOT locked. BW trannies can operate in this mode at these rpms.(emphasized in their manual.) Remember we are only in this mode for 6hrs. We did experiment during our training trials on locking the shaft but quickly came to the conclusion that this was a dangerous procedure in case you forgot to unlock it. The KISS principle works very well. Hope this answers your questions. Regards. Leonard Stern, Indifference