Tube heaters, are they any good?

[BlueChip]

De-humidifiers just such the air in from outside and that has unlimited moisture. They only really work when the area they are in is more moist than outside.

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Beg to differ, but thats just not true.

Using a dehumidifier you seal the boat and block all vents, then dry the air inside the boat to the level required. What's happening outside is largely irrelevant ( I appreciate that as the air pressure changes there will be some air movement inside to outside or vice versa but that will not be significant).
As others have said the X-Dry is the best dehumidifier to use because its a dessicant system and works at really low temperatures, it's not necessary to heat the boat at all for this to work.
We also leave all the interior lockers open and using a timer turn the fan on for a couple of hours a day to get the inside air moving and make sure that all the nooks and cranies are dry.

 

[Matt341]

A big thank you to everyone who took the time to reply to this thread.

I recently bought an 800watt oil filled radiator from B&Q but unfortunately it broke down after only 3 hours use, it kept overheating and tripping out.

I took it back and didnt feel confident getting another one so bought a Delonghi Convector which is powerful enough to heat the boat when we are staying onboard.

I then got 2x80 watt tube heaters from a local electrical store at £29.99 each. Im taking them down the boat this weekend and have also bought a timer, im thinking of putting them on from around 18:00 till about 14:00. Im hoping that they wont use to much power.

Im sure they will be ample to keep frost away and when we want the boat to be a temperature that we can stay on then we will use the convector heater.

A big thanks to everyone again.

Ian.

 

[haydude]

I put it on for about 4 hours a day in the morning and 2 hours early evening. After a week I was stunned to find the container was not full to the limit, it was about just over half.

Clearly you found out that on a timer the dehumidifier is almost useless. Do not use a timer! Would you put your fridge on a timer? Also put it on medium setting, when the boat will be nice and dry you will be able to set it down a notch. It will turn off on its own from time to time when necessary.

I have a B&Q model, white with the transparent blue tank. On average weather the tank fills in 2-3 days, when it rains it fills in 24 hours, so I leave it on the galley's top draining in the sink with the hose. When I use the yacht and I have shower towels to dry, it fills in just a few hours, but the towels also dry very quickly.

My yacht is nice and dry, I do not take anything home during the winter, and I store the sails below when I plan not to sail for a while due to weather, like lately ...

An heater is necessary only if and when temperatures get below zero, keeping the inside above zero prevents water that drips in between joints outside to freeze and crack them open. Also prevents fuel from freezing and water hoses from cracking.

 

[snooks]

It had been far too long since we went down to the boat, so when we got down there, all the cushions felt damp to the touch

We plugged in the new dehumidifier and went off to gunwharf for a few hours Christmas shopping

We weren't expecting much when we got back to the boat to be honest, but we were amazed that the cushions in the saloon, where the dehumidifier was, were already touch dry and the boat "felt" a lot dryer.

That night we were on board and the condensation built up with cooking, and having metal frames on our windows, so on went the dehumidifier again and the condensation went over the course of the evening!

Even over night when we were sleeping, we left the cabin door open, left the dehumidifier on, it kept the chill out of the night and none of the windows had condensation on in the morning, with over a litre of water in the tank it was a real eye opener.

We took it sailing over the weekend, and it's transformed winter sailing, even with heating oilskins can still still feel damp in the morning, not any more, and with the dehumidifier running it "heats" the boat to a pleasant level.

£150 for a dessicate dehumidifier you really can't got wrong.

If only we could get one that worked at anchor

 

[bob26]

I don't understand the point of solar vents.

Seems to me that since they only work during daylight they draw in air at its warmest (and therefore dampest). At night they don't work and when the temperature drops the damp air in the boat will reach dew point and some of the moisture will become liquid. The remaining air will then be drier because of this condensation. But come the dawn the solar vents promptly pump that dry air out and draws in nice fresh damp air from outside. Then at night the temp drops and another nice dollop of condensate is dumped in the boat...Or am I missing something here?

A naturally through ventilated boat ought to allow free passage of air at all times at the ambient external temperature and so avoid condensation.

All that assumes no occupancy let alone cooking or heating with fuels that produce additional water. I suppose a bank of solar vents might help with some of that in daylight but at night time when you are cooking dinner and snoring out all that damp breath their tiny apertures would do very little to replace all the damp air produced with the nice crisp and dry stuff freely available outside on a cold and frosty night.

The amazingly clever thing about the draft from a rainproof forehatch through to the vented companionway is that it works in the dark just as well as in the light.

Try opening your hatches a bit more, and buying some thermal underwear instead of burning money to run your dehimidifiers and heaters.

 

[AllanJ]

I dont see the point of heating a boat when the temperature is above about freezing. It is a very expensive activity in an already expensive hobby. Am I missing something?
I do see the point of dehumidifying if the boat is left unattended for anything more than a few days as the water is absorbed preferentially by almost the very things that molds just love to grow on - your clothes and sheets.
Warm air does hold more water than cold, as soon as it hits the window frames or other colder surface it will condense and drip on whatever is under it. A dehumidifier will reduce the water content in either hot or cold air as most work by cooling and condensing the air that is passed through them.
I see many comments against fans, but no actual facts to support the danger. Any electrical appliance has the potential to cause a fire (although most just melt or blow the fuse) and with high wattage appliances that is usually at the plug - and usually when they have not been used according to the manufacturer's instructions.
I would NOT use a fan (or anything else that has a high wattage) unattended where there was a risk of petrol, or other ignitable, vapour. This is solely due to the arcing produced in some switches which can provide the source of ignition.
Now... where are the matches?

 

[bob26]

Do boats freeze afloat?

I dont see the point of heating a boat when the temperature is above about freezing.

Do boats that are left afloat reach temperatures below freezing very often?

Even in the UK seawater has been known to freeze over I know. But for much of the winter water temperatures are well above air temperatures aren't they?

Monthly mean seawater temps at Shoreham for instance only dipped below 5 degrees centigrade six time in 20 years and never below 3 degrees. In Plymouth they only fell below 6 degrees three times and never below 4 degrees. The Bristol Channel was even warmer.

If that is the case then a heater on a frost stat shouldn't cost very much to run.

Put your boat ashore and its a different matter... you have to start thinking about draining stuff down that is not protected by antifreeze.

 

[bob26]

Lucky Largs

I dont see the point of heating a boat when the temperature is above about freezing. It is a very expensive activity in an already expensive hobby. Am I missing something?

No Alan - it is probably we who are missing something. I just noticed where you are based. I don't have sea temperatures for Largs to hand but according to University of Liverpool data, monthly sea Temperatures on the Isle of Mann (closest to Largs I could find I'm afraid) never fell below a balmy 7 degrees from 1971 to 2000.

Must be the Gulf Stream. Poor old Lowestoft had winter ranges of 4-5 degrees over that period and in 1986 less than two degrees for the whole of February.

The coldest seawater months are not January as I expected but Feb March and April.

 

[AllanJ]

I do believe that the Gulf Stream has quite a large effect on the west coast of Scotland (hence the tropical gardens at Inverewe in the NW!). Glad to know it's saving me money too. Although I understand that it is also responsoible for our disproportionate rainfall. Can't have it all after all.
I could squeeze up a bit and we can all huddle together for communal warmth, but under a big bimi.

 

[maxi77]

Whilst it is some time since I have seen sea ice on the coast of the UK (63/64) the air temperature, even in the sunny south often does fall considerably below zero and this can impact for example on fresh water tanks, and fresh water cooled engines. Also those of us on the east coast get little or no benefit from the Gulf Stream

 

[Oyvind]

Funny that nobody has mentioned chemical dehumidifiers.

Now, you can but the silly little boxes with salt in a small fabric pouch at the chandlers, but they are a HUGE ripoff.

The active ingredient is calcium chloride, CaCl2. It is commonly know as road salt, the stuff that is mixed with water and sprayed on gravel roads to subdue dust in the summer, or remove ice in the winter, and is really dirt cheap. It is also used in swimming pools.

Any company that deals in farm, pool or general chemical supplies should stock calcium chloride. The form of the chrystal has no significance, pool supplies are probably more expensive, but in this case the cheaper the better. Farm and chemical suppliers will probably sell this stuff in 25kg bags, which should last for years. Make sure to store it in an airtight container.

Take a cheap plastic colander, fill it with calcium chloride and place it over a bucket. You may also use nylon stockings or similar, just make sure that the brine that eventually forms has somewhere safe to drip and the bucket can not fall over, as the brine will attack brightwork. Since the stuff is so cheap, you'll probably want to place it in 2-3 places in a boat of any size.

 

[Coaster]

We have a 500W oil-filled electric radiator in our aft cabin, pemanently switched on with the integral thermostat set at about half. The boat is in the water and a mains electricity supply is connected.

The fore and aft hatches are left slightly open (it's a centre cockpit boat), allowing air in but keeping rain out. Internal doors are left open. As warm air rises I presume this arrangement encourages a gentle flow of air through the boat, in at the forehatch and out through the aft hatch. The result is a reasonably warm and dry boat.

 

[late-night-lochin]

I use a 240W oil filled tubular heater permanantly switched on during the winter with the front hatch locked in the "ventilate" position and my boat remains bone dry.

Chemical (desiccant) dehumidifiers will work at lower temperatures than refrigeration type ones but there is no point in using either type in the winter unless you are sleeping on board. I doubt then that a dehumidifier would stop condensation on cold window frames.

 

[humphrey231074]

I use 3 tube heaters in my boat one 1 ft length in the engine room under engine, one 3ft long in saloon, bilge board removed and heater sat on inner hull, one in forward cabin, all mounted diagonally on a nice piece of varnished plywood 6" wide x length of tube heater

All plugged into timer sockets, so never on after 9a.m and on every other hour after sun goes down.

works well and is the equivalent to a few light bulbs in power use, never permanently fix them as thats when you see corroded tube heaters when they are permanently onboard so they live in my garage at home when not needed on the boat.

bought them from this website.

http://www.yachtboatparts.com/tube-heater-with-brackets-1845-p.asp

 

[Spyro]

Can I ask how much you guys who leave heaters and dehumidifiers on for months at a time are spending on electrickery?

 

[maby]

Can I ask how much you guys who leave heaters and dehumidifiers on for months at a time are spending on electrickery?

We only left a dehumidifier running last year - no heating unless we were on the boat. A Meaco dehumidifier running continuously plus a fan heater running for several hours every weekend brought us a total bill of around £40 between late October and late March.

I think that is largely down to the efficiency of the Meaco - when it's running full power it consumes around 600W, but it soon gets the humidity levels down, then it drops to standby consuming just 20W unless the humidity rises. That works out at around half a unit per day - about 6 or 7 pence at the rate our marina was charging.

 

[Ex-SolentBoy]

Can I ask how much you guys who leave heaters and dehumidifiers on for months at a time are spending on electrickery?

Not a bean more. It is included in our ridiculously expensive mooring!

 

[maby]

Not a bean more. It is included in our ridiculously expensive mooring!

Really? That is unusual for unattended usage...

 

[snooks]

Can I ask how much you guys who leave heaters and dehumidifiers on for months at a time are spending on electrickery?

We have our dehumidifier running for around 6-8 hours a day on a timer switch. That and our battery charger, I think it cost us about £20 over the winter period. If we're spending time on board we'll plug in a fan heater or run the webasto.

We too have a Maeco and I think we have it on for 4 hours between 8 and midnight, then again in the morning. The theory (and that's all it is, no proof at all) is that as the temp cools the dehumidifier will be on to take any moisture out and warm the air. By the time the air has cooled down again (early hours of the morning) it will come on and take the chill and moisture out of the air for the day before coming on again in the evening.

Most of the time, it will just run on low power unless we're on board.

 

[Talbot]

I have 2 x 180w tube heaters 3ft long each connected to thermostats that are set to activate at 7deg They are located in each hull alongside the engine sumps.

I pay someone to look every week and also to check the meter.

The alternative is to drain all the fluids and not be able to use the boat at Christmas (when I will use the real heating system)

BTW if you are buyig tube heaters, go to greenhouse specialist suppliers, they are better value.