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  1. #1

    How big of a Genset do I REALLY need? Your advice appreciated...

    Gents,

    I'm in the unenviable position of needing a new genset. Situation is I have a Norpro 21kw which is dead....and I could get another engine setup for it to cobble onto the still good generator, but I'm going to be in the $8k range for that, which is of course less than a replacement FOR THAT SIZE of genset, BUT for the same money, I could drop down to something way smaller, and go new. I am not convinced that I would have to give up that much because I have a whole boat inverter (outback 3232).

    So, looking at specs for like a 5.5kw Kubota Marine unit, it provides almost 42 running amps at 120V or half that, 21 amps at 240v. Maggie Mae has a LOAD of electrical stuff, but really, the only thing that I can't run off the inverter are the AC's, and that's with NO genset (main alternators charge inverter batteries underway)


    I note in the marina that everything on the boat plus one AC running is in that range of amperage pull, so maybe I could even run one AC on this little genset, which would honestly work for me, but it could also charge the batteries on the inverter which, outside the AC's is all I actually need to have happen.

    So, I don't want to trip over myself to save a couple of grand and have a way undersized genny which becomes a functional problem, but the idea of a small little 250 pound, easy to get in, quiet, fuel sipping kubota is awefully appealing.

    So, how big of a genset do I REALLY need?
    J R McCoy-100 Ton Master1980 53my-“Maggie Mae”Hull #576 Charleston, SC- Isle of Palms

  2. #2

    Re: How big of a Genset do I REALLY need? Your advice appreciated...

    At least 15k.
    1977 Hatteras 58' MY, Hull No. 304, 4-stateroom galley up model with 8V71TIs in Knoxville, Tennessee

  3. #3

    Re: How big of a Genset do I REALLY need? Your advice appreciated...

    I don’t know what your cooking situation is but if you have electric stove top and oven running with the water heater and the battery charger at full output you are probably pushing about 10 k right there, add an AC unit and you will be over 10 k. Unless you are really good at energy management like turning off the water heater until the battery charger ramps down etc. you will definitely require more than 5 k, min. Of 10k. John
    Mahalo V
    1974 53 Motoryacht
    Hull Number 406
    San Diego, Ca. Ready 32 Nordic Tug, Brunswick Ga.

  4. #4

    Re: How big of a Genset do I REALLY need? Your advice appreciated...

    I think you'll find answers to be a somewhat subjective.

    We had a Northern lights 16KW genset in our Hatt and without going into great detail in terms of what happened, that eight year old unit which was working perfectly prior to an unfortunate "incident" was replaced with a new NL 20kw unit a year and a half ago.

    The reason why we went up in size was because sister wanted to have the ability to run all the AC units all the time if/when necessary plus ancillaries. PO actually replaced the original 20KW unit (can't remember if it was Onan or Kohler but one of those two) with the smaller 16kw NL unit because he didn't think he needed as much capacity.

    On our Chris Craft we've got a 6.5kw Onan, however it's capacity is marginal in terms of being able to run both AC units and anything else. Genset is original and have looked at replacing with something larger if we decide to keep the boat.

    The other thing to keep in mind is resale value. We bought our Hatt because engine hours were relatively low, genset reasonably new and sized somewhat adequately. If you install a much smaller genset that may work against you if/when you try and sell.
    Brian L

    IMPETUOUS - 1984 Hatteras 53 ED MY Hull #CN720
    GOD'S GIFT - 1972 Chris Craft 42 Ft. Commander
    QUEEN B - 1974 Century 24 Ft Buccaneer
    GOD'S LITTLE GIFT - 1962 Johnson 19 Ft. Runabout
    MON AMI - 1984 Catalina 30Ft. Sloop

  5. #5

    Re: How big of a Genset do I REALLY need? Your advice appreciated...

    5K--no way. What was the NORPRO? One day you'll sell that boat. Think ahead.
    Semper Siesta
    Robert Clarkson
    ASLAN, 1983 55C #343
    Charleston, SC

  6. #6

    Re: How big of a Genset do I REALLY need? Your advice appreciated...

    Quote Originally Posted by racclarkson@gmail.com View Post
    5K--no way. What was the NORPRO? One day you'll sell that boat. Think ahead.

    The Norpro was a big old honking 21K. But Maggie Mae didn't have an inverter when it was installed...practically everything on the boat runs (while underway) on the inverter without any genset at all. Main alternators keep inverter bank charged.

    So, thought I could drop down in size, but the consistent advice on this subject is to go big or go home. Based on everything I'm reading, I'll go 15k or larger.
    J R McCoy-100 Ton Master1980 53my-“Maggie Mae”Hull #576 Charleston, SC- Isle of Palms

  7. #7

    Re: How big of a Genset do I REALLY need? Your advice appreciated...

    I got lucky and bought a boat with 2. 12.5 and 20kw. With family aboard the 12.5 can't keep up without me switching things off. . Uses 1/2 the fuel so great on delivery or with just the guys.
    As stated, less than 20kw is likely a discount when you sell.
    Mal
    Miss Molly
    '85 53ED #750

  8. #8

    Re: How big of a Genset do I REALLY need? Your advice appreciated...

    Quote Originally Posted by jrmccoy View Post
    The Norpro was a big old honking 21K. But Maggie Mae didn't have an inverter when it was installed...practically everything on the boat runs (while underway) on the inverter without any genset at all. Main alternators keep inverter bank charged.

    So, thought I could drop down in size, but the consistent advice on this subject is to go big or go home. Based on everything I'm reading, I'll go 15k or larger.
    Aslan can trip the dock (at multiple marinas) with not everything running. I could sell extra juice with all on with my NL20KW. I don't currently invert, but hard to imagine running much while also recharging on a small unit.

    I'll be passing you on Saturday about 1300 headed up to refuel in McClellanville. Listen for the long blast.
    Semper Siesta
    Robert Clarkson
    ASLAN, 1983 55C #343
    Charleston, SC

  9. #9

    Re: How big of a Genset do I REALLY need? Your advice appreciated...

    personally, I'd rather have a fixed 21 than a new 6. But, that's me.


    (And I don't believe I'm alone. There's a *very* nice '53 not far from me. Price isn't too far off. Been on the market for a long time. very small genny. People don't wanna have to deal with that when they buy a boat. I think that's why that boat hasn't sold. could be wrong)
    “Sentry”
    1977 Hatteras 70’ CMY
    #70MY313

  10. #10

    Re: How big of a Genset do I REALLY need? Your advice appreciated...

    Get the the big generator for when you need it, especially if you have inverter issues, etc.
    I always recommend Phasor but NL is good too. Not a fan of Onan, Kohler, and especially Westerbeke.
    CRICKET
    1966 HAT50C101
    Purchased 1985 12v71Ns
    Repowered 1989 with 8v92TI
    Repowered 2001 with 3406E

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