advice on heating my boat please

lw395 said:
Alternatively, a thick duvet on a freezing cold but dry day can be bliss.
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^^This^^ or better still a down sleeping bag. I sail all year and have a Webasto fitted but don't use it when singlehanding and only when directly instructed by SWMBO.
 
David2452 said:
Forget the capital cost, therm for therm electricity is cheaper than the diesel you would burn in a heating system.
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Capital cost of Eber is what? £800 for a kit years ago IIRC.
£2 a night for diesel? £5 even, it's several years before the fuel becomes the main cost.

I was comparing cheap mooring perhaps £15 a night vs £35 per night for marina with electricity.
£20 a night extra cost, how many of us actually do more than 10 winter nights?

OTOH, there is real value in having heat underway on a damp cold day.

If you own a boat for ten years then look back, it's easy to regret not stumping up for things like heaters to make the best of it.
 
Burnham Bob said:
We're going to be sailing through the winter. The boat is a Trapper 500. I can't afford (or justify) a permanent heating arrangement like an eberspacher. Old remedies like a flower pot on the cooker seem a little unsafe/ineffective. Small gas fired heaters look ideal (the ones that use a gas cartridge) but of course the danger is carbon monoxide (and I am told condensation). Has anyone ever used one? Or what about the spirit heaters like the Origo?

We have shore power so if I go into a marina I can use a small fan heater. But if we wanted to be adventurous and anchor overnight what does the forum recommend. Naturally we wouldn't leave it on overnight and SWMBO would expect tea in the morning with me switching the heat on before she gets up.

All serious suggestions considered!
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Yes. I used and then ripped out a gas heater - one of those catalytic ones. Basic chemistry says you cant burn hydrocarbons like gas or alcohol inside your boat without generating both carbondioxide and water inside the boat. So my recommendation is to buy a second hand truck heater like Mikuni and install that as is works like your home CH and ejects the water and CO2 outside the boat.

I would not go near the crude charcoal burning gadgets. At least the gas heaters make a serious effort in their design to avoid generating carbon monoxide. charcoal heaters are as sophisticated as an open fire and they are a real risk IMO. That apart, a pal installed one and burnt his boat to the water line.
 
For a Trapper 500 you could suck a peppermint. More seriously:

As you are only contemplating the odd night out, light the oven and crack open the forehatch. Maybe use the flower pot.

Only a plutocrat would buy a thousand quids worth of kit for the odd jaunt.

I rather regret getting rid of my catalytic gas heater, you could fit one but I don't think it is worth the bother. They are fine provided they have fresh air to feed on. You need ventilation fore and aft and any moisture will exit the boat via that route, along with similar waste gasses produced by the crew.
 
lw395 said:
OTOH, there is real value in having heat underway on a damp cold day.

If you own a boat for ten years then look back, it's easy to regret not stumping up for things like heaters to make the best of it.
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+1 and although you can plug heaters in when on the marina, we find that the air changes you get with a Webasto/Eber (if you duct the fresh air intake outside) help to dry everything out in winter. We used to use oil filled radiators on the marina but they weren't nearly as effective (prob should have got a cheap fan heater).

off up there tonight so just hope it fires up!
 
now we are onto generators thrumming away

KISS

one bread tin, two flower pots, four candles

simps

or go to a marina and buy a fan heater from argos

I think that marina hopping makes really good sense in the winter

the odd night out is fine.... but the problem with winter sailing is not so much the cold but the length of the evenings - dark by five

if you are in a marina you have dry heat, wifi and lots of power to run the laptop and you can even take a stroll ashore to your local Harvester or Hungry Horse.

spending a couple of grand on a webasto does not make much sense to me - of course if you own one you can always get stuck into the threads about problems with them

the trouble with the candles and flower pots is that the threads on why they don't light are so few and far between

D
 
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dylanwinter said:
now we are onto generators thrumming away

KISS

one bread tin, two flower pots, four candles

simps

or go to a marina and buy a fan heater from argos

I think that marina hopping makes really good sense in the winter

the odd night out is fine.... but the problem with winter sailing is not so much the cold but the length of the evenings - dark by five

if you are in a marina you have dry heat, wifi and lots of pwoer to run the laptop and you can even take a stroll ashore to your local Harvester or Hungry Horse.

spwending a couple of grand on a webasto does not make much sense to me - of course if you own one you can always get stuck into the threads about problems with them

the trouble with the candles and flower pots is that the threads on why they don't flight are so few and far between

D
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man talks much sense. only comment I would make is that if you have problems with an eber, replace with a mikuni.
 
dylanwinter said:
the trouble with the candles and flower pots is that the threads on why they don't flight are so few and far between

D
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That's the problem with carbon dioxide poisoning from candle by-products of pyrolysis: your brain's speller checker goes to sleep permanently. ;)

Come on, Mr W, you know that candles are inefficient and dangerous, yet you persist in promoting them as the answer to heating problems. I think you are allowing your romantic tree-hugging tendencies to overcome your otherwise rational, creative and entertaining output.

A tea light candle weighs (typically) 10g, and burns about 1.2mg every second - based on my observation that one candle lasts about 2.5 hours in still air. Candle wax has a heat value of about 40kj per gram. The heat energy produced is about 30watts (http://protonsforbreakfast.wordpress.com/2013/11/05/candle-mass-and-candle-power/ 40 watts for a large candle).

I haven't the foggiest idea how quickly heat (as warm air) flows from the inside air of a cabin, out through ventilators, windows hull, deck, hatches, etc by conduction, convection or radiation, but it is going to be a lot more than that produced from a small candle. The emotional warmth you get from (not) seeing a candle hidden in a flowerpot is the only possible benefit, apart from the deposition of tiny tiny particles of carbon over all the inner surfaces of the boat.
 
sarabande said:
That's the problem with carbon dioxide poisoning from candle by-products of pyrolysis: your brain's speller checker goes to sleep permanently. ;)

Come on, Mr W, you know that candles are inefficient and dangerous, yet you persist in promoting them as the answer to heating problems. I think you are allowing your romantic tree-hugging tendencies to overcome your otherwise rational, creative and entertaining output.

A tea light candle weighs (typically) 10g, and burns about 1.2mg every second - based on my observation that one candle lasts about 2.5 hours in still air. Candle wax has a heat value of about 40kj per gram. The heat energy produced is about 30watts (http://protonsforbreakfast.wordpress.com/2013/11/05/candle-mass-and-candle-power/ 40 watts for a large candle).

I haven't the foggiest idea how quickly heat (as warm air) flows from the inside air of a cabin, out through ventilators, windows hull, deck, hatches, etc by conduction, convection or radiation, but it is going to be a lot more than that produced from a small candle. The emotional warmth you get from (not) seeing a candle hidden in a flowerpot is the only possible benefit, apart from the deposition of tiny tiny particles of carbon over all the inner surfaces of the boat.
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Stitch that ;)
 
sarabande said:
That's the problem with carbon dioxide poisoning from candle by-products of pyrolysis: your brain's speller checker goes to sleep permanently. ;)

Come on, Mr W, you know that candles are inefficient and dangerous, yet you persist in promoting them as the answer to heating problems. I think you are allowing your romantic tree-hugging tendencies to overcome your otherwise rational, creative and entertaining output.

A tea light candle weighs (typically) 10g, and burns about 1.2mg every second - based on my observation that one candle lasts about 2.5 hours in still air. Candle wax has a heat value of about 40kj per gram. The heat energy produced is about 30watts (http://protonsforbreakfast.wordpress.com/2013/11/05/candle-mass-and-candle-power/ 40 watts for a large candle).

I haven't the foggiest idea how quickly heat (as warm air) flows from the inside air of a cabin, out through ventilators, windows hull, deck, hatches, etc by conduction, convection or radiation, but it is going to be a lot more than that produced from a small candle. The emotional warmth you get from (not) seeing a candle hidden in a flowerpot is the only possible benefit, apart from the deposition of tiny tiny particles of carbon over all the inner surfaces of the boat.
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I take it that you have not actually tried it on a small boat.
 
sarabande said:
... I haven't the foggiest idea how quickly heat (as warm air) flows from the inside air of a cabin, out through ventilators, windows hull, deck, hatches, etc by conduction, convection or radiation, but it is going to be a lot more than that produced from a small candle. ...
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I tried to make some very crude estimate of conduction losses alone, on a heater thread on the other forum, based on a very simple approach employing thermal conductivity data (http://www.engineeringtoolbox.com/th...ity-d_429.html).

Representing a boat as a GRP cylinder 10m long, of 1.5m radius and 2.5cm wall thickness, I estimated heat losses for a 1 degree inside/outside temperature difference as follows: 173W and 1300W for GRP thermal conductivity values of 0.04W/m.k and 0.3 W/m.k respectively (a wide range of GRP TC values from a very quick web search).

The difference is obviously large and the estimation method very crude – and I may have applied it incorrectly, simple as it is. I had hoped that a physicist or engineer might check my estimations - and preferably provide better ones. But in the absence of that, the results confirmed my feelings about how little effect on internal temperature a tube heater of say 80W would be likely to have, and they do the same for me here.
 
Doesn't the average person give off about 100W of heat? That's about three candle's worth. Can't you fill your boat with people? Invite everyone in the anchorage over for a drink....
 
dylanwinter said:
I take it that you have not actually tried it on a small boat.
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Would you take a small caravan used as a lambing shed in winter on Exmoor as a suitable trial site ?

Dylan, you are being like King **** (EDIT.... Bloody swear filter. I wrote C N U T) over the "candles as heater" claim.


Have a look at Hydrozoan's outline above. For his upper range of thermal loss, you would need about 40 (four zero) candles.
 
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The candles might give you a nice glow though, that's a symptom of CO poisoning...
As well as dulling the sense of cold.
 
sarabande said:
... Have a look at Hydrozoan's outline above. For his upper range of thermal loss, you would need about 40 (four zero) candles.
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And that's for just a 1 degree difference between inside and outside - but I do ask that somebody please check what I've done (link gives method, and the low-end GRP TC value) in case my aged brain has let me down! :dread:
 
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