Hi George and the others
Thanks for these replies, comments and advice. It's nice to hear from those who've actually built the Borderer engine and have had experience of running it in a model boat. I'm virtually convinced now that it's the Borderer for me.
What size boiler and burner would you recommend remembering that in my application it has to be a horizontal boiler?
I've never really considered building it from stock materials. I'll have to look at my "stores" and scrap box and see what I could utilise from the castings I have for the Marcher as I think some were originally for the Borderer. I don't know yet but I might just take the plunge and sell my Marcher castings and put the money towards the Borderer.
Just out of curiosity and I know the answer could be "How long is piece of string?" but have you got any idea how many hours it took to build the Borderer - it looks really nice and hope mine could turn out as well.
It's interesting that everybody replying to this steam query appear to be model boaters first and interested in steam second. Some of the boats are outsatnding with the woodwork. If one goes to a model engineeering exhibition the engineers tend to see the boat as puely a vehicle for their steam engine and scale and the quality of the boat are secondary.
Thanks again for the interest. It might help others as well as to type and size of engine required for a given size of model. It's difficult enough deciding on an electric motor and voltage etc let alone the complications of steam.
Les
Les,
I would suggest that you make your boiler to a minimum of 4" o/d x 5" to 6" between end plates and make it a horizontal Scotch return flue with a torch type burner and make the engine driven boiler feed pump , this set up will keep you in steam all day.
I have a copy of the boiler that is in Mick's ( Patternmaker ) WIDE AWAKE thread. and I also have the drawings for the Borderer engine which would have to be copied, I can have that done, may be able to help you with a piece of 4.25" O/D copper tube.
Some pics of a Scotch return flue boiler.



If you want to build the engine from stock, BLACKGATES keep a good stock of Mehanite grade cast iron in square and rectangular sizes at reasonable cost and it machines beautifully.
You could make the cylinder head from this remembering to add on for the steel upright lugs and buy some cast for the steam chest and covers.
I made my cylinder head from a piece of square window sash weight and it was absolutely rubbish, didn't know about BLACKGATES at the time.
You wouldn't need to have lagging on the cylinder head just machine it straight.
Hope this helps.
George.
P.S. Should have told you that I am one of those guys that don't build beautiful models, I have only built 2- steam powered model but have lost count of the number of engines and boilers.