GL: Hyper Mileing - Twin Engines

[Jim Fidler]

We completed the Loop in 2004 in a 36 Mainship equipped with FloScans
and ran on one engine (or the other, alternating days) most of the time.

The boat had Borg Warner Velvet Drive transmissions which completely
safe to freewheel.

The FloScans proved to be very accurate.  Careful measurements in
no current, no wind conditions consistently showed better than 25%
difference in fuel consumption at or below hull speeds when one engine
is shut down.

I doubt the results would be the same for all boats, but it is certainly
worth a try compared to other "hyper mileing" techniques.

I believe that both engines benefit from this practice.  The
engine that's not running is not wearing out and the engine that is running
benefits from the increased load, so long as the RPM is kept at a safe 
level.

Total engine hours required to complete the Loop are just over half of what
it would take using both engines all the time.

Regarding the drag created by a free wheeling prop there is competent
advice available.  In Dave Gerr's Propeller Handbook he says there will be
less drag when the prop is free to rotate.

Jim Fidler "Fiddlesticks"