How to run boat at night when on water

Discussion in 'Sport Cruisers' started by Mark Searay, Dec 16, 2019.

  1. Mark Searay

    Mark Searay New Member

    21
    Nov 10, 2019
    Sydney Australia
    Searay Sundancer 375
    Mercruiser 6.5L x 2
    Hi
    As a newbie to boating , what’s the best way of running lights etc at night without destroying batteries?
    Is it recommended to run generator at night instead of running off batteries ?
    Any tips would be greatful
    With thanks
     
  2. Stee6043

    Stee6043 Well-Known Member

    Jun 1, 2015
    West Michigan
    1997 Sundancer 400
    7.4L Gassers
    I guess that will depend pretty heavily on what you consider "etc". :)

    A properly maintained set of house batteries should have no problem running your lights, a fridge or two and the occasional sink/head visit for a night or two without running the generator. If you're having battery capacity issues in the AM with these kinds of overnight loads you likely need some new batteries...or perhaps there are other electrical issues that could use some attention.
     
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  3. RollerCoastr

    RollerCoastr Well-Known Member

    Nov 15, 2007
    Cedar Point, OH / Miami, FL / MacRay Harbor, MI
    1997 400DA
    340HP 7.4 Mercruiser Bluewaters
    Garmin 741, 742, 8212, 24HD, Intellian I2
    1999 280BR
    Twin 250HP Merc 350 Alpha Ones
    Run the genny until right before bedtime to ensure batteries are fully-charged.
    • Convert the lights to LED
    • Minimize the time pumps run by:
      • doing washing etc. while genny is running in the evening
      • ensuring the the vacuflush system has no leaks (or shut it off at night)
      • ensuring the check valve in the sump is good so it doesn't cycle
    • Fill fridge and freezer with cold/frozen and dense items (beer cans and ice packs, frozen food etc)
    • Turn temp of fridge to a very cold setting while genny is running, then back up to a safe but higher temp off after shutdown
    • Avoid opening the fridge door until genny is running again in the morning
    Start the genny again in the morning to re-charge batteries, heat water, run pumps, make coffee etc.

    With healthy batteries and care, this routine can maintain 12V power indefinitely while running the genny 2-4 hours per day.
     
  4. sbw1

    sbw1 Well-Known Member

    Oct 10, 2006
    West Michigan
    This is listed in my signature
    This is listed in my signature
    We never ran our genny unless we needed it for heating IMG_4230.JPG or cooling. The batteries were robust enough to handle lights, TV, and stereo for several hours. Our refrigerator had a cold plate so it didn't run much.
     
  5. Express 390

    Express 390 Active Member GOLD Sponsor

    350
    Sep 14, 2018
    South Shore of Long Island NY
    1986 SeaRay 390 EC
    1993 SeaRay 290 DA single 7.4 /Bravo 2
    1992 SeaRay 230 DA 4.3LX Alfa drive
    Twin 454 Crusaders inboards 4 blades
    Like Stee6043 said a properly maintained 12 volt system should handle the demand with in reason. I can go out all day, run the Radio, Refrig, and whatever lighting needs to be used spend the night and be fine in the morning. And if you have too start the generator for a little while turn on the charger and put a little life back in the batteries !
     
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  6. Stee6043

    Stee6043 Well-Known Member

    Jun 1, 2015
    West Michigan
    1997 Sundancer 400
    7.4L Gassers
    Rarely will you find more practical, useful advice on the internet than "fill the fridge with beer cans". This is forum gold, people. :):):)
     
  7. RollerCoastr

    RollerCoastr Well-Known Member

    Nov 15, 2007
    Cedar Point, OH / Miami, FL / MacRay Harbor, MI
    1997 400DA
    340HP 7.4 Mercruiser Bluewaters
    Garmin 741, 742, 8212, 24HD, Intellian I2
    1999 280BR
    Twin 250HP Merc 350 Alpha Ones
    anything worth doing is worth doing right... :D
     
  8. electricaldoctor

    electricaldoctor Well-Known Member TECHNICAL Contributor PLATINUM Sponsor

    May 14, 2008
    Thousand Islands, Rockport, Ontario.
    1988 390 EC
    454 Mercruiser Gassers
    I had (4) 6 Volt Golf Cart Batteries in my 390 and could go out on a 4-day long weekend without any issues. (and I don't drink beer)
     
  9. Creekwood

    Creekwood Well-Known Member GOLD Sponsor

    Apr 26, 2009
    Oakville and Georgian Bay, Ontario
    '97 330 Sundancer, Raymarine C80 suite with radar, Mercury 310 Hypalon w/8hp Yammie 2stk
    2X 454 carbs w/ vDrives
    On my 330 I have my house bank replaced with two 6v golf cart batteries in series. They are 232 Amp hour rated. I have all of my lights replaced with LEDs now and a new Nova Kool refrigerator, which reduces power consumption. The fridge uses 5.2 amps while running so assuming 25% running time (I doubt it runs that often) there is over 7 days of power to run the fridge alone. Lighting and stereo during the day reduce that capacity of course and I would never run it down to zero. LED anchor lighting maybe is 3 watts = .25amps (20 watts = 1.7 amps if you don't convert LED). So you will consume about 2 amp hrs overnight each night if you leave LED anchor lights on for 8 hrs (14 for regular bulbs). So anchor lighting is not consuming much.

    I can easily be at anchor for a 3 day weekend without running the engines (I do not have a generator) and have enough to start the engine that shares the house bank at the end of the weekend (although it does turn over slowly).
     
  10. JVM225

    JVM225 Well-Known Member GOLD Sponsor

    Apr 8, 2008
    Farmingdale, NY
    2002 410 Sundancer, Monaco Edition.
    3126 Cats.
    Solid info!
    When we sleep on the hook we just run the genny for cooking, AC, TV etc. until it’s time to go to bed.
    Swapping all the bulbs in the cabin and cockpit courtesy lights to LED will cut down significantly on how much you draw and give you additional peace of mind.
     
    Express 390 likes this.

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