Wakeboarding - June 01, 2018

Whether it’s a tournament tow

boat or a Downeaster, boats

powered by single inboard en-

gines require more technique

and skill to operate in the close

quarters of a dock, marina or

launch ramp than boats pow-

ered by other sources.

Enter Project Disruption

from ZF Marine’s (zf.com)

Special Driveline Technology

unit. Introduced as a concept

last fall, sources say that Proj-

ect Disruption testing and

development are currently un-

derway aboard an undisclosed

make of test boat at an undis-

closed location. For now, this

is what you need to know about

this new propulsion system.

Project Disruption inter-

faces with a standard-issue ZF

Marine transmission and is

comprised of a strut-housed

underwater gear box that

transmits power to two contra-

rotating propellers.

“For many years there has

been little innovation in in-

board shaftline technology. ZF

saw the opportunity to bring all

the benefi ts of contra-rotating

propellers to this most tradi-

tional of propulsion systems.

We started with tow sports

because it presented a unique

opportunity to investigate the

concept at full scale while sub-

jecting it to a wide variation of

loading conditions,” says Keith

Stanley, product line manager

for Pleasurecraft.

Know that Project Dis-

ruption addresses more than

just maneuverability. Its twin

contra-rotating propellers de-

liver more blade area without

an increase in overall diame-

ter. That can result in superior

acceleration and the ability to

hold plane at a lower speed and

provides more options with re-

spect to optimizing the torque

and power characteristics of a

marine engine for the mission

of the boat it’s intended to be

installed aboard. Because prop

diameter is limited, the means

to deliver optimized power and

thrust to the water have been

limited too. But the increased

blade area of contra-rotating

props gives propulsion engi-

neers a way to more precisely

harness a marine engine’s out-

put for the desired perform-

ance characteristic.

Since docking is a hot topic

for most boaters, we’ll consid-

er the potential slow-speed

maneuverability gains boaters

might expect from Project Dis-

ruption in detail.

An inboard-powered boat

lacks the directional thrust

of steerable drivelines, like

outboards, sterndrives, wa-

ter jets and pods. Instead of

a steerable prop or nozzle,

they rely on defl ection of the

propeller stream by a rudder.

Compounding things, when in

reverse, there is no stream of

water from the prop fl owing

over the rudder at all. This

couples with a propeller’s ten-

dency to induce a sideways

PHOTOS: COURTESY ZF MARINE

ZF PROJECT

DISRUPTION

A new driveline in development by ZF Marine

seeks to overcome some challenges inherent to

inboard propulsion.

ZF

WATERSPORTS

TRANSMISSIONS

The performance requirements

to move boats with 10,000

pounds of ballast have demand-

ed higher-horsepower engines

that produce driveline loads

previously never seen. The ZF

48IV and 68IV transmissions

were designed for such duty. For

more information, visit zf.com.

74 | BOATINGMAG.COM | JUNE 2018