Batch load RMH on my boat

I am the proud servant of the John T. Naden a retired 1955 Canadian Navel water tanker. In the two years I have had her I have added an upper living room and transformed the 4 water tanks into one working area. This gives me 18'x42' of usable area downstairs. this area has my shop, two staterooms, fireplace, wood rooms and other. The wood stove is a S244 Century that is only two years old and is on its last legs. cracked glass,
SS baffel is rotted out etc. I would like to build a batch feed RMH along the centerline (one foot off center) easily countered by movable ballast. My total area for stove and mass is 8' fore and aft. 7.5 ' height and would like to keep the width under 2'. I have an existing 6' chimney. My thoughts are of a mass 6' long 4' high 18" wide. mass would contain 20 feet of 6" duct, 6-90's, and 2-45's leading into the existing chimney. I thought of the outside of the mass to be built on the outer layer of 4x8x16 cinder block with the cavities lined up to allow for convection exchange through the night. this mass I can secure to the center bulkhead by welding rod to the bulkhead and tying into the mass as it is built up I would use my plans of Ernies 6" unit and a 33 gallon barrel, would like to modify into cast fire chamber/chimney, would like to use external air makeup, the lower area has a continues small fan extracting moist air off the floor area to outside, would like to keep that system balanced. Any thoughts would be gratefully considered
Scott

I have no hands on experience beyond an unforeseen cast core, so all can really offer is : WOW!
YOUR BOAT IS COOL AS HELL!!!

OK, got that out, now to like and flag this thread, for the love of shear awesome.

Sounds like a fascinating project, with a novel twist of having to handle regular movement of the vessel. The number of elbows you describe is excessive for a 6" system; 20' of duct plus 5' equivalent for each elbow gives some 50-55' which is too much for a standard 6" system to handle. Given the space constraints, I would suggest making a bell instead. You could easily get enough internal surface area to absorb the heat while having little drag and good draft.

About 3 am I came to the same conclusion about the length of pipe. Started thinking about water tank for mass storage. Easy to weld,add 2 gallons of boiler treatment to the water and a diapram expantion tank, would run app. 12 feet of pipe inside the tank and 3 90's. 4 feet of pipe,1 90,2 45's and 12 feet to the rain cap.

cool project!

i wondered the same thing about the boat rockin and rollin. did you have to attach the wood stove to the floor?

i seen a thread on here about an insulated riser, off the top of wood stove, then into a bell. could you see that working with the bell being on second floor? added bricks to the stove and bell for some thermal storage.

again very cool project sir!

Using a water tank for your mass sounds like the best idea. No masonry joints to worry about, materials compatible with the rest of the boat, and you know how to deal with hot water tanks. As long as you keep it separate from the heat riser so there is no extreme cooling there, you should be fine.

The part that does need to be masonry is the combustion core. The base of it should present no unusual issues, but the heat riser will have to be anchored to prevent shifting in heavy weather. A sheetmetal shell around a cast riser will give it inherent rigidity, and you will need some kind of standoffs or anchor struts to the barrel and thence to the structural supports. It would probably be a lot easier to handle that if the barrel top is removable so you can access those connections with the barrel in place.

I wonder if you might want a flue bypass external to the mass and going straight up the chimney, for startups when the water is cold. I expect the full length of flue inside would be a draft-killer when cold, and with the heat transfer efficiency and fluidity of water, it would take a lot to warm up. I would imagine being able to gradually divert the flue gases into the tank passages while the water warmed up would make life easier at times.

As a matter of fact, you may want to do some research into how much flue pipe you really want inside the mass tank. There is such a thing as being too efficient in heat removal and killing the draft most of the time.

Ok I looked up the bell idea, not for me as I am looking for thermal mass to radiate heat through the cold nights. It takes about 3 hours high burn to get the upper house to 18C.from about 2C. Plus there is little room to spare around the upper stove pipe.
Keep them coming.
Scott

A bell is an effective heat storage medium if made with plenty of mass; that is basically what the Russian stove and other masonry heaters have done for centuries. But it will take up more space than a water heat storage medium, which is an important consideration on a boat.

Scott Davidson : beautiful project, and obviously a labor of love, Without trying to cause any unearned awe on your point, I can say that we are entering interesting
times !

A fellow member describes it this way- after the creation and 'proof of concept' build of the first few Rocket Mass Heaters RMHs, Science was left trying to Reverse
Engineer the build and ''Discover the Science'' that makes these builds so amazing!

Initially, we were met with Scientists who could not run tests on our RMHs with the equipment that they then had on hand ( We were busy building 100,000 + More!)

Then it was- ''modify your stove so that we can test it !'' and finally, Crafty D.I.Y. Builders/Operators who found out how to modify/use Existing Equipment to finally
test our Equipment and produce even greater gains in good clean high Temperature fun with fire !

All this boils down to taking a good look at modifying your system to possibly shrink your Thermal Mass Base after your Rocket Burner base and then include a final
'' Bell'' into your system !

We will have to know a great feel more about your proposed layout !

There are many kinds of 'High Temperature Cement out there most of it rather $pendy, but definitely Portland Based Cement will fail quickly if used within the core of
your Rocket burner,and your burner base.

The case for iron/ steel within that core area is even more critical ! A google search for High Temperature Hydrogen Attack, Hydrogen corrosion, Hydrogen blistering
and Hydrogen / Steam Embrittlement will give you an appreciation of the materials that we DO work with, and a sense of some of the early difficulties we had testing
Rocket Mass Heaters.

This will be a very interesting build to follow, please share lost of pictures and sketches during your build !

Actually, while your RMH is running it should be capable of totally replacing the fan system you are using to reduce moisture on the decking areas of your Ship, running
the two of them together will probably be very difficult / impossible, but knowing that your rocket is a good backup system for a powered unit should be a +

I am looking forward to Seeing Our own ''Elderly Naval Man'' Ernie Wisner who is forum moderator for the Rocket and Wood stoves Section weigh in on this topic !

For the good of the craft ! Big AL

You might find good links to technical info in this thread on the donkey32 forum:
http://donkey32.proboards.com/thread/1096/hot-water

well I have spent the night calculating wood btu etc. right now I burn 12 pcs of dry fir/hemlock mix, 4 lbs per pcs. is about 250,000 btu input in about 12-14 hours. my stove is rated at 75% so give it 40%, Im getting 100,000 btu into the boat. none at night as I don't wake up enough to feed it. A 250 gallon 1/8" water tank will absorb 250,000 btu going from 50f to 150f. thats 10 pcs of wood. that same tank will radiate app 18,000 btu/h (if painted black) so in 6 hours 108,000 btu, the water would drop to 110f or so. This would give me the night heat I so desire, this would require 5 pcs of wood to replace so about 2 hours and the rest of the days burn 2 hours?? goes into the ship. Consistent heat is better for everything. My humidity downstairs is 54-64% while some heat is on. gets to 76% when cold for a few days. Read somewhere that Ernie and Erica burn 35-40 lbs a day in a 4 burn during the winter, I may yet have even heat and save some wood.
I have tried making a drawing of the build area using google draw, its crude but may explain my plan. It will include all the proper finishing and details not mentioned.
I have been advised by someone who knows (Ernie) that I should not consider the batch unit for this application and best to go with the J unit, that's good enough for me
The heat produced downstairs is transferred up by:
1: the chimney is single wall up to the ceiling, then super pipe,
2: a 12" dia. pcs of pipe inserted in the deck allowing heat to flow upstairs,
3: the stairwell.
The basement and living room insulation is r12 on the walls r20 under the basement floor and in the living room ceiling. The steel deck between the living room and shop can transmit heat to the jointly connected steel hull which sits in 42f water most of the year.
The upper house has 3-3x6 windows, 2-4x6 windows, 1-5x5, 1-5 foot slider, 1-3x4 xo galley window, and 2-1.5x5 panes in the two exterior doors. Like I said a wall of glass, but when you live in this beauty you have to see it!

Scott