When to put on the heaters

[Flyfloat]

We run a 50ft flybridge boat which as is typical spends monday - Friday shut and locked, bobbing around in the marina (Hamble, UK). We always leave her with a dehumidifier running in the main saloon to try and keep any moisture at bay and also run an oil fired radiator in the master cabin.

Is there a rule of thumb as to when the radiator is necessary and when it is just a waste of electricity? Autumn has not been cold and as such is there a point when either the air or sea temperature drop to a certain point which will start to cause condensation inside the boat and thus warrants running the heat?

All advice gratefully received.

 

[wipe_out]

Can you link the heater to a thermostat set to around 5-8C which will then allow it to manage and regulate itself?

 

[Flyfloat]

Yes adding a thermostat is no problem. Is 5 - 8 c the magic number at which point we should be adding some heat and above which it will not make much difference?

 

[Bazzer]

I normally set my heater for about 10 deg c, which covers dew point temperature, I have a 42ft flybridge and it doesnt cost that much to run the heater and humdifier during the winter. It would cost a lot more to replace fabric interior if it started to get mouldy.

 

[BruceK]

No, there is no magic number. What you are looking to do is keep the interior of the boat above the dewpoint. As the winters here have relative high humidy and cold, the dewpoint will seldom be far from the mean average temperature. So if you keep your boat at the range given by Wipe_Out you should maintain an average temp higher than the mean. On hotter days that internal temp (8-10) may still be below the mean and you will get condensation, but as the temps drop back down it will dry out again rather than remaining wet throught the layup / winter season. You could run the heaters to maintain a higher temp, but you'd also consume more electricity than neccessary.

EDIT : Bazzer got there first.

 

[longjohnsilver]

I'd be tempted to buy another dehumidifier for the master cabin. If it's anything like mine it not only keeps things dry but also provides some background heat.

 

[Flyfloat]

If I buy another dehumidifier, where do you put the outflow pipe? Especially in winter when the boat is used less, I am concerned that the tank will just fill up and shut the machine down. The main saloon is galley up so it is easy to poke the pipe into the plug hole and it can run it's socks off.

I suppose I could leave the bathroom door open and put it there, if that is close enough.

 

[Bazzer]

If I buy another dehumidifier, where do you put the outflow pipe? Especially in winter when the boat is used less, I am concerned that the tank will just fill up and shut the machine down. The main saloon is galley up so it is easy to poke the pipe into the plug hole and it can run it's socks off.

I suppose I could leave the bathroom door open and put it there, if that is close enough.

I put my dehumidifer and heater in the gallery and leave all the doors open in bathrooms and bedrooms, works fine for me.

 

[longjohnsilver]

If I buy another dehumidifier, where do you put the outflow pipe? E

I suppose I could leave the bathroom door open and put it there, if that is close enough.

That's exactly what I do. I run 3 dehumidifiers, 2 draining into sinks in the heads, the other into the galley sink. The boat is always warm and dry when going on board.

I also leave all doors to wardrobes/ clothes storage areas open so they stay dry

 

[rafiki_]

I run a single dehumidifier, which seems to manage the moisture very well, draining into the galley sink. I put tube heaters on a thermostat set to 5C in the engine room and lazerette, and a separate heater in the main cabin again set to 5C.
The chap on the boat next to ours does not use any winter protection, and he has never had a problem, although he lives more locally than me, so visits when necessary.

 

[adey]

The ideal is to keep it cold and well ventilated. Heating one cabin will just increase the amount of moisture that the air can hold which will then condense when it finds something cold.
If ventilation's not an option a normal dehumidifier will work just fine unless really cold so don't heat anything, just leave all the doors and cupboards open. In the depths of winter a desiccant type will work better.

 

[Anders_P42]

I don't bother heating cabins above dew point, just run a Meaco DDL8 dehumidifier to keep moisture out of the air in first place. I leave two frost water heaters running, one in forward cabin another in Saloon and turn water pressure off and leave taps open. 1 x tube heater in engine bay on thermostat for 5C.

 

[Momac]

I have been thinking of taking my tube heater to the boat but will not switch it on until a decent frost is forecast. It goes in the engine bay.
Another heater goes near the calorifier. I am never convinced all the water has been drained out. At the moment I haven't drained the water off.
I don't put heaters in the cabins etc - but do use moisture traps . Rarely miss a weekend visit to get some air circulated. Never had a mould or damp issue. But agree a desiccant dehumidifier would be good such as he ddl8 mentioned above.

 

[Seastoke]

we have the ddl8 we also prop the mattresses up, for circulation

 

[Momac]

No sign of the weather demanding any frost protection heat at the moment.
I have filled some moisture traps with crystals . But no thoughts of draining off the domestic water or other frost protection.
The present weather forecast for next weekend looks pretty fair .
If that works out to be correct the boat will be going for a local spin and overnight stay . I don't think anyone will dispute the idea that using the boat is the best way of avoiding the development of damp related faults .

.

 

[vandy]

combination of cold nights and mild day temperature will create mould - best to set the heater to come on at day time to dry the air and not let the moisture and damp stay on inside the cabin

 

[Flyfloat]

Thanks for the advice all. Very useful