Naphtha launch

They were a particularly American design, brought into being by a local law that made it impractical to use a steam launch for private use.

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.

The first naphtha launch appears to have been British, reported in the French journal La Nature in 1888.

Naphtha launches appeared in the finest circles, in the best yacht clubs[9] and under the ownership of some celebrated names.

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.

[5] A prominent tube and funnel on the front of the boiler casing (sometimes mistaken for a whistle) is the air inlet.

[13] Lubrication of the engine was performed by the fuel itself, collected in a sealed wet sump arrangement beneath the crankcase.

[5] External water-cooled condensers were used, simple pipes run under the hull, along the length of the keel.

One of the attractive features that first led inventors to consider naphtha as a working fluid was its low boiling point, compared to water.

[14] An earlier use of low boiling point fluids had been Du Tremblay's ether engine of the 1850s.

Waste heat rejected through the condenser of the steam engine was used to boil ether and drive a second cylinder.

Willard of Chicago was more akin to an internal combustion gas engine with timed spark ignition.

Despite the obvious hazards and occasional reports of fires,[17][v] the naphtha launch appears to have worked reasonably well and safely.