I am not a fan of vertical fire-tube boilers, they look “wrong” to me sticking out of the hull like an afterthought, and this is compounded by their less than efficient design. I have built small ones at home as test boilers, and in that scale they can be fierce steam raisers – but I have always liked the Yarrow-style water-tube designs, and fancy making one.
Given the choice of engine this actually seems to become a “requirement” as the engine is listed as consuming 390lbs/hr of steam, and that sounds like somewhere between 40sqft and 80sqft of heated surface and that would be tough to do in a normal barrel-shaped kettle!
So my current choice is the larger of the two SBA Services WTB3 boilers, which provides 63.7sqft of heated surface, so it should provide a little more than the requisite 390lbs/hr if forced, and somewhat less if relaxed.
Having met up with some of the SBA members at Beale Park they made some suggestions and set some ideas running… They suggested I looked at the boilers of John King (which I will) and looking at Nick Powel’s SL Puffin (and chatting with Nick) I was impressed with its neat liquid-fueled Babcock boiler, I can see the attraction of liquid fuel (notably the absence of muck!)
I am attracted to the idea of compound engines, and certainly interested in something which would tolerate some hard work. Having looked around there seemed to be a dearth UK designs for home construction, but I had noticed that Camden Steam were listing a 3″ & 5″ by 3″ compound available as castings by A A Leak.
So I ordered the builders guide, and then in researching people’s experience of the design was offered an almost complete (and almost untouched) set of castings from a gentleman in France – that coupled with good reviews from the forum, and a conversation with Geoff Harrison (who has one of the larger Leak designs in his narrow boat Tixall), sealed the deal.
The Castings are ordered!
If you want to see one of these engines completed to an unbelievable standard with every conceivable auxiliary then take a look at this one
I intend to run the engine condensing, (sea water and boilers not being a good match for each other), and intend to build the in-board condenser (keel condenser involving nasty drag, and holes below the waterline, and something else to damage when trailering!).
While injectors aways seem the right idea, they hate hot water, and can be temperamental, so on the loco I also added a donkey pump, and intend to do the same on the Boat. One of the Southworth Boiler Pumps (vertical or duplex).
We also need to include an electrical system (12v I think using car alternator) allthough a cross-head driven reciprocating generator might be interesting (like those provided for low-maintanenace use in developing countries.)