# Penbwl a Welsh tadpole



## Tony Bird

Hi,

It is some time since I posted anything in HMEM, for the last couple of months I have been making a copy of a model steam powered boat described in the August 1933 edition of Popular Mechanics.  I have to say that it isn't the prettiest boat that I have built but it does have a certain ugly charm.  Known as Polly Wog which I believe is American slang for tadpole the designer isn't credited in PM.  On the net I found a 1939 catalogue of a company name Boucher that was marketing both a finished boat and a kit to build a Polly Wog.  I wonder if they got the design from PM?  It would be interesting to know.

The build started because a member of the Mamod Forum to which I belong to, posted the plans and text for Polly Wog which he had found re-published in a Live Steam magazine.

I was looking for something different to make and Polly Wog is different!  A steam outboard motor, a boiler consisting of three tubes joined at each of their ends and a twin rudder in front of the propeller.

Some of the materials suggested were a little bit of a problem to obtain in South Wales:  Orange boxes for the hull bottom, aluminium stovepipe for the deck, bevelled gears from a radio tuning condencer for the right angle drive of the engine and a slip tee for the gear box housing being particulary difficult to sourse. 

The boiler is heated using Sterno and produces enough heat to power the engine easily.  It has been tested in a tank and seems to work well.  A safety valve has been fitted instead of just a filling plug as suggested.  Rudder only R/C is fitted.  Unfortunately our local lake is weed bound until the winter kicks in when it dies back, so it will be some time before it can be tested.

A direct translation of Penbwl, pronounced Pen as in ink and Bull as in cow, is flat head and is used in Welsh for Tadpole.  Why Tadpole as well?  If you have visited Wales virtually everything is in both English and Welsh.  It seemed a shame not to do the same also there were enough letters on the sheet of transfers to do it.  The other side has Polly Wog on it just in case she goes to the States, I would hate a language problem.

I did take some photographs of the construct techniques if anyone is interested, which I could post retrospectively.

Regards Tony.


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## compspecial

Very interesting, Tony..please tell us more!
Stew


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## Brian Rupnow

Very nice!!! I see you are using twin wobblers for a motor drive. a lot of folks on here would appreciate plans for that engine.--Very nice and unique project.---Brian


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## dsquire

Tony

I don't care if it is a Penbwl or a Tadpole, it still is a very nice boat. I can well imagine that you would have had a hard time finding Orange crates to use. My sister still has 2 of them from when we were kids. We used them as bedside tables when we were kids. I think that I would have a hard time if I were to try and use one to build a Tadpole. 

We definitely would like to see some more photos and details on how you built the boat as well as the engine details. Perhaps you could re post the plans if it doesn't violate copy-rite or post a link to them.

Thanks for showing this to us.

Cheers 

Don


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## Brian Rupnow

DSquire--It must have been a Canadian thing. All the beds in the house I grew up in had orange crates stood on end as night tables beside the bed. My mother had sewn fancy slipcovers for them. they even came with a built in divider that acted as a shelf.---Brian


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## Tin Falcon

http://books.google.com/books?id=7OEDAAAAMBAJ&q=todpole#v=onepage&q=Polly%20wog&f=false
tin


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## dsquire

Brian Rupnow said:


> DSquire--It must have been a Canadian thing. All the beds in the house I grew up in had orange crates stood on end as night tables beside the bed. My mother had sewn fancy slipcovers for them. they even came with a built in divider that acted as a shelf.---Brian



Brian

It was the same in our house. Mother or Grandmother had made nice slip-covers for them. If I remember correctly mine had Cowboys and Indians on them.

Cheers 

Don


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## dsquire

Tin Falcon said:


> http://books.google.com/books?id=7OEDAAAAMBAJ&q=todpole#v=onepage&q=Polly wog&f=false
> tin



Thanks

Cheers 

Don


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## Tony Bird

Hi,

http://books.google.com/books?id=7OEDAAAAMBAJ&q=todpole#v=onepage&q=Polly%  20wog&f=false

Yes that is the original article from Popular Mechanics.  My copy came from the October 1981 edition of Live Steam which is identical to the original article.

If anyone is thinking of making the boiler or engine it will need drawing out as there are anomalies in the dimentions.  I will see if I can make sense of the sketches that I did and post them along with some constructional photograghs.

Regards Tony.


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## Tony Bird

Hi,

Some photographs of the construction of Polly Wog's Hull.  Steaming hull sides, bending hull bottom and finished hull.

Regards Tony.


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## Tony Bird

Hi,

Some photographs of deck, air intakes and rudder

Regards Tony.


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## Tony Bird

Hi,

A start was made on the engine. First a drawing was made based on information from the Polly Wog article. The engine was made using the suggested materials including copper cylinders!

Regards Tony.


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## dsquire

Tony

Very nice work there. I'm keeping an eye on it. 

Cheers 

Don


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## ProdEng

An unusual and attractive project, thanks for sharing.


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## Tony Bird

Hello again,

Still sorting photographs must use a better system!  Propeller gear box assembly.

Propeller next if I can sort the photographs out.

Regards Tony.


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## Tony Bird

Hi,

Sorted the propeller photographs out.

Regards Tony.


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## nemoc

Tony,  It looks pretty to me.  Outstanding workmanship!  You did a great job with the sheet metal.  Thanks for the photos.

Craig


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## larry1

Great work,I think that the boat looks great.    larry


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## robcas631

That's cool!


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## Tony Bird

Hi,

Next the boiler and flame guard where made.

Regards Tony.


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## Tony Bird

Hello again,

Final straight model to date.  Video of test run in tank/storage box at:

http://s895.photobucket.com/albums/ac154/gaynorandtony/Polly Wog/?action=view&current=MVI_1574.mp4

Need for the weed to clear in local lake when it gets cold before a proper test.  Had a bit of an issue with paint reaction.

Regards Tony.


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## Brian Rupnow

That is just excellent craftsmanship!!! I love it.---Brian


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## Tony Bird

Hi,

A water line has been added and the transfers varnished over so Polly Wog, Penbwl or Tadpole call her what you wish is now completely finished and ready to go!  Well when the weed dies back in the local lake it can be tried out.

It has been an interesting build, I think it is heavier than the Boucher commercial version with its brass cylinders, flywheel, gear box and R/C equipement against the Bouchers aluminuim bits and no R/C.  The article in Popular Mechanics promised 6mph for nearly a mile which means that it should only run for 9/10 minutes, we shall see, in the Boucher catalogue a run of 20 minutes (nearly 2 miles?) is claimed for their product.  A new deeper tray for the Sterno has been made, if it doesn't run long enough I might fit a ceramic burner.  If I do get it to the lake I will try and post a video of her performance.

Regards Tony.


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## Tony Bird

Hi,

Polly Wogs first Sailing. 
Thursday 4th.October 2012.​ 
We enjoyed the two weeks holiday meeting friends andplaying trains on the flat lands of the Netherlands but it is nice to get backto the hills and mountains of Wales.

Polly Wog was taken away with us in the trailer along with the railway layout, the intention being to give her her first sailwhile in the Netherlands.  Alas thoughthere was certainly enough water and the weather was fine the high winds precluded any chance any of Polly Wog taking to the water.  We left the Netherlands and spent the last few days away travelling through Belgium to the ferry that would take us home from France.  So it was getting to look if Polly Wog wasnt going to get her first sailing in mainland Europe just a1000-mile trip in a trailer!  We arrived with our camper van along with its trailer and camped on the dockside in Calais ready for an early morning crossing to Dover in the next day.

While playing trains in the Netherlands our friends Elinor and Nick who after a holiday of some weeks in the Hartz Mountains of Germany came to help run our railway on their way home joined us.  They were with us camping on the dockside before returning home to the UK via the tunnel. While walking on the front in Calais Nick and I passed a childrensamusement park at the top of  the beach. The park looked closed for the winter but a large portable pool was still full of water!

So Polly Wog was removed from the trailer R/Cbatteries fitted, her engine oiler up, fuel tray filled with Sterno and with water in her boiler she was taken to the pool. The pool was ideal its high sides protecting the water from very highwinds.  First a bit of a problem the gas lighterwas empty!  So a Tabac to get some form of ignition had to be found.

Having fired up the Sterno dispite cold high winds Polly Wog was soon making steam and was placed in the water.

How did she perform? Well she is quite fast giving her shape and weight.  Alas the R/C rudder has very little control.  The first very short video shows her first run in open water.  The large propeller torque and a flat bottom turned her with the rudder in line with the hull, so some time was spent off setting the rudder to compensate for this.  With the rudder off set she travelled in a straight line but with still not a lot of control.  The second short video shows the tuning process, retrospectively it might be better to off set the propeller rather than the rudder to compensate for the torque of the propeller.  The third video shows Nick in control?  By now the Sterno is getting low and speed much reduced.  It was getting cold and twilight was setting in and a meal and drink was needed so Polly Wog will have to wait for a larger rudder to be fitted before her next try in water.  All in all Im quite happy with Polly Wog's performance possibly not as fast as the 6mph claimed but fast enough.

Regards Tony

.


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## The_Paso_Kid

Good Job on the boat Tony. My grandfather came across that same article many years ago and made a few efforts at building that outboard steam engine, with modifications, of course. Instead of building the lower unit he intended on using the lower unit from a small gas model outboard engine. Unfortunately the first engine he made he used the same bore size as the plans and the engine could not generate the power necessary to overcome the friction on the cable drive in that lower unit. So he built another with a larger bore size. We eventually built a third outboard engine using a single cylinder and piston type valve. See photos.


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## Tony Bird

Hi,

*Good Job on the boat Tony. My grandfather came across that same article many years ago and made a few efforts at building that outboard steam engine, with modifications, of course. Instead of building the lower unit he intended on using the lower unit from a small gas model outboard engine. Unfortunately the first engine he made he used the same bore size as the plans and the engine could not generate the power necessary to overcome the friction on the cable drive in that lower unit. So he built another with a larger bore size. We eventually built a third outboard engine using a single cylinder and piston type valve. See photos.
*
Interesting ideas. I particularly like the piston valve one.

Regards Tony.


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## Tony Bird

Hi,

Today I ran Polly Wog to see how long and fast she who go the results were 1.125 mph for twenty five minutes.

A video at:



Regards Tony.


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## bazmak

Metal workmanship is top class as usual Tony and it seems so is your woodworking skills
Photographic details and descriptive thread are also excerlent as usual.Love following your threads
Please keep it up.As a matter of interest what is the overall length of Tadpole


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## Tony Bird

Hi,

As a matter of interest what is the overall length of Tadpole?

23" the original plans came from Popular Mechanics

http://books.google.com/books?id=7OEDAAAAMBAJ&q=todpole#v=onepage&q=Polly% 20wog&f=false


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## Cymro77

Tony,
Pretty darned cool.  You are quite the craftsman, your horologic skills are showing.  You have such great fun with your skills!  Glad to see you on HMEM again.


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## Brian Rupnow

Tony--I do like your outboard motor.---Brian


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## gmaf

Tony,
Thought you might like to see my version of the Polly Wog engine.
Regards,
George


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## Tony Bird

Hi George,

I like your engine, a much better finish than mine.  The propeller looks smaller than the 2" fitted to mine does it perform well in water?  

Regards Tony.


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## gmaf

Thanks,Tony
Haven't run mine in water yet. I need to build a boat!  It runs fine except for some vibration. Haven't figured out how to balance the flywheel yet.
Does yours vibrate much?
George


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## Rocket

Hi Tony, Love the Tadpole. Great work on the engine. Thank you for showing us your work. Rocket


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## Tony Bird

gmaf said:


> Thanks,Tony
> Haven't run mine in water yet. I need to build a boat!  It runs fine except for some vibration. Haven't figured out how to balance the flywheel yet.
> Does yours vibrate much?
> 
> Hi George,
> No real vibration as you can see in the video when running free.  You will probably find that when it is in water and running a lot slower the vibration will disappear.  It might be that your cylinders and piston are heavier than mine maybe a hollow piston and aluminium big ends make a difference?
> Regards Tony
> George


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## werowance

very very nice.  it looks like the engine/drive could be adapted to a servo to be steering mechanisim eliminating the need for a rudder? would that be possible


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## Tony Bird

Hi,

Very very nice. it looks like the engine/drive could be adapted to a servo to be steering mechanism eliminating the need for a rudder? Would that be possible?

Yes but only before the engine was built.  It would be too difficult to modify the existing engine.

Regards Tony.


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## Ed

The_Paso_Kid said:


> Good Job on the boat Tony. My grandfather came across that same article many years ago and made a few efforts at building that outboard steam engine, with modifications, of course. Instead of building the lower unit he intended on using the lower unit from a small gas model outboard engine. Unfortunately the first engine he made he used the same bore size as the plans and the engine could not generate the power necessary to overcome the friction on the cable drive in that lower unit. So he built another with a larger bore size. We eventually built a third outboard engine using a single cylinder and piston type valve. See photos.
> 
> View attachment 85504
> 
> 
> View attachment 85505
> 
> 
> View attachment 85506


Where did you get the gears? I'm at the point where I need the gears to go no with my build. Thank you Ed


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## Ed

I'm still looking for gears. I started to make them.Whats the number of teeth are on the gears?


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## gmaf

Brass slot car gears worked for me. There are many different ratios of bevel gears available.


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## olympic

Slot car gears worked for me  too. Mine have a 3:1 reduction ratio, but then I'm not out to beat the Spirit of Australia.


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