boat engine rotation

George Selby gselby4x4 at
Fri Mar 29 02:14:20 EST 2002

At 12:30 AM 3/29/02, you wrote:
>Actually, it's kind of funny, but most of the twin engined yachts that have
>counter-rotating engines are mostly for "local" use.  Many of the more
>serious world cruisers have two engines that rotate the same way.  This cuts
>down on the number of spare parts you needs to carry, not only from the
>perspective of spare parts, but also so that one engine can be cannibalized
>to service the other.

Well actually, whether or not the engine rotates backwards depends on the
type of drive used in the boat.  A boat with a straight driveshaft (inboard
power) will use a counter-rotating engine to get the prop to spin the other
direction.  An inboard/outboard drive (an outdrive or sterndrive i.e
Mercruiser or ovloV-atneP) uses accomplishes the rotation reversal in the
drive unit, so both engines spin the same direction, but the props spin in
opposite directions.  Outboard engines and props spin in opposite
directions in dual installations, thus are sold in matching pairs, LH and
RH rotation.

George Selby
83 Audi Coupe GT
gselby4x4 at

More information about the quattro mailing list