Dehumidifier vs. AC?

Discussion in 'Sport Cruisers' started by rbryn, Jun 23, 2009.

  1. rbryn

    rbryn Member

    254
    May 27, 2009
    Wilmington, NC
    2003 260DA
    350Mag MPI Bravo® III (re-powered 2013)
    Our 260DA is in a wet slip and is equipped with AC/Heat and Dehumidifier. When leaving the boat for a few days is it better to leave the AC on, or the Dehumidifier?

    When we took delivery, they recommmended to run the AC at 78-80 when it's in the slip. My brain is saying "would it be better to run the dehumidifier"?
     
  2. MAKC

    MAKC Member

    499
    Oct 23, 2006
    Windsor Locks, CT / Milford, CT
    2005 320 Sundancer
    Twin 6.2 Mercruiser w/V-Drives
    i use the dehumidify setting because it will run once an hour even if the temperature goes below the A/C temperature setting. On A/C mode, the system wont run until the temperature gets to, or higher, than the setting you have the thermostat set to. So if you leave the A/C mode on and the thermostat set to 78, if the temperature in the cabin stays at 77 degrees for a week, the system never runs. In dehumidify mode, it runs once an hour to take the humidity out of the air in the cabin.

    Hope this helps
     
  3. fc3

    fc3 Just another eclectic geek TECHNICAL Contributor

    Nov 12, 2006
    Northern NJ
    1999 Sea Ray 330DA
    Twin 7.4 MPI (310 propshaft HP) V-drives
    Twin Mercury Marine marinized 7.4L L-29 V8s
    Cast iron block w 4-bolt mains
    Use the dehumidify mode. You can adjust the programming so that it runs every X hours for Y minutes.
     
  4. Turtlesboat

    Turtlesboat Minister of Media TECHNICAL Contributor

    Feb 4, 2007
    New York City
    1996 450DA, TNT, Caribe dink w/15hp OB.
    3126 427HP TD transmissions
    I love the de-humidify mode. works perfectly.
     
  5. sbw1

    sbw1 Well-Known Member

    Oct 10, 2006
    West Michigan
    This is listed in my signature
    This is listed in my signature
    We let our boat sit with nothing on. Not a problem. The only time we use the air is when cruising and then it runs about 24/7. It gets very hot down below when we are not on board, but I don't notice downside and it cools down quickly when we use it.
     
    Bugsy22 likes this.
  6. Robski97

    Robski97 Well-Known Member

    Jan 15, 2007
    North Bellmore, NY
    44DA
    Cummins QSC 8.3's
    MAKC,
    Dehumidify mode bypass's t stat set point. IT follows the Dehumidify program like Frank said and can be fully programmed. Run time and time it runs fully adjustable

    Rob

    PS i use Dehumidify mode all summer here in NY
     
  7. gerryb

    gerryb Well-Known Member TECHNICAL Contributor

    Oct 12, 2006
    Somers Point, NJ
    "On Vacation"
    2006 40 Sundancer
    Raymarine E125 & HD Radar + Garmin 5208
    QSB5.9 380 Cummins
    I also use the dehum mode all summer long and found the out-of-the-box settings to work quite well re x's and y's...
     
  8. jimdavi

    jimdavi New Member

    271
    Feb 4, 2008
    Minnesota
    320 Sundancer
    5.7L 300 Hp V drives
    HU mode, never damp in the boat when I return after a week.
     
  9. rbryn

    rbryn Member

    254
    May 27, 2009
    Wilmington, NC
    2003 260DA
    350Mag MPI Bravo® III (re-powered 2013)
    Thanks... I've already learned alot by reading through all the forum posts over the past few weeks.
     
  10. MAKC

    MAKC Member

    499
    Oct 23, 2006
    Windsor Locks, CT / Milford, CT
    2005 320 Sundancer
    Twin 6.2 Mercruiser w/V-Drives
    yeah i should have worded that better. :)

    I use the defaults for the dehumidify mode but yes it is all adjustable. Great feature for sure!
     
  11. sbw1

    sbw1 Well-Known Member

    Oct 10, 2006
    West Michigan
    This is listed in my signature
    This is listed in my signature
    Just curious as to why things are damp without running the A/C? My experience is things are really hot below but cool off rapidly when opening the boat up or running the A/C. Why spend the money to cool or dehumidify when the humidity pretty much goes to whatever the ambient humidity is when you open up the cabin?
     
  12. Kameroo

    Kameroo Member

    683
    Feb 1, 2007
    Louisville, KY
    12' Kayaks
    Human
    It can get pretty hot here, so I have two reasons for running the AC when we're not there:

    1) Better for the interior trim. Our non-Sea Ray has some laminated strips that start to get soft when it approaches 100 degrees.

    2) Better for the refrigerator. It works less with an 80 degree cabin. I figure it will last longer as we use electricity for the AC.
     
  13. Robski97

    Robski97 Well-Known Member

    Jan 15, 2007
    North Bellmore, NY
    44DA
    Cummins QSC 8.3's
    Kameroo brought up a great point. The stress on the refrigeration equipment in a 100 Plus cockpit or cabin.

    Also some boats tend to smell if left sealed up in the heat. Guess its a preference thing.

    Rob
     
  14. bmac

    bmac Active Member

    Jan 11, 2008
    Holbrook, NY
    2006 58 Sedan Bridge, Walker Bay Generation 390 RIB w/40hp Yamaha, 2014 Wellcraft 232 CC w/Yamaha
    MAN 900 CRM
    I run the AC 24/7 from the time the boat goes in the water in May until it comes back out in October. When away from the boat I leave it set at 62 and 68 when we're on it. The only time the AC is off is the 10 seconds it takes when transitioning between shore power and generator.
     
  15. Cincy Aquaholic

    Cincy Aquaholic Active Member

    Mar 15, 2009
    Cincinnati
    290 SS - 2016 Ford F250 Powerstroke
    Twin 5.7 with Bravo 1's

    If I'm reading this correctly, I believe its the cumulative effect of prolonged exposure to moisture that would cause problems- musty, mildewy, basement smell or worse, mold. I use the HU control on my unit. It seems like that should do a good job of circulating and drying out the air as designed. Now that its heating up and getting steamy I need to reprogram it and have it kick on more frequently and for longer periods.
     
  16. sbw1

    sbw1 Well-Known Member

    Oct 10, 2006
    West Michigan
    This is listed in my signature
    This is listed in my signature
    One of the benefits of keeping a boat at home is you don't need to have the fridge running unless you are cruising. Our fridge is still off and clean. I do run the a/c when the fridge is on because we are living on the boat. When done cruising, we defrost it and shut it down. I've had good luck with fridges and oderless cabins so far, and we are certainly no stangers to humid conditions. It was in the 90s today and muggy.
     
  17. barryg

    barryg Member

    959
    Jun 24, 2007
    Fort Lauderdale
    2005 320 Sundancer, Garmin 5208
    Twin V-Drives 350 Mags
    In the summer when I'm not on the boat, I use the AC and set it at 79.. With it approaching the mid 90's here now, I've done the HU settings before and found the cabin dry but way too hot.. As it gets cooler I'll just use the HU setting..
     
  18. rbryn

    rbryn Member

    254
    May 27, 2009
    Wilmington, NC
    2003 260DA
    350Mag MPI Bravo® III (re-powered 2013)
    I never thought about the heat in the cabin. I was more concerned with the overall humidity (it's not uncommon to be 90+ degrees and 80%+ humidity here). It sounds like the best bet would be to run the AC on the hottest days, and the HU after it cools back down a bit.

    Thanks for all the replies.
     
  19. marbelliana

    marbelliana Member

    46
    Oct 19, 2015
    Somers Point, NJ
    2007 Searay Sundancer 310
    Twin Mercs 6.2L V-Drives
    "Marbelliana II"

    Previous boat: 22' Robalo R227
    Twin 6.2L Mercs
    On the subject of AC, my Searay AC (Cruzair) always runs the fan whether the compressor turns on or not. As I understand it, apparently there is a setting that will allow me to only run the fan with the compressor is running. 2007 Searay Dancer...anyone know how to program that in? I didn't see it on that little "instruction" manual that's stuck inside the thermostat door!
     
  20. carterchapman

    carterchapman Well-Known Member TECHNICAL Contributor SILVER Sponsor

    Mar 25, 2008
    Lake Chickamauga/Marietta, GA/Ft. Myers, FL
    2006 Sea Ray 58 DB
    MAN CRM V8-900s, Twin Disc Drives; Onan 21.5 Generator
    A great resurrection of a 9 year old thread!! We leave our 4 A/C's in the HU mode in both FL and TN when we are off of the boat. No problems when we return....We leave the bridge air (#5) off when we are gone...
     

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