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Diesel Electric Superyacht

Discussion in 'Technical Discussion' started by stavsantis, Nov 18, 2010.

  1. stavsantis

    stavsantis New Member

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    Hi, I am currently designing the powering/propulsion system of a superyacht as a project at university and I have run into numerous problems.

    1) The yacht will have 3 CAT gensets providing up to 5,500kw and a minimum of 1300kw. If the yacht requires only 850 kW when at anchor for hotel loads and stabilizers it would not be efficient to run 1 genset at 1300kW as power would be wasted. Would the best solution be to have a separate aux. generator?

    2)solar panels are also to be used as a renewable source of energy, can their power simply be added to the switchboard?

    3)Does anyone know of any simple calculations for hotel loads and fresh water stores per person/time at sea for superyachts?

    thanks!
  2. AMG

    AMG YF Moderator

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    Hi, if you are sure the yacht will need 850 kW at anchor, a 1300 kW genset is probably what you need. But I guess both figures should be lower and that you install 2 additional gensets with the right size.

    Solar panels can be added to the grid, but is a waste of space on such a power consuming yacht.

    On average consumption, I have no figures, it depends on climate and facilities onboard.
  3. stavsantis

    stavsantis New Member

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    others have told me that 600kW is alot however, from a paper written for modern superyachts it quoted a hotel load of 600kw for an 80m yacht....
  4. AMG

    AMG YF Moderator

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    OK, how big is your project yacht..?
  5. stavsantis

    stavsantis New Member

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    75m so i assumed it would be the same
  6. AMG

    AMG YF Moderator

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    I think you would be fine with two 500 kW gensets and a small emergency generator (fitted on the upper deck), besides what you need for the propulsion.
  7. Capt J

    Capt J Senior Member

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    First, you should design the yacht and calculate all of it's load sources such as air conditioners, ovens, refrigeration, then decide on generators. I would choose 2 generators, where 1 generator can run everything on the entire yacht. Then it's possible to get a 3rd generator that is 75% of the output of the other 2 and can be used during lighter load periods. I've found though, that it is rare that you're not pulling close to the same load all of the time, unless it's 70 degrees outside (PNW) and you're not running any air conditioning/heat
  8. K1W1

    K1W1 Senior Member

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    Hi,

    Did the Author have any real life experience of superyachts other than seeing them from the dock?

    You should make a list of all your electrical equipment as previously suggested and then get a load balance calculation done by a marine electrical engineer.

    Building an 80m Motoryacht that is going to cruise extensively with only 2 Main Gensets is short sighted at best. If you use main 3 Gensets you can have one out of action for maintenance etc and still have full functionality.

    I am doing an 80m boat now with 3 x 435 Ekw Gensets and a 120 Ekw Emergency Genset. It's sistership needs approx 280 Ekw when underway with the normal range of hotel services on offer and peaks up with the Galley. We need two sets on when manouvering as the thrusters can use nearly 600 between them at 100% capacity. The yacht was setup to run on one Genset most of the time and the first one has proven to do this and do it well, they have run 9000 hrs on the Gensets in 3.5 yrs and have no problems so far.
  9. AMG

    AMG YF Moderator

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    K1W1, what do you think of using some power from the main gensets of 5.500 kW as backup? Or would you not connect those to the "hotel side" at all?
  10. K1W1

    K1W1 Senior Member

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    Hi Lars,

    The main stumbling block to sharing the drive bus and hotel services bus is the formation of Harmonic Distortion on the AC Sine wave that comes back of the Freq Controllers used to operate the drives. A lot of DE Installs are higher voltage and 60 Hz which does not suit a lot of Hotel Equipment.

    If I were going to do it that way I would certainly look at the use of a Motor Genset driven by the Drives side of things and supplying the Hotel Services with Clean power. I have personal knowledge of one large DE Project where this has been done and it works very well according to the operational C/E and ETO.
  11. stavsantis

    stavsantis New Member

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    as far as my knowledge on superyachts, evidently it is almost non existent, this is part of a 3rd year university project i have been assigned. for propulsion power i have chosen 3x3516B CAT gensets coupled to 2 pods. I can see that using solar power will not provide much power however the yacht specifications is for it to be as 'green' as possible so using some may help.

    do you run the gensets for aux. power (hotel loads) 24hrs a day? or are they connected to batteries from which power can be used at lower loads?
    if so what sort of batteries are suitable?

    k1w1 - what voltages to you suggest i use for the hotel loads? 240v??

    I apoligise for my ignorance in the field and any help would be useful
  12. AMG

    AMG YF Moderator

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    If you must do a "green" yacht, forget about the thousands of kW and make something like this:

    Attached Files:

  13. K1W1

    K1W1 Senior Member

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    Hi,

    At least one of the Gensets will be running 24/7/365 unless you can get enough shore power or they are stopped for service/maintenance.

    Why have you particularly chosen 3516 Engines and what is the rating of the ones you have chosen?

    There is a very successful DE Yacht a bit bigger than what you are asking about that runs multiple smaller Gensets and two pods. The approx Power requirements are the same as your proposal.

    You should try and get as much of your Hotel load as possible - AC, Galley, Laundry, Sewage Plant, Water Makers etc on 3 Phase Power. The single phase consumers are not that much in total and the whole phase balancing action is a lot more straight forward of you don't have to much single phase stuff on the system.
  14. TheAdmiral

    TheAdmiral Guest

    As well, you can estimate 800-1200 Watts/room for A/C depending on temp differential and humidity. Radar systems/GPS and other Cockpit electronics are easily calculable. Another 300W - 400W per person is a good rule of thumb for 10 people or more which would include direct usage plus refrigeration etc.

    The big sporadic use systems such as Cranes/Pumps etc have to be estimated individually based on duty cycle.
    Last edited by a moderator: Nov 19, 2010
  15. Marmot

    Marmot Senior Member

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    Isn't anyone going to comment on this fundamental misconception?
  16. YachtForums

    YachtForums Publisher/Admin

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    Some of the world's greatest technological break-thrus started life as a sketch on a paper napkin, probably over a pint of ale at a local pub. And here we have another example... in just a few pencil strokes, Lars has penned the answer; vertical wind turbines and a bank of solar panels on a multi-hull.

    Attached Files:

  17. K1W1

    K1W1 Senior Member

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    Hi,

    Isn't that the truth.

    I have heard the MS DOS started as 12 lines of code on an Airline Napkin during a flight taking two Uni Students to a meeting.

    The rest is now history.
  18. Andrew B.

    Andrew B. New Member

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    Solar Sails ?

    Wondering if the idea of Solar Panel Sails has been explored ?


    A lot of great songs started as one line on a napkin, etc. Almost all great art stated as sketches on throw away paper ! Of course it's now delete, delete, delete. Rarely "save as is" !

    Let's make it a motor-sailor with Solar Panel Sails AMG and we got a winner...

    Sorry for the slight thread hi-jack....:)
  19. AMG

    AMG YF Moderator

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  20. Garry Hartshorn

    Garry Hartshorn Senior Member

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    In the mid 80s I was part of the deck crew on HMAS COOK which was a diesel electric oceanographic research vessel. As I was not an engineer at the time I maybe a little off on a few points. She was powered by 7 largish Cat generators 4 for propulsion and 3 for house and a silent running unit which from memory was a Lister mounted above the bridge. I believe that while the propulsion generators could not supply the house the house could supply or supplement the propulsion.

    It seems to me that one of the benefits of diesel electric is having many identical smaller engines and you only run what you need. To have only 3 generators to supply propulsion as well as house seems pointless. With the loss of energy between each transition, diesel to electric to electric motor through gear reduction, it would be more energy efficient to used a conventional drive.

    By the way the engines all had names Snow White being the lister and the 7 Dwarfs for the Cats

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