marine dehumidifiers

[xcbxer]

First new thread - looking for any commentary/experience with marine dehumidifiers such as the Mermaid Dry-Pal, eBac CD30 ($600) or even cheaper the D-H-51 at edehumidifier.com

Bottom line,sure it looks like the way to go to avoid condensation if one has the amp hour solution to support it, but it doesn't seem to be widespread installed or accepted. The book Warm and Dry got a bad review from an old salt (he said nothing there except common sense and some cfm tables). And since the manufacturers pay no attention ultimate cabin comfort it's left to us individual owners, boat by boat.

Saw one short positive comment on dehumidifiers from WuWei on the Ventilation Options thread, but could not get my post to stick there. Briefly, I want to extend the summer sailing season by two months without doing a major insulation job. So here's the detailed story on what I'm intending to do and any critique is welcome.

Boat - Beneteau 473, 500 AH house bank, Freedom 2000/Xantrex 1000, low hull liner, teak decks
Location - Lake Ontario
Useage - currently on 30A shore power with lots of day sails, weekend cruises and longer runs to the 1000 islands.

HVAC strategy:
First started by looking at installing air conditioning. Then a 3.5 KW genset to drive the new A/C and existing inverter/charger when away.

Also have a few cold feet family members and would like to extend the sailing season to include May and October. That leads to finding a mild weather heating solution which apparently leads directly to risk of condensation. I have no plans to insulate the interior. There is a general consensus that circulation and ventilation are key factors to consider.

Problems - Half the docks around this lake aren't equipped to carry a 18000 BTU load (ie reliable 30 amps), so a 2 zone A/C becomes an expensive option. Air conditioning does remove condensation but hatches should be mostly closed - in too many ways that's a dumb idea when 'out there'. Running a diesel is prohibited in some anchorages in the 1000 islands. With our reasonable summers (maybe only 10 boiler days) a full capacity air conditioner is looking like a noisy floating condo application with low R.O.I.

Now the heating solution definitely will be going in, probably an Espar air to air and ducted. I am not getting much support from my know-it-all crowd because I am leaning towards also installing a marine dehumidifier. This combo should provide humidity control and plenty air movement. I will help it along with good return paths, openings to closets/storage/bilge areas, and solar vents all generally circulating the air back thru the engine/battery areas and out the stern. When I get the Espar I will work out the make up air equation. I was told they generally set up for 100% recirculation, but I think some controlled mixing should be possible.

Still have room for an A/C unit (with insulated ducting) so might just put in a 9000 BTU to knock the hot days down a bit at the dock, and remove summer humidity without turning on the dehumidifier. Should able to use common ducting for the heat and A/C. The smallest Mase 2.2 KW genset would then suffice.

Major comfort versus major complications. Life used to be simpler but then I bought a bigger boat.

[paul77]

I have the DH5. It works okay, seems to keep things at 50% RH. I
like the low power consumption too.

I expect better results when I finish the hydronic heating install, due to higher ambient temperature and more airflow.

Climate here is very different from Ontario winter though.

[xcbxer]

Thanks for the feedback. Your 46 footer and maritime climate isn't far off my spring/fall application.

Do you have the unit under a settee or out in the open and how's the noise level?

These units make a bit of heat, is that a problem on hotter days (if you have any) or do you run A/C?

[paul77]

I have it next to the galley sink which is in the center of the boat.

If you can find the space, permanently mounting with some ducting seems good.

It's not quiet, we turn it off when at the boat and put away when
sailing. I haven't noticed it generate any heat.

There's no reason to have a/c here.
Having grown up in southern Ontario, the Humidity in Seattle definitely seems lower. We don't get the condensation on everything in the cold months.

The dh5 is a pretty low cost thing to at least try out. The mermaid was smaller so might fit out of the way. Fitting into the ducting for the heating system sounds good.

In another thread someone mentioned that ventilation is counter to running the dehumidifier. However we do have two solar vents and four passive dorades. I haven't tried closing the boat up to see an improvement.

With your size you should consider hydronic over forced air for heat.




Someone else noted in an older thread that ventilation

[WuWei]

I just have a normal small house dehumidifier. Cheap, and works great on shore power. I take it off and store it in the back of the truck when we go sailing. Regardless of the one you use, it definitely makes a HUGE difference- although we keep the solar vent and fan running, and have a louvered vent in the companionway. No mold! And it is always nice and dry when we enter the boat. We also have a small "window" AC unit that we use when it is really hot- we built a special companionway door for it and it works pretty good in the summer. We also have one of those round plug-in marine heater things- you know, putty colored with the holes on the top. It helped, but I wasn't a huge fan.

We did look at the marine dehumidifiers and ACs- yikes on price. The hubby thought I was nuts when I lugged that dehumidifer on board- I was not happy to open the boat and seeing condensation on the ceiling, so I came up with my own solution. Now, he's glad we do it, and doesn't grumble when we take it off for trips. Trip-wise, we use 110V/12V fans (that have rechargeable AA batteries) and the WindScoop to keep good ventilation at anchor. We also have screens for the hatches, so we can keep bugs out at night. On a 30' boat, space and battery conservation is a premium, so I can't see getting a cruiser AC unit. But, on a bigger boat, they sure are nice. Whatever you choose depends on your needs and budget.