Really small heater for 18ft boat

[William_H]

Cabin heating

From someone who knows nothing of cabin heating but has to comment...
On a small boat you surely have a cooker. Hopefully spirit cooker for safety. This surely would be useful for heating the cabin.
Now ventilation and CO are a real concern. You don't want to have to get up and close the hatch when you turn off the heat. I would go for a chimney over the cooker. Perhaps with a small fan to induce removal of gases. The chimney could be straight up from the cooker through the roof or better turning to go aft to the aft cabin bulkhead. If the chimney is made of copper or Ali then the heat of exhaust gases will heat the chimney and so transfer heat into the cabin. The chimney should I would think have a funnel that can be fitted over the cooking flame which would radiate the heat. With a small electric fan the chimney could be quite small diameter. 50mm?
Well that is what I would try for a start. Followed by a home made heater with chimney mounted down low. Perhaps drip feed of diesel kerosene etc. good luck olewill

 

[Contest1]

I use the night lights, I place them just under an couple aluminum v section grill sheets, I feel this heats the trapped air causing convection. Certainly makes for a snug cabin and little condensation.
Have thought of putting some heat bricks in the oven before bed and then opening the oven door when the gas is off. Just never got round acquiring the bricks yet.
Centaur

 

[NUTMEG]

Sounds interesting, where abouts on your blog - to lazy to go through it all

Er! Not sure. Several pages mention it. Do the search thing, type in Victory and it will do the work for you.

 

[dylanwinter]

what are

I use the night lights, I place them just under an couple aluminum v section grill sheets, I feel this heats the trapped air causing convection. Certainly makes for a snug cabin and little condensation.
Have thought of putting some heat bricks in the oven before bed and then opening the oven door when the gas is off. Just never got round acquiring the bricks yet.
Centaur

so for your Centaur - which is pretty big

how many candles, where do you put them, what is a V section grill sheet and how do you support the sheet over the candles

D

 

[V1701]

Thinking the same Pete, I was going to get an Origo5100 but you may as well get a Tilley lamp that gives light out as well - the only worrying thing is the lighting procedure and maybe where to hang it from considering there could be a lot of heat coming from the top. I presume a Tilley Light is the best one to go for... It burns Paraffin (Kerosene) whereas the Origo is meths so not sure if there is any advantage to either...

Chris

My oil radiator is much more effective when on the floor than when on a board on one of the settees (which it sometimes is to keep it out of the way - not much floor area in the Vega). If you hang the lantern up high I'm pretty sure you won't feel anything like the benefits of the heat that you would with the same heat source at floor level...

 

[Zagato]

I have a Victory Heater as well. Mine is a basic Primus. It works ok but I have made a big copper bell to protect the deckhead. I always crack the hatch open and have never found a problem with condensation. As I am ashore for 5 months, over the winter, that is when it gets most use.

There was some chat about Tilley lamps a few years ago and this alternative brand were well thought of:

http://www.petromax.com/lanterns.htm

It is what I would go for, if not for the Victory.

Thanks for the link, the only thing that worries me about Tilley & Petromax lamps is having a flare up Petromax do look good though

Here is the link to the Victory lamp mentioned earlier.

http://www.theblindsailor.co.uk/2011/11/30/more-about-the-victory/

 

[vyv_cox]

Thanks for the link, the only thing that worries me about Tilley & Petromax lamps is having a flare up

I have owned my Tilley for about 30 years. Before that I had a BiAlladin for about 20 years. Both have been used extensively, indoors and out. Neither of them has ever had a flare up. It is possible to allow liquid paraffin into the lamp if the preheat has not been left for long enough. This can cause a small flare but you soon learn not to do that as the carbon needs to be cleaned off the glass before starting again. Once the lamp is up to temperature 'flare-ups' don't happen.

 

[Lodesman77]

In nearly 60 years of camping, motorhomes and sailing I have never once left any form of heating on overnight, and that includes such activities in temperatures down to -20C.

A Tilley lamp takes a lot of beating for evening use, giving out plenty of light for cooking, reading, etc and loads of heat sufficient for a much bigger boat than yours. Then into a decent sleeping bag and turn the heat off. Used Tilleys are widely available for low cost and the parts to refurbish are not too pricey.

Good insulation on the hull and topsides of the boat make a massive improvement at little cost - PBO had an article on it in the past year. We followed much of it, fitting aluminised sheet with airpockets from Homebase, has made a big difference.

+1 - a very good summary.

I have a Vapalux, basically the same as a Tilley but is the type issued to the forces so good supply of new (I paid £65 for mine) as well as second hand on eBay, e.g.:-

http://www.ebay.co.uk/itm/VAPALUX-M...ing_LightsLanternsTorches&hash=item337cf94da5

For reference, it keeps my 28 footer T-shirt warm when 5-10C outside, jumper warm at around 0C.


I would also second the hot water bottle in a good sleeping bag...

.

 

[Searush]

FWIW, I have a wall mounted LPG Catalytic heater - probably asbestos & 40 years old. I expect it is simply illegal today, however it will burn your face off if you walk too close, even on half power. I light it & open the main hatch by about 6".

The hatch is under a sprayhood (full cockpit canopy now) so rain/ snow won't come in. 10 minutes later & the large-ish cabin (31' pentland) is toasty warm. On the lowest setting it keeps the cabin warm, even with the hatch open.

It allows me to get undressed & into the sleeping bags & I can then shut the hatch & turn it off. It remains warm for several minutes while I settle.

The addition of a full cockpit canopy has made the boat noticeably warmer in winter, but it is not a cheap option unless you can make it yourself. It significantly reduces the wind & hence draughts.

As Dylan and others have implied air changes (ventilation) will soon replace all the warm air with cold. So while ventilation is essential for survival, & minimising condensation, too much is bloody cold. You need to find the right balance for you in your boat. I suspect a small boat needs more percentage ventilation than a large one as your breath is the main cause of condensation once the heater has been turned off & your breath will be a larger proportion of teh air in a small cabin.

Finally, I said sleeping bags, because I use two cheap 2-3 season bags, total cost under a tenner, but as warm as any £100 4 season one. I have a cheap "mummy" bag so that I can cover my head (a lot of heat is lost thro the head as it has massive blood flow thro it) & it covers the shoulders well (again a high heat loss area due to the adipose fat deposits). The outer bag is just one of our normal summer "zip-together to make a double" bags.

If it is really cold I will wear a vest & use a Damart bag liner I got when canoeing. I have woken to find ice on the inside of the windows & under the decks (in the lockers) as well as all over the outside of the boat.

In such really cold conditions it is possible to almost completely close the Mummy bag so one is partly rebreathing exhaled air. This maintains heat in the body & reduces condensation. I understand that Victorian street kids were known to rebreathe each others breath while cuddled together to stay alive sleeping on the streets.

In fact, there are good lessons to be learned from those much less fortunate than us. Cardboard & newspaper are wonderful & cheap insulatorr - and, as already mentioned, dogs have a higher body temperature & make good (if perhaps a little smelly) hot water bottles.

 

[Georgio]

Another vote for a Tilly, I think mine was about £20 off ebay and it just needed a new mantle (and a spare).

Works well and kicks out lots of heat (and light). I always light it in the cockpit and then bring inside once it has been running for a minute or two. Keep the hatch open a crack and switch it off before sleeping.

Not tried tealights but would be tempted to give that a go as an over-night solution as long as they were very well away from anything that could catch fire.

As other have said, there is lots to be said for a thick sleeping bag, the only problem is getting out of it in the morning to put the kettle on, brrrrrr!

 

[aquaplane]

In the search for keeping warm, I rather like the traditional advice on treating hypothermia...

"Put subject into a sleeping bag with a fit companion."

I'm thinking large sleeping bag, small wriggly Yorkshire lass. Fond memory tells me them are very warm...

It doesn't work with a Lancashire lass though.

On my First 18 a storm lantern took the edge off the cold. We couldn't put the washboards in from the inside either so there was only a bit of shower curtain keeping the cold dark night out.

 

[prv]

As other have said, there is lots to be said for a thick sleeping bag, the only problem is getting out of it in the morning to put the kettle on, brrrrrr!

Perhaps a good case for the "Mucusbag" suit mentioned by a previous poster?

Pete

 

[prv]

I have woken to find ice on the inside of the windows & under the decks (in the lockers) as well as all over the outside of the boat.

Was there ice on the bag as well? If not, it was obviously leaking heat

Pete

 

[dylanwinter]

time for this film

Was there ice on the bag as well? If not, it was obviously leaking heat

Pete

http://www.youtube.com/watch?v=aUs1VDR2kkQ

 

[stevebrassett]

As an alternative to a thick sleeping bag, I use a 2-3 season one, plus a cheap duvet from Tesco. Gives me quite a lot of flexibility.

 

[onesea]

Perhaps a good case for the "Mucusbag" suit mentioned by a previous poster?

Pete

Got them love them.

SWMBO bought us some last Christmas, we have not (yet) gone to the showers in them but the day will come .

What we find is we have a second sleeping bag (Summer one) we use as blanket not been cold since...

 

[Halo]

Have a few of those hand warmers from an outdoor shop (you boil them up to change them to liquid phase then activate them to release heat as they solidify). This is reversible so you can use them loads of times and boil them up when at home or have mains electric. Have a few in the sleping bag with you

 

[LittleSister]

What makes absolutely the most difference for me is having a blanket to put over my legs doubled when seated in the cabin. I never would have imagined how much difference it makes - try it sometime.

Like Searush, we have a LPG catalytic heater, and it's great on our 23 footer. Ours is a 'Mini-catalytic heater' (there is also a midi and perhaps a maxi) that is made by a Scandinavian firm called something like Altoz, but is sold by various chandlers and others (e.g. Mailspeed Marine) under different names.

The 'Mini' is supposed to give out about 0.75 kw. It's certainly a boon on a small boat in winter. We normally have to turn it down (simply by partially turning the off the gas tap to it) after a little while. Our boat is well ventilated (small vents forward, over the cooker and in the washboards, plus a big 'funnel' vent in the enclosed heads compartment), but I intended never to have the heater on whilst asleep. However, I did fall asleep with it on once (fully clothed after a long passage!) and suffered no ill effects.

We intended ours to be wall mounted, but despite checking the published dimensions we found these didn't include some projecting part, so it actually lives in a small locker, is on a flexible hose, and is lifted out and sits (on it's own built in stand) on a step under the cooker when in use.

 

[mikemonty]

About 270 watts instead of 190 watts

Vics candles (once the units have been readjusted):
Nett Heat of Combustion 43.1 Mj/kg
= 43100 kJ/kg

each candle 20 g
= 0.02 kg
6 candles
= 0.12 kg

total heat 5172 kJ

burns for 8 hours
= 28800 seconds

rate of heat generated 0.179583333 kJ/s
= 179.5833333 W

using Dylans candles:
Nett Heat of Combustion 43.1 Mj/kg
= 43100 kJ/kg

each candle 14 g
= 0.014 kg
6 candles
= 0.084 kg

total heat 3620.4 kJ

burns for 4 hours
= 14400 seconds

rate of heat generated 0.251416667 kJ/s
= 251.4166667 W

I like Dylans candles better! Vics seem to burn slower.
But the average male human generates about 100 W at rest - without having to be set on fire or replaced every 4 hours.
So you can either: forget the candles, wrap up and insulate yourself and keep 40% of the heat the (better) candles would generate efficiently close to your body.
Or not wrap up, light the candles and use that heat to warm the air as well as your own 100 watts (which is not a limitless supply!), which you would be squandering on heating the air in the boat.
OR you could warm the air with the candles to reduce the temperature gradient across your insulating clothing for a while, before you are ready to get into your bed and thus add another layer of insulation, and allow the boat to get cold once the candles go out.

 

[VicS]

Vics candles (once the units have been readjusted):
Nett Heat of Combustion 43.1 Mj/kg
= 43100 kJ/kg

each candle 20 g
= 0.02 kg
6 candles
= 0.12 kg

total heat 5172 kJ

burns for 8 hours
= 28800 seconds

rate of heat generated 0.179583333 kJ/s
= 179.5833333 W

using Dylans candles:
Nett Heat of Combustion 43.1 Mj/kg
= 43100 kJ/kg

each candle 14 g
= 0.014 kg
6 candles
= 0.084 kg

total heat 3620.4 kJ

burns for 4 hours
= 14400 seconds

rate of heat generated 0.251416667 kJ/s
= 251.4166667 W

I like Dylans candles better! Vics seem to burn slower.
But the average male human generates about 100 W at rest - without having to be set on fire or replaced every 4 hours.
So you can either: forget the candles, wrap up and insulate yourself and keep 40% of the heat the (better) candles would generate efficiently close to your body.
Or not wrap up, light the candles and use that heat to warm the air as well as your own 100 watts (which is not a limitless supply!), which you would be squandering on heating the air in the boat.
OR you could warm the air with the candles to reduce the temperature gradient across your insulating clothing for a while, before you are ready to get into your bed and thus add another layer of insulation, and allow the boat to get cold once the candles go out.

Well done for finding a cal value for candle wax. I did not try very hard so made a rough guess ... should have said (now corrected) 46kJ/g of course

Not sure you can justify the 10 figure precision of the final results you quote.

180 and 250 watts respectively would have been more appropriate as final answers.