Trials have been made at Havre with an electric launch built to the
order of the French government by the Forges et Chantiers de la
Mediterranée. The vessel, which has rather full lines, measures 28 ft.
between perpendiculars and 9 ft. beam, and is 5 tons register.
The electromotor is the invention of Captain Krebs, who is already
well known on account of his experiments in connection with navigable
balloons, and of M. De Zédé, naval architect. The propeller shaft is
not directly coupled with the spindle of the motor, but is geared to
it by spur wheels in the ratio of 1 to 3, in order to allow of the
employment of a light high-speed motor. The latter makes 850
revolutions per minute, and develops 12 horse power when driving the
screw at 280 revolutions. Current is supplied by a new type of
accumulators made by Messrs. Commelin & Desmazures. One hundred and
thirty two of these accumulators are fitted in the bottom of the boat,
the total weight being about 2 tons.
In ordering this boat the French government stipulated a speed of 6
knots to be maintained during three hours with an expenditure of 10
horse power. The result of the trials gave a speed of 6½ knots during
five hours with 12 horse power, and sufficient charge was left in the
accumulators to allow the boat to travel on the following day for four
hours. This performance is exceedingly good, since it shows that one
horse power hour has been obtained with less than 60 lb. of total
weight of battery.
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