vertical marine boilers

[cmbellman5]

I am now well and truly hooked on live steam since I was given a Wilesco model missing a few bits to fix.
Two radio controlled boats and several engines later, I am hoping to fulfill my desire to watch my new 30" scratchbuilt fantail launch, steam away by Xmas.

I built a couple of single cylinder wobbler engines which happily run on 20 psi air, so I built some boilers to fire them. All the time I wanted a reasonable looking 1/12 scale boiler to suit my boat.

I built several with ever increasing numbers of flue tubes until I got to 2 1/2" od by 3" heightboiler sitting on a 2" firebox.
This produces about 20 psi and runs the single cylinder singleaction wobblers well. The heating area is 30 square inches.
I am now building a 3" od boiler with 60 square inches of 3/8 tubing that I hope will give me the 35 psi I need to drive my twin cylinder double action wobbler engine.

Does anyone out there have some tips re boiler design for small boats?
I am happy to exchange pictures and drawings

My next project is a sidewheel paddlesteamer, most likely with a beam engine

[kno3]

Hi and welcome. Why don't you post some pictures of your work in progress? That way it's easier to make a recommendation.

Regarding boilers, I would say that horizontal ones are generally better, because they allow a lower centre of gravity. Vertical boilers are often top-heavy and might run into stability problems.

The boiler design also depends on what you intend to fire it with. If gas or pressurised liquid fuel (alcohol etc.) which use a torch-like burner, you can build a boiler with a larger fire tube and diagonal water tubes in it. It is probably the most common boiler type in model boats and locos nowadays.

If solid fuel (Esbit, Sterno, even coal) or liquid burner with wicks, a different type of boiler is needed, with more room for the burner.

If you need plans, you can contact me on Yahoo Messenger or e-mail.

[cmbellman5]

I have built the 3" boiler and tried it out.
The single cylinder ran well, but I cant get 20 psi out of it.
How do I attach photos? to show what I have done.?
I am using solid fuel, meta tablets, and I built a huge fire under the boiler, but to no avail.
Perhaps the vertical boiler cnot get to 30 psi without using gas?

[kno3]

Either the solid fuel tablets don't burn hot enough (which is quite possible), or you boiler doesn't have enough heated surface to transfer all the energy from the fire to the water.
Gas certainly burns hotter. Alcohol or petrol vaporising burners are also good.

[boilertester]

Hi cmbellman5
Solid Fuel tablets will never get your boiler hot enough to get to 35psi and maintain it for any length of time. your vertical tubes are just allowing the heat to go straight up the chimney, you really need fewer fire tubes but put water tubes across them, these will restrict the hot gases and give time to heat the water.  You can do no better than read the series of articles by Peter Arnot called "starting in steam" and "continuing in steam" from Model Boats magazine June 1988 to October 1988 and March 1990 to July 1990. www.myhobbystore.com should be able to help with these back issues or photo copies of the articles.
If you need more help, you can contact me by email.

Cheers

Paul R

Boilertester

[cmbellman5]

Thanks for that Paul.
I will do some tests with alcohol instead of solid fuel, then I will try a new boiler with both fire and water tubes as you have suggested.

[philbutton]

I have made a number of gas-fired single flue vertical boilers of around 3" OD, generally with 'hedgehog' spikes in the firebox to increase the heating surface. I have found a simple trick to help prevent too much heat going straight up the flue and that is to make a loose 'ball' of heat resisting wire (hairdrier heating element works well) and insert it in the lower end of the flue. The wire then absorbs the heat from the flame, glows red hot and radiates heat into the boiler instead of wasting it up the flue. With a gas-fired boiler this can give problems with lighting the burner from the top of the flue, but this can be overcome by leaving a 'hole' through or beside the ball. I have not tried it with solid fuel or alcohol.

Keep trying

Phil

[logoman]

that's a clever trick Phil, I'm going to try that on my small meths fueled Hemmens. All I need now is an old hairdryer!

[kno3]

I have made a number of gas-fired single flue vertical boilers of around 3" OD, generally with 'hedgehog' spikes in the firebox to increase the heating surface. ...

What do those spikes look like, do you have a picture?

[cmbellman5]

Looks like I have opened up a great discussion.

I have not done any boiler making since opening this subject, I have been concentration on rebuilding some engines to reduce friction.
I still haven't worked out how to add pictures to these posts

Thanks for all the ideas, I'm reading with interest

[cmbellman5]

I have posted some pics in my album showing my ill fated boiler and engine, also my test rig, fantailed launch..
Could someone explain how I download photos to the forum?

[derekwarner_decoy]

Hi PD's......cmbellman5......give yourself a name so we can all talk

this engine has caused all the boiler grief. It wont run under 30 psi.
I believe I can engineer out friction to get it to run on 20 psi steam

1) an oscillator of such size I believe should start & run [after bedding in] @ say 5 PSI....
2) tell us more of the construction
3) simple checks under load would be to loosen off 'tight points' to determine the root cause of stiction etc

With respect to posting .jpg images with your message......just save your images to your snaps to your PC ....."my documents"....limit them to 1280x960 kb......then go to the ...Additional Options image to the left of the screen here on the PD WEB page & attach them

There are a number of very experienced PD steam members here  ....so do your trials & post the results or questions.........Derek

[cmbellman5]

Thanks Derek, my name is Peter.

Part of the problem with the engine stems from a number of dimensional errors on the design drawing. I picke up most of them as I went along, but the centre heights of the cylinder blocks were incorrect with the pivot point heights and I didn't notice until after attempted assembly and blamed my poor machining.
I re cut the pivot points so the engine ran, then found the crank journal centres were out on the drawing by 1/16". Much filing later the engine ran better. Engine mark two is nearly ready, all dimensional errors I believe have been found.
There is nothing unusual about the engine, bronze cylinders, steel built up crank, bronze bearings, stainless conrods, rest brass.
Engine mark2 has a one piece crank.
here is pic of "stiff" engine

[cmbellman5]

Looks like picture didn't attach, I think I need a more detailed "how to " description.

[Eddy Matthews]

Looks like picture didn't attach, I think I need a more detailed "how to " description.

It's easy, honest, would I lie to you? 

When your posting your message, at the bottom left of the screen you will see an option that says "Additional Options", click on that..... Then you'll see a box that says "Attach", with a Browse button immediately after it, click on "Browse" - A window will open that allows you to locate the file on your computer, just click on the file.

Then when you press "Save" to finish your message, the image will be added to the bottom.

Please note there are limits on the filesize and the number of pixels, so keep the image to a reasonable size - Around 400Kb maximum, and 800x600 resolution.

Hope that helps?

Eddy