The marine engine is the latest model to come off the Mamod production line but it has been a labour of love to get to this stage.
It was an interesting choice to revive the marine engine, which had proved popular in 1940s and 1950s but support and intrigue had dwindled since then. However, recent years have seen an increase in demand and repeated calls for the marine engine to be reintroduced, as modellers looked to move away from the traditional railways and back on to the water.
For Mamod it was not just a case of bringing back the original engine, a completely new strategy was required to ensure that the marine engine was a success. So it was a case of heading back to drawing board and planning out a design that would appeal to the company’s customer base that were becoming increasingly nautical.
Although it may be stating the obvious, the way a marine model is designed is much different from one that can be used on land. Mamod needed to choose materials that were not prone to react with the water. The company opted for brass and stainless steel as opposed to just normal steel as that is too reactive to water.
Focus on remote control
One of the key selling points Mamod wanted to create was a remote control. Engineers determined that the model could prove more successful if collectors could drive their boat on open water, without the need to be good swimmers to simply retrieve it. The remote control posed another challenge to the design of the model and the engine needed to be adapted to fit the common type of servos.
Designing the engine
Once it had been determined what materials to use and how to integrate the remote control function, Mamod engineers then went about designing the marine engine itself. One of the main factors was the prop shaft and how it would be attached. Should the engine be installed horizontally it would require a traverse attachment whereas vertically means the prop shaft needs to go backwards and out the stern.
The former is the most preferable way of constructing a boat engine but it is not widely used. The main concern of the designers was ensuring the crank shaft was as low as possible, if this is achieved then the prop shaft will not need to be angled in order to reach the water and avoid a loss of efficiency.
Mamod to chose to build a much thicker crank shaft than standard models to compensate for the lack of a fly wheel. A bigger cylinder was introduced which ensured more steam could pass through and therefore generate more power. However, to offset this Mamod needed to use a vertical boiler which is much more efficient at reheating coils.
As engineers were aware of the importance of the hull, the base plate of the marine engine needed to be narrow so it could fit. This was an arduous process with a series of redesigns of the configuration of the components.
However, this intensive labour of love eventually bore fruit when Mamod was finally able to unveil the finished product.