Naphtha launch

By the 1880s, the small steam engine was well established as a power unit for small steam launches, as well as for large boats. However US law, prompted by some past boiler explosions, required that all steam boats carry a licensed engineer at all times. Although this was no difficulty for a commercial craft, it prevented small steam launches from being used for personal and recreational purposes. Becoming such an engineer required an apprenticeship of two years beforehand. One of the few amateurs to achieve this and to become their own engineer was Rosamund Burgess, wife of boat designer Starling Burgess. A more popular alternative to the steam launch was the naphtha launch, which used an alternative power source. Advertisements of the period used the deliberate phrase, "Every Man His own Engineer!" to highlight this legal restriction. Origins The first naphtha launch appears to have been British, reported in the French journal La Nature in 1888. This launch, Zephyr, was the invention of Alfred Yarrow, a well-known builder of steam launches for some years previously. Similar launches were produced in the same year by the Swiss company Escher Wyss AG. Typical launches The typical naphtha launch was an open launch of around in length. These were pleasure craft intended for use on fine-weather excursions. After all, a commercial boat with a professional crew would not suffer from the regulatory problem that led to their invention. Naphtha launches appeared in the finest circles, in the best yacht clubs and under the ownership of some celebrated names. Surviving examples Few examples survive today. Some sources claim one, others four. • • == Naphtha engine ==

The naphtha engine is an external combustion engine, generally similar to the type of small steam engine already in use for steam launches. The working fluid is naphtha, which unusually is also used as a liquid fuel to power the boiler. Appearance is similar to a steam launch, having a small vertical boiler and vertical cylinders. The burner for a naphtha engine uses naphtha itself, and is similar to that used for steam cars. Although such convenient and self-regulating liquid fuel burners were also used on steam launches, most launches at the time of the naphtha engine's heyday were still using solid fuel. General arrangement To avoid problems of premature condensation, the engine and boiler units were mounted together. Engines were three-cylinder single-acting vertical simple expansion engines, with 120° crankshaft spacing, so as to be self-starting without dead centre problems. Boiler The boilers were of spiral monotube form. These were single-pass 'water-tube' steam generators, where liquid at one end of the tube boiled by the time it reached the end, without any looped circulation. Similar boilers, although with conventional water and steam, were also used for steam cars such as the White. The boiler was mounted directly atop the engine, and encased in a polished brass or copper casing with a short funnel above. The purpose of the funnel was merely to vent fumes above the heads of passengers, rather than to act as a draught to draw the fire. Burner Unlike coal or wood, the jet burners used did not require additional draught. The boiler was fired with a pressure jet burner, a small quantity of pressurised naphtha being tapped off from the boiler. Engine Lubrication of the engine was performed by the fuel itself, collected in a sealed wet sump arrangement beneath the crankcase. The naphtha fuel was an acceptable lubricant and this avoided the problem of separating lubricating oil from condensed fuel vapour leaking past the piston ring seals. It did however require careful sealing of the crankcase. 'Simplex' engine The "Simplex Naptha engine" built by Chas. Willard of Chicago was more akin to an internal combustion gas engine with timed spark ignition. It is outside the scope of this article. Hazards and explosions Despite the obvious hazards and occasional reports of fires, the naphtha launch appears to have worked reasonably well and safely. Models The naphtha engine is not well known amongst model engineers, but at least one detailed reproduction has been constructed. == In popular culture ==

In the 1921 novel of the popular Tom Swift series, Tom Swift Among the Fire Fighters, the hero rescues passengers with the aid of a naphtha launch, describing it as "old-fashioned". The author also passes comment as to them being "a trifle treacherous" to light. == Naphthalene locomotive ==

A railway locomotive using solid naphthalene was built by Schneider-Creusot in France in 1913. This had no relation to the naphtha engine. It was a 70 bhp internal combustion engine, similar to a petrol-paraffin engine, which operated as a petrol engine and once started and warmed up could be switched to naphthalene simply as a cheaper fuel. The naphthalene was melted and vaporised by a water jacket, heated by the engine. == See also ==