Small Boat Heaters

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  • 07 Dec 2018 01:54
    Reply # 6949221 on 4911731

    If anyone is still interested in a heater, I stumbled across this one while looking for steering mechanisms: http://www.faymarine.com/plansite/fire_design.htm

    The rest is my rambling on one of my ideas for small scale heating.

    Having done some experimenting rocket mass heaters it caught my eye. A RMH would have no place on a boat (unless it was much larger than any I can imagine myself in) but some of the ideas are still of interest.

    1. Heat the body, not the air.
    2. Hot surface temperatures are bad
    3. Storing heat is good
    4. Burn fast
    Radiant heat will feel better than air temperature and transfers heat directly from the heater to the body, but radiation falls off at the inverse square for distance (which means that if you are twice as far from the heater you will get you will get 1/4 the heat not 1/2) so close is important.

    Direct heat transfer if even better. Most RMH have a built in heated bench with which to warm one's body directly... may not transfer well to a boat unless one has hot water heating from a running engine, scratch that.

    Insulation is like a resister, the warmer the heater is, the better it's heat goes through the walls to heat the outside. So cooler (just shy of being able to damage skin) surface is more effective for the fuel input.

    Saving the excess heat in mass is good, except there is not really much room in a boat (particularly a light weight one) for such nice things.

    As others have mentioned, burning fast is better for heat extraction and produces less harmful flue gas. So aside from not being as likely to kill you, it uses less fuel. Both of these things are good for a boat... but hotter is not.

    Maybe there is somewhere in between. Burning fast has a number of problems besides loosing heat out the flue and through the cabin walls. It requires better shielding, it is easy to get burned and it uses the fuel faster. However, I am thinking of two things (maybe three or four by the time I am done) that could help.

    1. Phase change heat storage
    2. A Bell heat exchanger
    Space is limited, but I have noticed that whatever the size of the heater, there is not anything mounted above it. It is nice to be able to also cook on it, this is true. And while cooking could be achieved at chest height, most would rather not have something hot way up in the air where an errant motor boat wake might fling it on top of someone. However, placing a second chamber on top would allow capturing a good deal of the "waste" flue heat. This is called a bell (in the masonry heater world).

    So this is great being able to get more heat before the flue gas and the heat in it leaves, but this would leave to much heat at once. Phase change is the answer I think. Put a second box around the small stove and fill it with tin which melts at about 230C and absorbs much more heat to melt than it does in just heating (lead would be possible too and might hold more heat for volume). This box would have to be welded shut (as in sealed) so that molten metal didn't get all over things. Now as even 230C is very hot the next thing to do would be to put insulation around the outside of this box. (big grin as I wait for sarcastic remarks about keeping the heat in the heater) The insulation is probably not very thick (welders blanket?) but allows the surface temperature to remain relatively cool... maybe we can get it down around 100C or less.

    The idea is that the fire burns for a short while till the tin has melted and then let die. The Stove continues to shed heat for hours as the Tin "freezes". The insulation keeps the cabin from over heating with a fast burning fire and also lets the heat keep radiating longer.

    A further idea is that the tin boxes could be detachable and placed under bedding or seating... or for that matter placed under a pot to boil water.

    I realize that because a boat has a small inside space, most people are not worried about saving fuel so long as it works and keeps them warm and dry. So maybe the world is not ready for such ideas... gotta make one.

    Last modified: 07 Dec 2018 01:59 | Anonymous member
  • 08 Aug 2017 16:57
    Reply # 5018924 on 4911731

    A thought on small heaters I have a pansy stove , stainless steel and goes on charcoal.

    Puts out a lot of heat and can be turned down to a very gentle heat that seems to last along time. good for a 30 ft boat 

    Pete j

  • 29 Jun 2017 13:41
    Reply # 4923885 on 4911731

    I can also recommend the Dickinson Bristol. We had one on our boat Miss Molly I and despite having a week of snow piled up on the coachroof one winter in Vancouver BC, it kept things toasty belowdecks. It got a bit warm for cooking on when we got down to the Sea of Cortez though :-(

  • 23 Jun 2017 09:33
    Reply # 4913852 on 4911731

    I used to cook on a Dickinson 'Bristol' diesel cooker, at sea and in harbour.  It did not have a chimney damper, which it should have had, but it did have a fan, which was used on occasion in particularly gusty conditions.

    Last modified: 23 Jun 2017 09:34 | Anonymous member
  • 23 Jun 2017 06:44
    Reply # 4913735 on 4912409
    Jonathan Snodgrass wrote:
    Paul Thompson wrote:
    As I said I start the heater when I come on board and it stays on until I leave... however long that may be. To date 3 months has been it's longest continues run. 
    Paul, is this only whilst moored or do you or would you use it whilst sailing?
    I don't think I'd use it under sail offshore but I have use it under sail in sedentary conditions (and short hops) when coastal sailing and I've had no trouble. Offshore or when it gets bouncy, I think I'd rather not run it.
  • 22 Jun 2017 21:39
    Reply # 4913271 on 4912499
    Arne Kverneland wrote:

     However, the Reflexes are prepared for installing an air-feed tube with intake above deck. This will fix the downdraught problem and let one sail with the heater on.

    Arne


    Arne, Thank you for that.  

    I have checked and our heater appears to be a Refleks 66 M.  It probably dates from the build of Lexia in 1978 ie almost 40 years ago.  

    When we purchased the boat the stove was derelict and dangerous.  (Amongst many other problems, the stove was missing the burner turbo swirl device which looks a bit like a large corkscrew and sits in the flame.)   

    However, I received very good support from Lockgate Stoves near Derby, UK: www.lockgate.com .  They supplied information and advice and parts.  Ultimately I took the stove to them and they did an overhaul for a modest charge for 2 hours labour plus parts.   

    The parts list supplied by Lockgate does indeed show an installation with an air intake through the deckhead alongside the vent pipe with the air intake leading down under the stove.  (It does not show a fitting for the air to go up into the stove but there may well be one.)

    That diagram states:  "When the Refleks oil stove has to be mounted in the pilothouse or at a place where pressure differences may occur - either from the motor or by wind  influence, eg open doors - the mounting has to be done as shown." 

    Cheers, Jonathan  


  • 22 Jun 2017 13:10
    Reply # 4912499 on 4911731
    Anonymous member (Administrator)

    The smallest diesel potburner heater/cooker made by Reflex, is the little cube-shaped model 71M (25 x 25 x 25cm, 9kg) It puts out about 1.6kW at highest setting and about 0.6 at lowest.

    I know a young German couple who lived on board their 25’ wooden boat (in Stavanger) for a couple of winters. That model 71M kept the boat warm and dry as well as adding a cooking plate.

    Unlike the Taylor heaters, the Reflex heaters last for decades, as the combustion chamber is stainless.

    Now, diesel pot-burners are vulnerable to down-draught. I have seen both Taylors and Reflexes suddenly being blown out. (..I never got around to install a sparkplug to quickly restart my Taylor...). However, the Reflexes are prepared for installing an air-feed tube with intake above deck. This will fix the downdraught problem and let one sail with the heater on.

    I think the Model 71 would be a fine heater and aux. stove for a boat like SibLim.

    Hopefully these two links to the Reflex site works, 71M and specs.

    Arne


    Last modified: 22 Jun 2017 16:10 | Anonymous member (Administrator)
  • 22 Jun 2017 12:39
    Reply # 4912409 on 4911863
    Paul Thompson wrote:
    As I said I start the heater when I come on board and it stays on until I leave... however long that may be. To date 3 months has been it's longest continues run. 
    Paul, is this only whilst moored or do you or would you use it whilst sailing?

    We have the smallest Refleks heater on Lexia.  It is very effective.  

    I understand from the literature inherited with the stove that they were originally designed to be used on Danish fishing vessels, apparently whilst at sea.  

    However, I would not like to use it whilst sailing.  (But to be fair we have never needed to use it whilst sailing.)  

    I remember that David Tyler has written that he did not use his Refleks whilst sailing.  


    Last modified: 22 Jun 2017 12:39 | Anonymous member
  • 22 Jun 2017 10:03
    Reply # 4912321 on 4911731

    I put a Refleks 66 in Ivory Gull, and a Dickinson in Tystie. I preferred the Refleks, as the fuel feed was at the side, not the bottom of the pot  and so didn't get clogged with flakes of carbon dropping into it. Also, the Refleks had a device to clean out the fuel feed without dismantling.

  • 22 Jun 2017 09:15
    Reply # 4912251 on 4911863
    Paul Thompson wrote:They cannot be bought off the shelf in NZ but it's not problem to import one from Norway, they were pleasant people to deal with. See http://refleks-olieovne.dk/66mk/

    Odd that, seeing as how they're made in Denmark :-P

    However, you can buy Dickinson heaters here, in NZ and they have a nice little window so that you can watch the flickering flame.

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