Single engine, dual independent props for cat?

Relative newbie here, so please be kind.

Does anyone know of, or can envision, a single engine driving two independent props, including the ability for counter forward/reverse? Can this be done via separately controlled transmission gear boxes between the motor and each prop?

The application would be in a larger power multihulls. The advantage seems to me to be less expense (one diesel vs. two), though I do not know what the transmissions would cost, nor how and where the linkage between engine and the drives would look like.

Just dreaming…

 

Where are you going to keep the engine?

port hull; then you'd need to run a power takeoff up and across the aft cockpit and more transmission down to the cutlass for the starboard prop

Too many things to fail.

 

I think that system like what you propose would be better suited to a sailing catamaran with 2 small auxiliary propulsion units.
I remember seeing one with a system like this once, but I can't remember what make of cat it was.
Nowadays you could maybe look at two electric motors being driven by the diesel engine?
However for a larger power cat, I think you would be much better off re safety and redundancy if you have two diesels.

 

Yes, I was actually thinking about a single diesel-electric powering the two independent props through the gear boxes, so it would be one diesel and one electric engine powering the two props, with the diesel only being used when the battery banks are depleted. One question is would this be a better set-up than one diesel generator, plus an electric motor in each hull.

My application is for inland water use, so I am not too worried about redundancy.

 

No. Gearboxes is out. It could be done hydraulically I suppose, but not sure it os sensible.

You would be way ahead with either a diesel engine in one hull and electric engine in the other or a diesel generator and two electrics. Boatbuilderfl is building an electric boat with tesla batteries and the engines actually have regen units on the forward edge. Somehow they calculated a lot of 'free' power was available.

The reason for this is the other way has too many power trains. For a monohull, it could be done, but a multihull, no.

As to which is better; the diesel/electric or the generator/dual electric engines; all over again, more moving parts in the latter.

I have a feeling the diesel and electric combination actually will be a thing with the electric side even including regen.

Depending upon horsepower needs; as long as you can find enough power; something like a torqeedo and a small diesel engine may even be possible versus an electric inboard which carries more cost.

This generator and two electric engine solution would have the hurdle of where to place the generator. It would be loud and demand air.

 

That’s helpful. Thanks.

 

I found this electric outboard system, currently in testing. Too much power for my needs, but a good point for consideration.

Evoy launches the world's most powerful electric outboard motor https://newatlas.com/marine/evoy-most-powerful-electric-outboard-motor/

 

Hydraulic propulsion - Power hydraulics https://www.vetus.com/en/power-hydraulics/hydraulic-propulsion.html?limit=32
Vetus hydraulic drive, it would be reasonably easy to use a larger pump, larger heat exchanger and add another motor and shaft

 

I ‘ve not heard of this technology. How well does it work, and how does it compare to other propulsion systems? Is there any reason why the pump could not be powered by an electric motor? If so, what would be the advantage over straight electric motor to prop?

thanks

 

A "modern" electric drive system will be more efficient than hydraulics and not have the problems of hydraulic leaks and similar.

How is the power distributed to the prop on each hull? Using mechanical shafts with angle changing gearboxes will probably be expensive and likely to have alignment and maintenance problems.

A single engine-generator with a motor at each prop is likely to be the most efficient, most reliable and probably lowest cost. Add batteries if operation without the engine running is desired.

 

I agree. Thanks.

 

What do you all thinks of this single diesel, two prop system proposed by Hybrid Marine, U.K.:

 

I checked it out and looks really smart. My only question is about the weight. You'd have to be real thoughtful about it.

 

If you or anyone else is interested, I will post the specs and partial price sheet that I requested from the company.

 

Yes please, that would be nice.