whats the Hemmens like, I am thinking of putting one in a 40 inch solent launch from Metcalfe mouldings.
Andy Wright
The Hemmens engine is a robust, compact and relatively powerfull engine. The "V" configuration was perfect for me as I wanted to get the engine into a very small space to enable the boiler flue to be as close to below the funnel as possible.
I have had some very impressive speeds from my steamer with a Richmond engine pushing about 35lbs of very blunt hull at a very deep draught through the water. It is responsive, smooth, controls nicely down to a very low presure and revs and reverses reliably. The construction is simple and neat and a nice little water pump can be fitted if you want.
Down sides are oscillators do use quite a bit of steam but only if you are hammering it around too much. Stick to scale speeds and it wont be a problem. I would rather the cylinder covers were fastened with screws rather than being a tight interference fit and mine has been back to John Hemmens twice to rectify leakage at the control valve face. Since it was refurbished last time I have not steamed it so I cannot say whether the attention it recieved has resolved the leaks but there is always going to be a degree of leakage at a face to face lapped contact. I remain unconvinced that a brass to aluminium joint face is the best combination but John Hemmens assures me that it will work well if set up correctly.
Leakage at this face is not as big an issue in a launch as it is in an enclosed hull anyway so it should not prove to be too much of an issue for you.
Bottom line I think it is a great little engine and will push a 40" launch around very easily.
