Diesel/Electric Propulsion System Design - Have your say!

Discussion in 'Hybrid' started by CatBuilder, Sep 11, 2011.

  1. keysdisease
    Joined: Mar 2006
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    keysdisease Senior Member

    The Prout Snowgoose Cats had a retractable drive leg like a sterndrive that was center mounted on the nacelle. The post by dialdan reminded me of them, I think the drive leg may heve been a sonic.

    Steve
     

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  2. masalai
    Joined: Oct 2007
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    masalai masalai

  3. masalai
    Joined: Oct 2007
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    Location: cruising, Australia

    masalai masalai

    For the electric motors, (11kg light!! for the big - most power) to D135 specification draws 400=A at 90=VDC, so some HUGE loads and thick, (expensive-tinned-special), cables necessitating short runs to batteries or power supply... At least 30 KVA supply from the genset at 90VDC if you can find one such beast... or 240VAC to near engines then large rectifier and choke to smooth the current for manipulation by the electric engine controllers...

    Potential for massive RF noise depending on technology and sensitivity of nav and other electronics :eek: - - always seems to be problems - - ... Someone else can pay for the trial and error, "first cab off the rank"...

    SONIC CATAMARAN DRIVE MK I1
    The drive leg looks OK but what is this 15KG/MTR or for longer legs, 10Kg/MTR... What does that mean - is that sufficient what else delivers similar torque? unfamiliar territory there for me... Weight is acceptable at 50 to 60 kg (I assume for the different leg lengths 800mm to 1.2M) also the engine gearbox unit looks like it could be separated from the out-drive leg by using supported shafts with CV joints at either end to allow the engines to be moved further forward, for better weight distribution, but that may put noise and smell in the middle of the cat... :eek: again
     
  4. CatBuilder

    CatBuilder Previous Member

    That's why I'm looking at ac motors at 240 (208 3 phase). Tiny cables.

    Controller is called a variable frequency drive, but can't find one with morse control style handles.
     
  5. masalai
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    masalai masalai

    Try the computer-flight-sim equipment if the controllers just need potentiometers...
     
  6. pdwiley
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    pdwiley Senior Member

    You generally only need a 10k Ohm pot to speed-control them. Some of my Danfoss units run a RS485 bus control and you can control them from a computer.

    I kind of remember why I went cool on the idea now. Too many points of potential failure & weight/bulk.

    With a diesel engine & mechanical g/box if it gets totally flooded you change the oil, bleed the injectors if necessary and you're good to go.

    With a gen set you need to do the above plus dry the gen set, try to keep the VFD dry (IP66 rated unit maybe) and ditto the electric drive motor. If the 'magic smoke' leaks out of any 1 of the generator head, VFD or drive motor you're screwed.

    Weight/bulk: a generator head is at least as bulky/heavy as a mechanical drive g/box. In addition a 10kW electric motor is going to be approx 600 to 750mm long, maybe 400mm dia and mass over 40 kg. That's going off of the 7.5HP unit on my big lathe.

    I still think the concept is quite viable though. My Danfoss VFD units are in nice heavy cast aluminium housings with screw-on terminal covers. Not sure their IP rating but quite high I think. A TEFC electric motor will tolerate a lot of abuse in harsh environments, not sure about surviving immersion.

    Anyway, things to consider in the design process.

    PDW
     
  7. Brian@BNE
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    Brian@BNE Senior Member

  8. masalai
    Joined: Oct 2007
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    masalai masalai

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  9. michael pierzga
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    michael pierzga Senior Member

    The reason I ask is that duty cycle and service life are important when you spec gear or designing systems for a charter boat. Zero downtime is the goal. I also operate yachts industrially. Most years half season. . On this program the typical half year duty cycle is full time operation, all systems in action, from May 1 to Nov 1. Typically 13,000 miles on the log...500 hrs on the main engine , 750 hrs on the gen., 500 mainsail hoists, 500 tender launch recovery cycles, thousands of hydraulic winch actions, 35 kilometers of anchor chain hoist and deploy, thousands of toilet flushes.........................AC chiller units !!!!! shiver me timbers.

    I see the gear deteriorate and crumble before my eyes. The gear that crumbles first are the...NICE IDEA...non standard installations.

    Something as simple as the anchor handling gear. This boat has a non standard system. Windlass below deck, chain fed thru an underdeck pipe and stored in a chain locker three meters aft of the stem. Nice idea...clean deck for guests to use, chain mass aft out of the ends... BUT....its very high maintenance, short service life. To leed the chain underdeck requires a series of rollers hidden from view. Chain rollers are designed to guide the "+" profile of the chain. Chain is prone to forming a twist...with more than one roller this twist get trapped between the rollers in an " X" form . If not corrected this X form will destroy the roller and disable the system in a week. The picture is a week or two of damage.

    Check out the non standard chainplate installation in the background..very high maintenance, but it looks good and is guest friendly.

    When I hear you discuss non standard systems like Diesel Electric I say nice intellectual exercise, it may work perfectly, but ...Beware....the service life may be to short. Only choose true commercial grade equipment and use conventional commercial installation practices..

    Specifically ask the supplier of gear like a diesel generator what its service life is. If the high energy density Fisher Panda generator man says 20,000 hrs....submit him to a lie detector test before purchase..
     

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  10. masalai
    Joined: Oct 2007
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    masalai masalai

    Does that have something to do with batteries and electrodes? :eek: - - What a testi/specta-cular idea...
     
  11. Landlubber
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    Landlubber Senior Member

    John Gross....sorry typo...
     
  12. keysdisease
    Joined: Mar 2006
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    keysdisease Senior Member

    Re the "clean no drag" propulsion problem, what about a jet drive? I seem to remember a sailboat with a jet drive that was very clean underwater, small intake even smaller jet. Not talking the typical steerable bolt to the transom unit but a system that would exhaust straight aft underwater.

    There is a company that is marketing a thruster setup along the same lines. It involves a beltdriven pump bolted to the propulsion engine, a remote operated valve to direct thrust port or starboard, and "nozzles" that look like (and may be) standard thru hull fittings.

    Maybe something like a PWC jet drive driven by a small diesel (or hybrid electric motor,) may have to gear it up to get the right RPM's for the jet, just plumb the intake and exhaust how you want for an almost clean bottom. You could even exhaust the jet on the transom above the water for an even cleaner bottom if you wanted.

    Reverse would be a problem.:rolleyes:

    Just thinking out loud.:eek:

    Steve
     
  13. CatBuilder

    CatBuilder Previous Member

    Will respond more after work (fairing). MP: Yes, industrial quality is the only thing I will use. Genset on either electric or standard outboard setup would be a 1200-1500 rpm Kubota diesel. No high speed aluminum block junk. Your point is well taken.

    My other choice is a pair of t50 Yamaha high thrust outboards and a smaller generator to run large house loads and charge a large battery bank. Nearly the same setup, just smaller gen and outboard motors instead of electric.

    I have to wonder... what is more reliable? Inboard electric motor or outboard motor with fuel injection?

    Tough call. Anyone want to weigh in on that?
     
  14. CatBuilder

    CatBuilder Previous Member

    What brand of pod drive is Gideon using on those Fast Cats? Those seem to be working just fine and not leaking.
     

  15. michael pierzga
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    michael pierzga Senior Member

    I see outboard motors...good ones like a honda 50...operate 2000hrs without major problems. The defect with outboards is that they are one trick ponies. They can only turn a propeller. They cant generate electricity, they cant make hot water, they cant power a hydraulic pump or bilge pump, they cant power a refrigeration compressor......
     
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