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[rweust]

Beginning 2009 I decided to build a model of a harbor tug with live steam propulsion. This got a bit out of hand after a question from my kid about steam engines (How do  they work, what do they do?). The toy models they sell in shops were to tinny for me.

I looked for a nice steam engine kit first and found the PM Research Marine Twin Engine with the vertical boiler Nr. 1 (also a kit from PMR). I found the following tug to build this engine in and asked the Dutch NVM (model builders association) for drawings of this Amsterdam harbor tug "President Roosevelt" (in function directly after WW2).



The drawings lacked some detail, so looking on the internet provided me with more usefull information. I had to make a few assumptions though. I'm afraid I'm not a historical model builder. I started with the steam engine and boiler (and not even a triple expansion nor a Scottish boiler) and looked after this for a tug to fit it in. In fact this is my first model. During the building process it began to become clear to me that this will end in a very nice model with practically no plastic on it. So I decided to let the wood and metal show themselves. The very robust steam engine and boiler from PMR are also worth showing. This resulted in the following model of 93 cm, scale 1:35.



They hull is made from scratch the conventional way. The frame is made of plywood, the flat, box construction keel is filled with lead, the hull plated with 2,5 mm balsawood and covered with glass and epoxy. The flat keel made it possible to place an aluminium mounting plate at the bottom in the bout to mount the boiler and steam engine as low as possible.



The Twin Marine Engine from PMR has 2 double operating cylinders with a 1/2" bore and 3/4" stroke. The boiler Nr.1 is a vertical smoke pipe boiler 3" wide,  7" high and has a working pressure of 50 PSI (app. 3 bar).



In the front I placed a water tank with a hand pump to (re)fill the boiler. Refilling is necessary about every 10 minutes, as poking up the fire (4 Esbit blocks).



Furthermore this model has an operating search light (not really original, but fun), a working steam whistle, interior lighting, deck light and navigation lights.



All the hatches and doors can be opened to provide the fire with enough oxygen. The draft from the vertical boiler does not need them all to be opened though.



Operated is this model with a Spektrum receiver and transmitter (DX5e).



The Becker rudder makes short turns possible (I really need this, due to the size of my pond).

[rweust]

The boiler is filled, the fire is lit (4x Esbit block).



The tug runs excellent with the four bladed screw (55 mm) and Twin Marine Engine. It will go about 5 km/h (look at the wave form).



Short turns are possible, will cost full steam though.



Search light on.



Navigation lights on.



This is great fun, I can recommend it.

[rweust]

The following URL will show you the Youtube movie I placed (made by my son):

http://www.youtube.com/watch?v=Ei8xU3eMYFA

Searching for the Dutch words "Stoomsleper" or "Havelsleepboot op stoom" will also do the trick.

Watch the steam outlet from the cylinders I placed in the chimney.

Have fun.

[Tug-Kenny RIP]

Very impressive. Well done. Now you have got me interested in trying this   

Great film. 


ken

[Bernhard]

    Great Tug......ver good looking .....Great Job... how long working time do you get,,,and will you go to gas?........

Regards Bernhard

[kiwimodeller]

Looks great Robert, very nicely done. I would suggest that you experiment with a larger propellor. A larger prop would slow the engine and mean you would use less steam so you should get longer runs. I have sold several of these engines and fitted one for a friend in a 44" (1.15m) hull. All the ones I have seen running are turning a 70 to 75mm prop very easily and the engine is just ticking over slowly and smoothly and lasting 20 to 30 minutes on one fill of the boiler. Hope this helps, Ian.

[rweust]

Thank you for your kind replies,

I build this model in less than a year. The boiler and steam engine were kits and easy to assemble. In Holland this is not a very popular steam engine (strangely enough) and the guy I bought it from in the US, couldn't give me information about the diameter and kind of prop that would fit this engine. As you can see on the wave form on this tug on full speed, the Twin Marine Engine from PMR can easily power a longer vessel. I totally agree this engine can drive a larger prop. It's an engine with great torque even at lower rpm and runs very smoothly. At full speed it will run about 400 till 500 rpm in my case. Lowering the rpm will of course save steam.

For me the refilling of the boiler is not a problem, I run it mainly in my pond behind the house. The short turns with the Becker rudder require full steam, so that's probably why the boiler runs half empty every 10 minutes.  As a show model (still in the living room, as long as I dust it, the wive agrees) a larger prop would also be a bit out of proportion.

I don't think I will refit this tug with propane/butane mix gas. As clean as it burns and easy gas is to regulate, I really do like the more realistic smoke from the Esbit. I realise it's not coal, but still gives me the idea you're still controlling the fire yourself. As maybe more grownups, I don't mind to poke around in a real fire. Coal is of course the ultimate, but does take to many cleaning after each run (in this model this would take some dismantling), so Esbit is a nice in between solution for me.

Call me crazy, but I'm really thinking about building an automatic re-filler for Esbit fires, by using a PIC micro controller that measures steam and exhaust temperature. Are there more of these idiots who have this sort of ideas, or has it been done already?

[KBIO]

 :-)Very nice tug and beautiful building! Congratulations!
This PM engine is about +/- 9.3cc if I remember. It works pretty good but is maybe a bit greedy for your boiler. :embarrassed:is the pressure setady while sailing??
Are there more of these idiots who have this sort of ideas, or has it been done already? Fortunatly: yes! 
I've seen one feeded with an endless screw. I cannot tell about its efficiency though!
Regards! 

[kno3]

Congratulations, it's a wonderfully made tugboat. The steam plant looks very nice and well organised too. It would be really cool if you could build an automatic Esbit feeder, I shall watch this closely.
The way you arranged the engine and boiler is very similar to my first engine in my steam tug (a Wilesco D49) which I hid the same way under the cabin.

[Barnacle Bill]

Hello!
I am a new member to this Forum, and am gradually finding my way through the veritable treasure trove of material posted here. This evening I chanced upon your posting of your steam tug. I felt I had to send you a post. What an utter delight to see such a beautifully designed and executed model. My congratulations to you and your son for reaching a standard of excellence seldom seen in model making.
I am currently trying to come to terms with a whole lot of things that I need to know in this field. To see amodel such as yours is the reason why I keep reading and learning.
Thankyou for sharing it with the Forum.
Barbacle Bill
Canberra, Australia

[Bernhard]

THATS A SUper fine Tug........i like the ide with boiler and engine,,,,,TIP-TOP

Regards Bernhard

[Norseman]

I'm really thinking about building an automatic re-filler for Esbit fires, by using a PIC micro
controller that measures steam and exhaust temperature. Are there more of these idiots who
have this sort of ideas

Hi

It's  really nice model all round and I like the rudder set up.
I know nothing about steam but a friend has made me
steam curious recently.

Re the automatic filler - that is a great idea. I hope you
make your own design and post it up here.

Dave

[rweust]

I will try the bigger propeller as advised to reduce steam consumption. A 70mm type just fits (see pictures). I will let you know tomorrow. I'm a bit worried about the contra-torque it will create when changing throttle, as the PM Twin Marine Engine # 8 is very direct => wobbling, but the test tomorrow shall give the result.

Robert.

[kiwimodeller]

Hi Robert, I will be very interested to hear how much difference in running time the new propellor makes. The other possibility which you could try is a prop which has more pitch than the diameter. Yould could maybe run a four blade prop of perhaps 65mm diameter and 100mm pitch. That would load your engine up well. My understanding is that such props are specially made for steam powered boats by the Prop Shop in England. Best of luck with your test, Ian.

[rweust]

Hello Kiwimodeller,

Steam consumption has reduced a bit, but not to much, I estimate about 20%. Still have to refill the boiler every 10-15 minutes. It's not a big problem and I leave it this way.
The pitch is already relatively big with this four blade screw. I don't expect much improvement in steam consumption of that.

The speed of the model has improved with the 70mm four blade propeller, as certainly has the acceleration, this with more than 20%. As you can see in the video it is a bit to fast for handling in my pond now.
The wobbling I was afraid off due to the contra-torque of the bigger prop, doesn't really occur when changing throttle.

As you concluded correctly the PM Research #8 Twin Marine Engine can drive a larger prop and has absolutely no problem with this 70mm four blade at 2 till 3 bar (50 PSI) steam pressure.

http://www.youtube.com/watch?v=72SzDbFVo2Y

 

[rweust]

I'm sorry Kiwimodeller and others,

I made a small mistake. The new prop has a diameter of 65 mm and a pitch of 67 mm. It's a Raboesch type A, four blade propeller.

I had it lying around for a while, in my head the size changed to 70 mm.

Robert.

 

[kiwimodeller]

Hi Robert, a very impressive performance in the video and as you say, more than enough power for your small pond. If you have the chance to try it in a larger lake then perhaps a Prop Shop prop which has pitch of 1.5 x diameter would be useful. Watching how she sails in the video it looks also as if you could add a little more ballast to increase the stability. Have you tried this? Regards, Ian

[rweust]

Hi Ian,

Thank you for your advice. The bottom of the boat is absolutely filled with lead under the aluminum mounting plate, so there is no room left. The model is already deep in the water. It's also a shame to make an outside keel, because of the looks an de the very handy flat bottom it has now. The little rolling (wobbling) it shows is a result of the high placed vertical boiler, the flat bottom and the big prop (contra-torque when changing throttle). It's not really unstable, I think I leave it this way.

I don't think I change the pitch of the prop any further, as it now sails great. The engine has still enough torque left to drive a small water pump, maybe I will add this.

Robert.

 

[steam up]

Looks great to me ,might be a problem in choppy water but who wants to be standing at the pond side in conditions like that?
Love the video links.

[KNO3]

What about that automatic esbit feeder? Have you thought how to design it?