Reversible Marine Engine

Reversible Marine Engine

A friend gave me a set of castings for a small marine steam engine which he had started when he was an apprentice machinist in the early 1970’s but never finished the project. He got side tracked and joined the Australian navy to see the world and became a senior officer. His work involved the commissioning and operation of steam turbines on the navy ships.

The drawings and castings were sold by HobbyCo Pty Ltd, a model supplier in Sydney and is similar to the Trojan engine sold by Reeves. It is a vertical marine engine with a 5/8” bore and 5/8” stroke, fitted with a slip reversing eccentric. Only the steam cylinder and the base had been completed and all other parts had to be made to finish the model.

Castings after machining and grit blasting

Machining slide valve connecting rod

Cylinder bottom end cap and crosshead guides

Crankshaft and Base Assembly

Reversible Marine Engine Part 2

The eccentrics on a standard steam engine with a slide or piston valve are fixed to the crankshaft with a key or clamp screw and the direction can be reversed by rotating them by 180 degrees.

On an engine with slip eccentrics they are not fixed and is free to “slip” on the crankshaft and are driven by a pin on an adjacent boss that is fixed to the crankshaft. Manually turning the crankshaft in the opposite direction moves the pin but it does not contact and drive the eccentric until it has moved thru 180 degrees.

A slip eccentric is one of the easiest ways of making a steam engine reversible and is ideal for use on a small boat.

Assembly of Engine, Painting and a Wooden Base

The boiler for running the engine is a $35 ALDI steam cleaner and much better than running a noisy air compressor.

Link for video on Youtube

https://www.youtube.com/watch?v=ygG549zQDqI

Edited By Paul Lousick on 29/04/2022 04:24:37

Beautiful little engine. Nice work! I love the Aldi steam "boiler" idea too.

Your friend's career in the navy is a great example of what model engineering can lead to in life. I started off making a little oscillating engine with boiler for a high school science class and ended up working on power station steam turbines and industrial boilers. Gone full circle back to the models now.

That turned out well, quite a few similar features to the small marine engines I made last year, they make a good quick fun project.

Lovely

A good project well completed. Thanks for the story and the pictures. Thanks also for the description and cad drawing of how a slip eccentric works, we're never too old to learn are we.

Jim

Nice work. It looks identical to a Reeves 'Trojan', did the old Reeves licence designs to other countries ?

What a great little engine! Nicely built. Cheers Paul

I don't know the history of the original design and castings for the engine or where they were made..

Are AJ Reeves drawings based on those from Stuart Turner or their own ? Or are the HobbyCo drawings and castings supplied by Reeves or based on those by Stuart Turner ? I do not know.

HobbyCo still exists in Australia but is completely re-structured and no longer sell the same models.

Paul

It's a pity that for marine use it won't be self starting

Roy

Although the layout is similar to the Stuart Simplex it is not the same so no relation to the Stuart design.

It's very close to the Trojan which was one of Westbury's designs, the drawings for which can be had from a few sources. The likes of EJ Winter do some of the designs that reeves also sell

There are quite a few "pond bot engines" from the 20 & 30 that all have a the same sort of look to them but all differ slightly, many were available as complete engines as well as part of fully machined kits from the likes of Gamages, Basset lowke, Stuart, Stevens Model Dockyard, etc

Self starting was not an issue at the time as there was no radio control, just set it off from one side of the pond and walk briskly to the other side so you got there before the model, rudder was just a friction affair - set and forget. A popular pastime

Edited By JasonB on 29/04/2022 13:32:44

Very nice.

Originally I was thinking that the slip reversing feature was a good idea for a small full size boat not a model. Something 12-20 foot long.like the one in the movie "The African Queen"

A friend used to have a 16' half cabin boat with a petrol engine that was started not by pulling on a rope around a pulley but by spinning the flywheel by hand. (what I call an old put-put type fishing boat). Turning the flywheel on a steam engine would be much easier and if in the correct position, the engine will self start when the steam is turned on.

Really nice engine build Paul.

Its interesting that other Trojan and its look alikes have appeared recently. I tried to build Trojan without castings when I was at school. I tried again using bar stock about 12 years ago (photos in my album). I was surprised to discover that a casting set is about £100 now!!! The completed simplex, fully machined looks like it was about £3.

Phil H