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AC while under way

Discussion in 'HVAC' started by wayne swisher, Oct 23, 2021.

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  1. wayne swisher

    wayne swisher New Member

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    Location:
    Missouri
    New to Southwest Florida boating from Midwest. I understand the need to run ACs a lot if not always-ish due to the heat and humidity here. However, my tech is encouraging me to run the generator and AC at all times while underway or away from shore power. His belief is that keeping the raw water moving keeps growth from getting a hold of the system. Seems like this overkill and unnecessary hours on the generator. We certainly don't want the humidity and its issues to take over the boat, nor any growth getting out of hand in the raw water system but wow.

    Thanks for your input.
  2. Pascal

    Pascal Senior Member

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    It would really help if you d bother telling us what kind of boat you have. Many modern boats have very little ventilation and will get unbearably hot inside.

    If you boat has good ventilation, then you may not need it. It depends on your comfort level as well

    personally in Miami, AC run 24/7 at the dock or underway, except a few days in winter after cold fronts.

    AC can sit unused but generators need to be used especially gas gens.
  3. wayne swisher

    wayne swisher New Member

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    Location:
    Missouri
    2019 Carver C40 Command Bridge. Yes comfort will trump other considerations. I don’t want to run the generator (diesel) unnecessarily if the intent is merely to keep growth out of the raw water system. So trying to determine the actual “need” or not.

    Is growth so aggressive here as to encourage essentially full on use of AC (assuming it would require gen) regardless of the weather conditions or while off of shore power even for a few days or so?
  4. olderboater

    olderboater Senior Member

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    Let's discuss your home in Missouri first. Do you nor run A/C all summer? We sure did in NC. Every day. Pretty much from April to September. So now you're talking an area of perpetual summer and why wouldn't you run it?

    Also, don't think of it as A/C but as HVAC, controlling your climate, dehumidifying. Our HVAC is on in our house, in our office, on our boat at all times. It actually runs as required to maintain conditions. We want to come inside to comfort. Few days or so without it, only the five days of unseasonably cold weather each year and on those days we'll have the heat on.

    As to the growth. Hopefully you've already made arrangements for bottom cleaning. Every month year round but more likely every three weeks during at least half the year. That tells you the level of growth. Simple facts that things grow better in warmer water.

    If we're not at the dock, our generator is always running. Not just for A/C but for all other electric needs, for refrigeration, freezers, cooking, hot water, everything on board.
  5. wayne swisher

    wayne swisher New Member

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    Never had a boat with AC before. It's not that I don't want to run the AC when it is needed. If it is hot/uncomfortable, then I'm all about it. My concern is more about the raw water circulation for the AC. If we are in a situation when AC is not needed/desired thus off, does non-circulation of raw water truly allow for growth in the system to get out of control? Fully understand the bottom cleaning needs. It seems logical that similar growth would occur in the raw water lines. However, does the circulating raw water reduce or minimize growth in these lines? Thanks.
  6. Pascal

    Pascal Senior Member

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    I don’t think not running the AC for a day is going to increase growth in the raw water circuit.

    one issue we have in SoFl is with little white shells growing in the hoses and coils. Problem is that they die when AC is off and water drains back. Then they get loose and clog up the circuit at the first barbed fitting.

    This could be what your tech was referring too.

    For comfort just run the generator and air con unless it’s just after one of the few strong fronts.
  7. olderboater

    olderboater Senior Member

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    You're presenting a hypothetical that is so unlikely except the one cold spell each year. Now you say Southwest FL but no more specific. So I picked Naples. Average high 84 degrees, average low 67. Summer average high is 91 and average low is 76.

    Outdoors is great but when you come inside you'll want it cool and dehumidified. Your cooling might run very little at times but the system will be active and will be dehumidifying. When it's not on an active cycle, then the load on the Generator will be low. Let me ask you this. If you didn't need the HVAC system active, what about all the other electrics on the boat? Do you have a system to support them without the Generator? Adequate batteries and inverter?
  8. Capt Ralph

    Capt Ralph Senior Member

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    <-----
    Were up river in Satsuma FL. Leaving onboard for a short trip tomorrow to Jax and some offshore fishing later in the week.
    The weather is nice and will not be running the gen-sets or A/Cs while operating. An inverter will keep all the 120Vac options powered up while running.
    Large forward hatch, saloon side windows and after door and hatch keeps the boat nicely ventilated while under way.
    Either on the dock or at anchor, the A/Cs are running at night with one of the gen-sets as needed.
    Now, When it's hot as heck or a day of rain, the hatches are closed and A/Cs & gen-set is running while operating.

    I have witnessed some boats require a battery charger on 24 x 7. This does require a gen-set to run 24 x 7. To keep the gen-set loaded, the A/Cs are usually running.
    I don't think Carver developed this mad mode of operation.

    IMO, your tech may be off base here with his explanation "keeping the raw water moving keeps growth from getting a hold of the system" .
    Again IMO; If it is barnacles or berber carpet fouling, it needs food. It's the moving raw water that brings in the nutrients that feed the growth.
    It's your diver you want to feed.
    Operating or not, It's going to get fouled.

    I do truly believe that an A/C system will foul less NOT running. At the dock or underway.
    Last edited: Oct 23, 2021
  9. ranger58sb

    ranger58sb Senior member

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    I might be sorta-kinda am coming to agree with that, maybe. :)

    We spent some time in Ft. Myers this Summer, and the strainers seemed to mostly clog with grass... perhaps being sucked in by the pump because it was running all the time. I wondered then if NOT running the pump (and ACs) would have reduced that build-up. Temps would have made that grim.

    Then too, we sometimes had a few small oysters or crabs or whatever in there, perhaps drawn in by suction rather than intentionally finding their way into our inlets.

    (I've since dropped a piece of copper tube into the strainer basket, said to possibly be prophylactic... last time I cleaned a strainer, now up here on the Chesapeake... but haven't yet checked to see if there's any change. Not sure there's a way to measure potential change, anyway, given all the variables.)

    FWIW, we now have to run the genset while underway, anyway -- AC-only freezer/fridges, no inverter yet -- so also ran AC (aircon) at the same time for temp and humidity control. The boat would have been very uncomfortable in July and August without aircon underway, though. My goal is to make aircon underway optional, but probably won't get there 'til next Spring...

    In any case, it helps to have a system set up for easy/fast strainer cleaning. Open, remove basket, clean the bowl, insert spare clean basket, close, prime (if necessary)... everything back together and turned on in about 10 minutes.

    -Chris
  10. Pascal

    Pascal Senior Member

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    If you are in an area with a lot of grass and crap install external strainers aka south bay strainers at your next haul out. They re fantastic. Nothjng comes in, nothing to clean Just a quick scrub by the diver

    personally I think that water sitting in the lines will cause more growth but hard to prove... who cares just deacale the system every year and enjoy a cold bait
  11. Fred DiMaio

    Fred DiMaio New Member

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    and now i am try8ng to fix my AC because I didn't run it for months......lesson learned run the AC at all times and the Generator you want the impeller wet and not dry rot....
  12. Capt J

    Capt J Senior Member

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    The best thing you can do from the generator is to run it often with a load (A/C). The best thing you can do for your interior woodwork and finishes is to run the A/C and not leave the portholes and stuff open underway where salty air is getting a fine layer of salt on everything. It's highly unlikely an owner will wear out a generator. But plenty of them die from lack of use.