The Steamboating Forum

Having just purchased a 2 drum water tube steam boiler for my Selway Fisher 15ft Rose project, I am now on the lookout for a suitable engine.
I have been considering something along the lines of a Stuart 5a complete with a Stephenson's link.
As my proposed specification includes a keel condenser, what other considerations should I be taking into account e.g. water feed pumps etc ?
Many thanks
Ian

ianrichards wrote:Having just purchased a 2 drum water tube steam boiler for my Selway Fisher 15ft Rose project, I am now on the lookout for a suitable engine.
I have been considering something along the lines of a Stuart 5a complete with a Stephenson's link.
As my proposed specification includes a keel condenser, what other considerations should I be taking into account e.g. water feed pumps etc ?
Many thanks
Ian

A 5A would certainly be a reasonable engine: try to get one with a full set of oil-cup lubricators or similar. For insurance purposes in the UK you'll need two independent boiler feed systems, probably an engine driven mechanical pump, plus a hand pump. You could try a steam injector, but they're very fickle things when as small as that, and I wouldn't go that way myself: try one by all means. On this scale condensing will be more for water re-use than efficiency, so there's not much point in an air pump.

Thanks for that
Just the sort of info I needed

RGSP wrote:

ianrichards wrote:Having just purchased a 2 drum water tube steam boiler for my Selway Fisher 15ft Rose project, I am now on the lookout for a suitable engine.
I have been considering something along the lines of a Stuart 5a complete with a Stephenson's link.
As my proposed specification includes a keel condenser, what other considerations should I be taking into account e.g. water feed pumps etc ?
Many thanks
Ian

A 5A would certainly be a reasonable engine: try to get one with a full set of oil-cup lubricators or similar. For insurance purposes in the UK you'll need two independent boiler feed systems, probably an engine driven mechanical pump, plus a hand pump. You could try a steam injector, but they're very fickle things when as small as that, and I wouldn't go that way myself: try one by all means. On this scale condensing will be more for water re-use than efficiency, so there's not much point in an air pump.

How many oil cup lubricator are there in a full set?
Regarding engine driven mechanical pumps, please excuse the rather dumb question, but are they an independent unit or are the attached to the engine itself?
And finally, for the moment at least, what would the ideal specification for a 5a?
Many thanks
Ian

How many oil cup lubricator are there in a full set? ANS: See attached picture of a Stuart No 1 in a small steamboat, a good example of a reliable engine setup.

Regarding engine driven mechanical pumps, ... are they an independent unit or are the attached to the engine itself? ANS: Some drive a small reciprocating pump directly with an eccentric on the crankshaft, but the high speed of the engine (500 RPM +/-) often results in pump reliability issues. I would use a small toothed belt drive, 2:1 or 3:1 ratio to the feed pump crank. A 10mm wide belt will be strong enough, and efficient.

What would the ideal specification for a 5a? ANS: I do not understand your question? Maybe steam pressure 5 to 7 atmospheres? What specifics are you looking for?