DIRECT ACTING ENGINES

[kiwimodeller]

Has anybody had any experience (or know of any plans) for engines that connect direct to the shaft of a sternwheeler? I have seen the Westbury plans and others for oscillators that go on to the shaft of a sidewheeler and I guess they would work for a stern wheeler but I have heard that the Westbury engine is not the best thing to build. The originals on the full size boat were two separate cylinders, one each side of the paddlewheel and I beleive they were slide valve with reversing gear. I understand the eccentrics were mounted on the wheel shaft inside the connecting rods. There was also another NZ boat with twin reversable oscillating cylinders connected direct to the wheel. Is there any disadvantage to having engines of relatively small bore but long stroke? I was thinking of perhaps 3/8" bore by 2" stroke. All comments and suggestions welcome. Thanks, Ian.

[Hankwilliams]

Hi,

I 've build two sternwheelers with direct acting engines.

First in the 1990tis the interesting "Zulu" with the oscillating long stroke engine of Krick's "Mark Twain". This the simplest way was to use a direct acting engine. The bore and stroke of this engine is 12 to 60 mm. A Regner flame tube boiler produces sufficient steam and the engine easy is reversibel with a valve.
But the kit of "Mark Twain" with the engine the isn't available since a long time ago.

In 2004/5 I built a slightly bigger sternwheeler "Ville de Bruges" after a scetch in a historic book. This time I used the excellent Regner 12/36 for direct acting to the paddlewheel. The Regner engine is very powerful, she is even availiable as a kit and it's no problem to alter it ( in my case: engine base of aluminium, longer pitmans and correspondending valverods).
Original this engine has a Stephenson reverse, but it's more reliable to use a reverse valve for the altered engine, it's easy, because of piston valves.

With this engine and a larger flame tube boiler the boat is much more powerful and faster than the "Zulu" with her oscillating one.

The hulls of both steamers I made of wood. As Eddy wrote, it's not a great problem. The hulls most sternwheelers are flat and can be built simply with planks on frame. If the hull gets a coat of epoxy with glass fiber in and out you will get a stabil watertight and light casco.

Greetings

Tom

[Hankwilliams]

I want to add: For direct driving the paddlewheel the relation of bore and stroke of the engine should at least be 1 to 3, better 1 to 4 or 5.
If it's not, the engine will be overstrained, the steam consumption is very high and it will run not smooth.

Tom

[steamboatmodel]

Hi Tom,
Any photos of the engines?
Regards,
Gerald.

[mjt60a]

What you need is something like this - http://www.youtube.com/watch?v=p0OmPBQMUXU&feature=channel_page - I have absolutely no idea how to build one though...

*note; from the look of all the moving parts it works in the same way as the real thing, see the diagrams and animations here - http://twaintimes.net/boat/sbpage3a.html

[kiwimodeller]

Thanks for that Tom, I could not see any reason why it would not work but it is nice to know that someone has already done it and it worked fine. I will have a look at the Regner engine but I have an older friend who just loves challenges such as building engines that are different. Does anybody know of plans for this type of engine? Thanks, Ian.

[Brooks]

Here is a set of plans. There is a video of the engine running, looks very nice.

http://www.agelessengines.com/s-boat.htm

http://www.youtube.com/watch?v=p0OmPBQMUXU&feature=related

[kiwimodeller]

Boy, that is what I call an engine, or is it considered two engines? Just shows what can be achieved. I am not looking to go anywhere near that big or complicated but that is still an inspiration. Thanks for the links, Ian.

[malcolmbeak]

Ian
Not exactly plans, but maybe ideas for a suitable challange for your friend.
These illustrations are taken from a reprint of the catalogue of "The Marine Iron Works of Chicago" circa 1908.
ISBN No. 0 948885 00 9
There are lots more illustrations of small sternwheelers and a few of engines and boilers.
Malcolm

[Brooks]

Malcolm, thanks for the book suggestion, I've ordered a copy :-).