ZF Marine debuts new propulsion concept for inboards

MattP

ZF Marine today introduced the “Project Disruption” concept at the Fort Lauderdale International Boat Show. The new propulsion package is the first contra-rotating system for inboards with traditional shaft-drive systems.

The concept lets inboard-boat builders take advantage of contra-rotating propellers; the most obvious advantage is improved efficiency. The concept takes a standard ZF Marine transmission and utilizes a strut-housed underwater gearbox to transmit power to the twin propellers. Initially, the concept was designed for water-sports towboats and ZF said it can be scaled to larger boats.

“For many years, there has been little innovation in inboard shaftline technology,” Keith Stanley, pleasure craft product line manager for ZF Marine, said in a statement. “ZF saw the opportunity to bring all the benefits of contra-rotating propellers to this most traditional of propulsion systems. We started with tow sports because it presented a unique opportunity to investigate the concept at full scale while subjecting it to a wide variation of loading conditions.”

In addition to increasing efficiency and acceleration, ZF said the concept will give boatbuilders the chance to consider a wider range of transmission ratios than what is possible with single-prop applications. It should give naval architects the ability to optimize the propeller-to-gear ratio.

Lastly, the contra-rotating propellers will address one of the biggest shortcomings of single-prop inboards — poor performance when backing up. They will eliminate the propeller torque, which basically only lets a boat back up in one direction.

ZF Marine debuts new propulsion concept for inboards

RazorRoss3

But what effect does it have on my spray around the ball?

liquid d

What? so now I won't be able to make fun of MC drivers when they get in my CC? What fun is that?

oldjeep

So it is like a Bravo duoprop I/O. Neat concept, hate to think what the props will cost. Looking at the props, sizewise they actually look like bravo props and the bottom of an I/O outdrive

MISkier

I wonder if the additional underwater gear (strut mounted gearbox, etc.) and/or any change in churn of the water by the combined props will negatively affect wake characteristics.

thager

Like boats don't already cost enough? Let's throw even more parts into the mix. Seems pretty unnecessary to me.......

Beeker

@thager I could not agree with you more..$$$$

Jody_Seal

@thager,
Could not agree more. Overkill for a simple application. getting closer to the $100K ski boat as it is. I can see something like this on a lake tanker, however pod drive technology is fast becoming reality in smaller pleasure boats. Also this duo drive shaft unit is really nothing new. The Arnson surface drive is very similar however it is mounted on the transom rather then through the bottom of the boat.

Viva La Revolution

Wish

Boats feel diff already with diff manufactures to prop options to engine size options when it comes to ZO. So now more veriable options would be available to manufacturers?

oldjeep

I think the application is surf boats, not ski boats. Counter rotating props would take care of the issue where the surf waves are not as good on one side. The pictures are of v-drives, not DD's

DW

I recall the Ski Pro Twister was fitted with the Volvo Duo Prop, had a top speed of 70 mph. IIRC not a stellar slalom wake. Agree not needed or probably wanted for a 3 event boat but time will tell.

Jordan

Hmmm....looks like an unneccessary complication. I also wonder if it will be a disadvantage to lose the directional bias of the single prop. I use that to my advantage when docking. While this set up will undoubtaedly go straight when backing up, it not turn any better when there isn't and current from the props washing over the rudder.

Keith Menard

My daytime job is motorcoaches. ZF came in with catepellar a bunch of years ago and was going to REVOLUTIONIZE the motorcoach industry. You literally can't give those buses away now.

Beeker

@Jody_Seal IMO no prop torque while driving a course would be kinda like tracking a hwy in a car with some loose steering.

bigskieridaho

Dumb. Keep that stuff on I/O boats. Not even needed on V drives either. If it isn’t broke don’t fix it right?

Dacon62

Wow...nobody has even tried or driven a direct drive with this tech and all this poopooing.
It may be awesome or it may be a flop but let’s give it a chance. Hey it’s something new (potentially) for us direct drive guys. When’s the last time that happened!?

Jordan

Simple is better.....this isn't simple.

UWSkier

My first thought was what @jordan said. Duoprop setups work well when the thrust direction is controlled by the helm. Unless there's a sprag clutch on the forward prop or something, the reverse "pull" that is ingrained in my being will be gone.

eleeski

Working on this?!

Eric

oldjeep

@eleeski - mastercraft already made a twin engine wakeboat. X-80

A_B

I would be more interested in an electric motor. Plug and Play!

eleeski

@A_B Two electric motors in a hybrid? With the right controllers the boat path and time could always be perfect. The human driver could watch Harry Potter videos (bad reference to a Tesla problem).

@oldjeep Just one engine needed.

DW

IIRC the electric CC had twin electric drives (actually one case with 2 rotors) with belts to 1 prop shaft.

oldjeep

@eleeski that looks like a reliability nightmare, not to mention all the parasitic loss.

lpskier

Don’t get a rope in the prop(s).

eleeski

@oldjeep Compared to a counter rotating prop?

I wonder if a single electric motor driving the prop where the energy comes from a motor/generator might be more efficient. It adds an interesting possibility to reposition the generator for wake adjustments. Run the engine back for tricks and wakeboarding and forward for slalom. Another project?

Eric