Dehumidifier drainage

[scurr]

Hi,

As a background: Since putting a seago ecodry on the boat yesterday afternoon I’ve got the relative humidity down from 70% to 46%. It’s producing a lot of water. Overnight just maintaining that % it filled its water tank.

The choice:
A) I don’t use it when I’m not here (I don’t think this is an option)
B) I drain it to the bilge and let the bilge pump take care of it
C) I leave the galley sinks seacock open and let it drain that way

Both B&C have drawbacks. E.g my bilge pump would have 2-3 extra cycles a day.

Second choice, what relative humidity do I aim for. The debice will turn off and on based on this.

Any best practice advice greatly appreciated.

 

[dunedin]

I leave the galley seacock open and drain via the sink. To my mind 46% is lower than you need. I use the dehumidifier on its most economical setting (highest humidity level - something like 50-60 if I recall correctly).
In a wet winter can easily be 80-90% on a wet day so keeping at 60% is a big improvement.
Try to keep well away from soft furnishings. And if afloat, tie it in place. It is incredible how much a boat can move around in a F10 storm, even in the most sheltered marina. And if you winter afloat, it is only a matter of time before the boat has to weather a proper storm or three.

 

[rogerthebodger]

I piped the condensate from my air-condition into my shower drain tank that then pumps out on a float switch

What's wrong in using the galley sink the galley seacock below the waterline

 

[B27]

Running it into the bilge is just bonkers, before you even look at dehumidifiers, you should have dusty dry bilges.
If you are afraid to leave the sink seacock open, then run the drain into a very big can that the water won't evaporate from, or mount the dehumidifier high an drain through a hole in the washboards

If you are trying to dry out a wet boat, setting a very dry target on the humidifier and running it in the warmest part of the day is most effective.
If you have a pretty dry boat and want to avoid condensation at night, a setting like 70% running overnight may be enough.

 

[scurr]

I leave the galley seacock open and drain via the sink. To my mind 46% is lower than you need. I use the dehumidifier on its most economical setting (highest humidity level - something like 50-60 if I recall correctly).
In a wet winter can easily be 80-90% on a wet day so keeping at 60% is a big improvement.
Try to keep well away from soft furnishings. And if afloat, tie it in place. It is incredible how much a boat can move around in a F10 storm, even in the most sheltered marina. And if you winter afloat, it is only a matter of time before the boat has to weather a proper storm or three.

Thanks for that. Mine is done on 5% increments. Will try it for a week on 55% splitting the 50-60 no. Can adjust from there.

And yeah my boat is moving a bit now so a decent blow and I could see it sliding into the sink.

 

[harvey38]

Are you sure you have sufficient ventilation?

We leave the three hatches cracked open about 5mm on the vent lock, even after a four month absence from the boat, there isn't a hint of dampness.

 

[dunedin]

Are you sure you have sufficient ventilation?

We leave the three hatches cracked open about 5mm on the vent lock, even after a four month absence from the boat, there isn't a hint of dampness.

Might depend where you are. The humidity in the outside air can often be very high, so the ventilation brings in more very damp air.

 

[Wansworth]

Ventilation is the cure for damp

 

[scurr]

Are you sure you have sufficient ventilation?

We leave the three hatches cracked open about 5mm on the vent lock, even after a four month absence from the boat, there isn't a hint of dampness.

At 2am with a cold draft it feels like I do, but no I don’t. There is the 30 holes in the washboard, the vent on the forward hatch.

 

[Wansworth]

When I left my boat for several months I made a simple box over the forehatch so it could be left ajar and a metal grill on the washboard…..no condensation

 

[James_Calvert]

+1 for draining into sink. But check the seacock is left open!

Also check the drain tube can't be dislodged.

(Obvious but...)

 

[jbweston]

On three boats over the years I've set mine to drain into the galley sink.

 

[Momac]

Hi,

As a background: Since putting a seago ecodry on the boat yesterday afternoon I’ve got the relative humidity down from 70% to 46%. It’s producing a lot of water. Overnight just maintaining that % it filled its water tank.

Not surprised the tank was full so quickly.

46% is unnecessarily low humidity. I have mine on the 60% setting and its fine with regard to preventing mould. But you are a good source of moisture so that is partly why the dehumidifier is creating so much water.

You wouldn't want to supply ventilation at the same time as using the dehumidifier as this will just use more energy. In fact block up vents when you leave the boat if you are going to leave the dehumidifier on.

But overall I suggest not using the dehumidifier when you are aboard. I don't use the dehumidifier if staying aboard overnight on the boat . This is where heating plus ventilation is more appropriate than a dehumidifier .

I also don't usually start to use the dehumidifier until November .

 

[thinwater]

D). Create an above the WL discharge point. For example, could it run out into the cockpit? I don't know your geometry. If it's in the dungeon, others have addressed that.

I've used DHs on two multihulls, but the sink drain was above the water line, so no issue.

---

The required RH is related to insulation and the lowest temperature of a chilled surface (the RH must be less than 100% at the temperature of the lowest cold surface--a psychometric chart can help). Are the windows double glazed? Are there cold frames? Is the humidity in the lockers and bilge space higher than the cabin (probably)? Is the hull cored? This will all be boat-specific.

pyscometric chart

 

[Momac]

The required RH is related to insulation and the lowest temperature of a chilled surface (the RH must be less than 100% at the temperature of the lowest cold surface--a psychometric chart can help). Are the windows double glazed? Are there cold frames? Is the humidity in the lockers and bilge space higher than the cabin (probably)? Is the hull cored? This will all be boat-specific.

pyscometric chart

Or keep it simple and try it on 60% and see how it goes .

 

[rotrax]

Running it into the bilge is just bonkers, before you even look at dehumidifiers, you should have dusty dry bilges.
If you are afraid to leave the sink seacock open, then run the drain into a very big can that the water won't evaporate from, or mount the dehumidifier high an drain through a hole in the washboards

If you are trying to dry out a wet boat, setting a very dry target on the humidifier and running it in the warmest part of the day is most effective.
If you have a pretty dry boat and want to avoid condensation at night, a setting like 70% running overnight may be enough.

Some boats - like mine - have keel stepped masts. These will always leak rainwater into the bilge. From the sheave slots and halyard exit slots. My stern gland is as dry as a Nuns Crutch, but after sponging the bilge sump dry, fresh water reappears after the first heavy rain.

We have a sump, about 27 inches square, 30 inches deep. After pumping with the hand bilge pump it has 1.5 inches of depth. Using the big electric bilge pump about 3 inches depth. It clears more than that, but then it runs back down the pipe.

Perfectly normal for a long keeler with a keel stepped mast. Apart from the sump, built in to collect the water, and any from other sources, all other areas under the sole are dusty.

 

[thinwater]

Or keep it simple and try it on 60% and see how it goes .

Exactly.

But the point is to remember that it is the coldest surface that condenses (very important if you are living aboard), and that an IR thermometer is very helpful in finding the cold spots.

I've lived aboard in the winter, and that is finding the condensation spots becomes important. Being aboard, cooking, and even breathing pumps the humidity up, and ventilation isn't much of a solution when it is sub-freezing.

 

[Martin&Rene]

I am often frustrated by the fact that people ask a simple question and do not say the particular situation that they are in. How much of a condensation/damp problem you have will depend on where the yacht is based. The size of the problem and solution will vary as to whether the yacht is in the Caribbean, the Med, up a small creek in the South of England, Scotland, on land or in the water.

In winter, my yacht is on land in Scotland alongside the Clyde and left unattended for 5 months. Whilst it is generally fairly wet outside, the daily temperature variations are not normally very large (so the air in the yacht is not expanding /contacting much) and temperatures below freezing are fairly rare. Using an electric fan heater and dehumidifiers, we make certain everything is dry just before we leave the yacht. Saloon cushions and mattresses are left propped up. We leave one of those crystal units in the instrumentation panel area and a greenhouse heater runs over night, basically just to generate some movement of the air. Everything is shut, so the only small airgap is between the sliding hatch and the washboard. We do not leave a dehumidifier running

When we get on in Spring, there is no smell of damp and often the crystal units have not been fully exhausted.

Humans and cooking are the major source of humidity in the yacht. If I had a yacht in the Caribbean, I would probably do something completely different.

 

[RupertW]

I am often frustrated by the fact that people ask a simple question and do not say the particular situation that they are in. How much of a condensation/damp problem you have will depend on where the yacht is based. The size of the problem and solution will vary as to whether the yacht is in the Caribbean, the Med, up a small creek in the South of England, Scotland, on land or in the water.

In winter, my yacht is on land in Scotland alongside the Clyde and left unattended for 5 months. Whilst it is generally fairly wet outside, the daily temperature variations are not normally very large (so the air in the yacht is not expanding /contacting much) and temperatures below freezing are fairly rare. Using an electric fan heater and dehumidifiers, we make certain everything is dry just before we leave the yacht. Saloon cushions and mattresses are left propped up. We leave one of those crystal units in the instrumentation panel area and a greenhouse heater runs over night, basically just to generate some movement of the air. Everything is shut, so the only small airgap is between the sliding hatch and the washboard. We do not leave a dehumidifier running

When we get on in Spring, there is no smell of damp and often the crystal units have not been fully exhausted.

Humans and cooking are the major source of humidity in the yacht. If I had a yacht in the Caribbean, I would probably do something completely different.

A lot of us have equal frustrations with those with boats in the UK who do not think dehumidifiers would help them and whose common trait seems to be a complete lack of a sense of smell. The “boaty” smell that so many UK sailors associate with a well ventilated boat is to the rest of us what we would expect to find in a garden shed at best and never in a place we would want to be sleeping.

The differerences are rarely about where the boat is kept, more about how pongy the boat owner is happy to have, and neither side every remotely convinces the other because we are all online and when someone inevitably says, “Well my boat doesn’t smell at all”, I know they are completely wrong but I can neither convince them nor find out for myself.

 

[Wansworth]

A lot of us have equal frustrations with those with boats in the UK who do not think dehumidifiers would help them and whose common trait seems to be a complete lack of a sense of smell. The “boaty” smell that so many UK sailors associate with a well ventilated boat is to the rest of us what we would expect to find in a garden shed at best and never in a place we would want to be sleeping.

The differerences are rarely about where the boat is kept, more about how pongy the boat owner is happy to have, and neither side every remotely convinces the other because we are all online and when someone inevitably says, “Well my boat doesn’t smell at all”, I know they are completely wrong but I can neither convince them nor find out for myself.

That Maurice Griffiths damp smell is part of the British yachtsman’s heritage