Additional electric motor while leaving original in place and using original ax

Hello there All ,
I want to leave my original caterpillars in place and beside of the axes I want to mount electrical motors . The idea is to use the existing axes and somehow gripping the these axes .
Is there somebody who did this or can help me realize this conversion?
Thank you and kind regards Patrick

 

Hi Patrick, do you mean the cats are disengaged from the prop shafts, or you want to leave the cats engaged, and augment their power with electrics, or put the cats in neutral and power the shafts only with electrics ? With unlimited money anything is possible, it can be done, but why. If you got the right type of electric motors, they could become generators when driven by the cats. Do you have a large battery to supply these electric motors? Please give us more details.

 

hi Seasquirt , the idea is to put the cats in neutral, and with some kind of clamp to grip the axes, the cats will stay in place . I have 30kw batteries connected to a solar panel system . In another yacht I had I had such a clamp to activate a hydraulic pump ....it's a long time ago and don't remember how it was done .....

 

How much power do the diesels have? 30 KW are equivalent to 40HP so they may move the boat slowly for an hour.

 

Thank you Gonzo for your reply, the cats have each 155 kw ....but you don't go on full power... additional to the solar and batteries I have a generator which gives 17kw somehow this must move the yacht...

 

Abtrac and wessmar make a get home hydraulic drive that I'm guessing could be adapted to electric from the hydraulic setup. Drawing a blank but another company in b.c. Canada made an inline system like the abtrac that fit between the gear and shaft that could take another input like electric, seems like most new systems are gear integrated.

 

Thank you for your idea , I'll look at this if this might be what I'm looking for Comfisherman

 

It all depends on the desired power and available space.

Option one: pulley on the main shaft, pulley with clutch on the electric motor, toothed belt between the two. As seen for example here: Heat Exchanger Hybrid Propulsion - Beta Marine Propulsion Engines https://betamarine.co.uk/he-hybrid-propulsion/
Typical problems are space for the appropriate size pulley and shaft stabilization against flexing.

Option two: additional special gearbox. Basically the above but ready made with the power transmission either as a capsulated chain or as a right angle (or Z) drive with shafts. Usually mounted between engine and existing gearbox.

Option three: twin input marine gearbox. Basically option two but all in a single housing, it replaces the existing unit.

Examples of option 2 and 3 made in Italy: Hybrid - Transfluid https://www.transfluid.eu/en/product-category/hybrid/

 

Kobelt was the one I was thinking of.

 

Thank You Rumars for your reply, I have space enough to ad/build in the motor room and also above the cats ....as I have a 17 kw generator and the 30kw batteries something can be done to sail each day especially as I am in the Adriatic - Ionian sea where is mostly sun . If there's a day we cannot sail no problem ,I'm retired so time enough .
Concerning flexing as the axes from the gearbox to the first roller bearing ( let's name it ) bed is only about 25 cm I think this would be no problem , further to the flange where the ax comes into the motor room another 60 cm and then the ax is going through another 3 bearing - fixing tubes water-cooled ....so vibration is excluded due to the many fixing points.

Comfisherman what where you thinking about with the Kobelt?

Thank you Guys!

 

Get-Home Drives https://www.kobelt.com/products/get-home-drives/list/get-home-drives

Would think this would be adaptable to an electric as opposed to hydraulic. Use a Rockford sae b or c adapter to a Spicer type drive and you could long couple or offset an electric motor.

 

The propellers are matched to the diesel’s output, which may be quite different than what an electric drive motor needs.
A separate shaft with a folding propeller may prove to be more efficient and less complex than combining the two.

 

I'm not fully versed in sizing the torque of electic, but couldn't one use an inline reducer to get the ratio correct for slow speed?

 

If you need to run the generator, it is unlikely to be more economical that running one engine at low speed.

 

The output specs of the diesel and the electric motors must be very similar to drive the same propeller.
There’s much more to the propeller spec equation than just the reduction ratio.
A variable pitch propeller might get you in the ballpark?
Or two speed transmissions are a possibility, probably less drag than a secondary reduction gear would be.