space savers in some boats and can make it
possible to fit more accommodations in the
boat. The drawback to all V drives is that the
additional gearing creates somewhat more
power loss, and access to the stuffing box un-
der the engine and behind the UV drive can
be difficult and must be carefully considered
during design.
Remote-mount V drive
The engine is installed facing backward and
(usually) angled slightly down at the forward
end. A jackshaft connects to the engine drive-
shaft and runs into the aft end of the V drive
mounted some distance forward in the boat.
The jackshaft is usually fitted with CV or uni-
versal joints at either end. (Figure 16-3 shows
a remote-mount V drive.) Like the UV drive,
the V drive changes output direction to
reverse and runs aft and down at an angle.
Angles are usually between 10 and 15
degrees. Remote V drives allow great flexi-
bility in locating the engine. They do lose
more power to gear friction than other
drives. The remote V drive has its own inde-
pendent lubrication system.
Chapter 3: Transmission Geometry, CV Joints, Stuffing Boxes, and Engine Mounts and Beds
Figure 3-1.
Transmissions
compared
(Courtesy ZF
Marine)Unusual gears
There are gears with the output shaft offset
to the side rather than down, and gears with
outputs angled down and offset to the side.
There are specialized gears that allow two
side-by-side engines to drive one shaft, and
gears that allow two engines (one in front of
the gear and one aft) to drive the same shaft.
Such gears are usually installed on craft with
gas turbine engines. Gas turbines burn so
much fuel that their vessels often fit diesels on
one side of the gear and the gas turbine on the
other. The diesel is termed the “loiter”
engine, used for low to moderate speeds. The
gas turbine is used for high-speed pursuit
operation. All these unusual gears are intended
for special design problems that don’t apply
to the vast majority of ordinary craft.
Regardless of the gear geometry you
need, you must check with the manufacturer
to confirm that the gear will mate with the
bell housing on the engine (except for
remote V drive); that the gear is rated for the
engine’s maximum torque, horsepower, and
rpm; and that the gear will fit in the hull. It’s