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shaft generators on yachts

Discussion in 'Technical Discussion' started by balboa, Dec 30, 2007.

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  1. balboa, Dec 30, 2007
    #1
    balboa

    balboa Guest

    I've been looking to find manufacturers of shaft generators but it seems most of them (I was only able to located Siemens and SAM Electronics) are geared towards big merchant marine vessels where the idea is to take advantage of the savings generated by heavy fuel oil powered main engines.

    In our conversion project, we have a MGO powered diesel engine but it has a lot of spare power compared to what we need to cruise so, a shaft generator would mainly serve to limit running the regular generators and take advantage of a engine that's running anyway.

    We'd be looking at something in the 100-200 KW range. Our main engine is a 9 cyl. Deutz 628. Max. 2000 HP at 800 rpm but we cruise at about 600 RPM.

    Any suggestions or comments are welcome.

    Thorwald Westmaas
  2. K1W1, Dec 31, 2007
    #2
    K1W1

    K1W1 Senior Member

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    Hi,

    Whilst this is a good idea it can be far from simple to implement in a one off scenario.

    How you are going to drive the Alternator ( I am assuming it's AC Power you are after here) is important. The speed of the input is critical, so you will have to work out the ratio between your shaft speed and the required speed of the Alternator to get that right.

    You might be able to fit a hydraulic pump to the front of that engine and drive the alternator that way.
  3. TSI AV, Dec 31, 2007
    #3
    TSI AV

    TSI AV Senior Member

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    Hi,

    Good idea, of course.

    It's not a problem to find an AC generator. STAMFORD, PILLER, TAYO..., you name it.

    But...

    1. How are going to make a PTO solution ? As K1W1 mentioned, it can be done hydraulically. I doubt, that reduction gear has a "spare, free shaft" to do this mechanically. With this solution probably an oil cooler will be needed.
    2. You will have to choose a generator, which has some important identical characteristics to existing generators in order to do seamless switching without voltage / current hunting.
    3. You will need some extra space (or another panel) on Your switchboard to install main breaker and some other stuff involved.
    4. Equlizing connections / contactors will be needed.
    5. Probably main engine's governor has to be adjusted for a "generator mode" (droop, compensation) when running at required rpm.

    However, it's all can be solved. I think, the question is only abt money (as always), :D

    Petty, that Your yacht is not equipped with CPP, otherwise You could run on shaft generator even at different loads of main engine.

    Please keep us updated about Your project, it's intriquing.

    Good luck and best regards,

    Andrei
  4. K1W1, Dec 31, 2007
    #4
    K1W1

    K1W1 Senior Member

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    Hi,

    Andrei,

    If it was CPP Equipped was my first thought then looked at the Avtar and saw a fixed wheel so didn't bother to write about CPP setup.

    The biggest problems I see are as you mention with the governor setup and the control of the output itself if shaft speed is not constant (or very close to it). There are Voltage Regulators that can compensate for this but these are not cheap by any means.

    Depending upon his gearbox he may have a PTO which can be utilised. An ex Trawler may also already have a substantial hydraulic system or the remains of one that can be adapted to serve this purpose. If it is being setup from scratch then as you rightly say an oil cooler either using existing S.W for the Main Engine/Gearbox or with a dedicated pump will need to be included in the system.
  5. balboa, Feb 1, 2008
    #5
    balboa

    balboa Guest

    Thanks for all your feedback guys. I've spoken with some yard and companies selling the equipment. Bottom line: it's at least 2-3x as expensive as adding a regular generator and the efficiency has also some limitations.

    Since both main engine and generator engines use MGO, there's no cost saving like when you run your main engine on heavy fuel.

    So, we'll just ditch that idea. But, this whole brainstorming session led us to keep one of the existing generators and simply replace the AC and DC generators with one big AC generator.

    Now, I'm looking at stabilizer solutions :)

    Slowly but surely this puzzle is coming together.

    Thorwald
  6. Seafarer, Jul 7, 2008
    #6
    Seafarer

    Seafarer Senior Member

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    Something seen on The Discovery Channel's "Deadliest Catch" - http://www.gentechglobal.com/

    Instead of a direct PTO, it's a PTO driven hydraulic pump with a hydraulic generator drive motor, and the engine-driven pump is controlled for flow and pressure for constant power.

    Does this make sense? Thoughts?
  7. Electrospot, Jul 10, 2008
    #7
    Electrospot

    Electrospot New Member

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    Hello balbao, i was suprised to see your vessel on the website. this ex- beamtrawler seems to be very familar to me. If I'm not wrong this must be the ex UK-43, Deo Volente. This means that you will have one diesel with an ac and a dc gen in line i When you want to generate more power, it is maybe an idea to replace the dc-gen for an extra ac-gen, or replace both dc and ac for one big ac. What about the switchboard, will it be replaced or do you leave it like this.
    Another possibility is to use the dc power tfor driving an ac gen, but that will means lose of power. Is your bowthruster still dc or will it be ac?
    What do you mean by stabilizers, for your electric power or stabilizers for your vessel

    Anyway good luck, Electrospot