Читать книгу The Launch Boys' Cruise in the Deerfoot - Ellis Edward Sylvester - Страница 5

The first time you stepped aboard a motor boat you were impressed by the looks of the engine and the numerous appliances which when rightly handled drive the craft through the water at the rate of ten, fifteen, twenty and sometimes more miles an hour. You thought it would be hard to learn to manage the boat and know how to overcome the different kinds of trouble that are almost certain to arise. But the task, after all, is simple and with patience you can soon master it.

In the first place let us find out the principle which governs the smooth, swift progress of the structure. I shall be as brief and pointed as possible.

As a foundation, we need a good supply of clean, strained gasoline in the tank. Unless the fluid is free from all impurities it is likely to clog and interfere with the working of the machinery. The tank is so placed that its elevation is sufficient to cause the gasoline to flow by gravity through the pipe, which is connected by an automatic valve with the carburettor, admitting just enough to answer the purpose desired. As the gasoline is sprayed into the carburettor a quantity of air is drawn in from the outside. The two mingle and form a highly explosive gas. To start, you give the fly-wheel a rapid swing, which causes the piston to move downward. This action sucks the gaseous mixture into the cylinder through the inlet valve. The further movement of the fly-wheel causes the piston to move upward, compressing the gas into small volume. While the gas is thus compressed it is exploded by means of an electric spark. The violent expansion of the burning gas drives the piston downward with great force. The movement opens the exhaust valve, the burnt gases escape through the exhaust pipe and the fresh mixture is drawn in again to be compressed and exploded as before. If the engine has more than one cylinder the same process is repeated in each one. This is the operation which is continued so long as the supply of gasoline holds out.

In the steam engine the vapor acts alternately on each side of the piston head, but in motor boats and automobiles it acts only on one side. The speed with which this is done is amazing and the same may be said of the steam engine.

The swift rise and fall of the piston acting through the connecting rod turns the shaft directly below, which whirls the screw around at the stern. The electric spark that explodes the vapor is generated by a dry battery or by a magneto-electric machine driven by the motor itself. There is also the "make and break" spark, to which we need give no attention. The two ends of the wires in the spark plug which is screwed into the cylinder are separated by a space barely the twentieth part of an inch, across which the spark leaps, giving out an intensely hot flash.

You understand, of course, that I have given simply the principle and method of operation of the engine belonging to a motor boat. There are many parts that must operate smoothly and with the minimum of friction. Lubricating oil is as essential as gasoline; the ignition battery must be kept dry; you must know how to operate the reversing lever, to shut off, to start and to hold the desired speed. Except when racing or under some pressing necessity, the swiftest progress is rarely attained, for it is trying to all parts of the engine and consumes a good deal of fuel, which cannot be bought for a trifling price.

You would be confused by any attempt on my part to give a technical description of all the motor appliances, nor is there need to do so. If you have just bought a motor boat, you will be taught how to control and manage it by a practical instructor, and such instruction is better than pages of directions. To show the truth of what I have just said, I will quote a single paragraph from the description of the boat concerning which I shall have a good deal to say in the course of my story.

"The keel is of white oak, with specially bent elm frames. Planking of selected Laguna mahogany, finished thickness one-half inch, in narrow strakes and uniform seams, secured to frames by copper boat nails, riveted over copper washers, all fastenings being of bronze or copper to withstand salt water. Seams of hull caulked with special cotton payed and puttied. Outside of mahogany planking, finished in natural wood with spar varnish. Watertight bulkheads fore and aft which assist in floating the launch in case of accident. Decks and interior woodwork finished in selected Laguna mahogany. Steam bent quartered oak or mahogany coaming extending around cockpit."

Alvin Landon's launch was thirty-five feet long, with six-cylinder, sixty-horse power motor and a guaranteed speed of twenty-four miles an hour. The motor was placed under the forward deck, where it was fully protected by a hinged metal deck. To become somewhat technical again let me proceed:

All the valves were placed on the same side, the camshaft (operating the valves) as well as the pump shaft being mounted on ball bearings. The crankcase was of tough aluminum alloy, and lubrication was well provided for, being kept at a constant level in the crankcase by a geared oil pump. A gear-driven pump circulated the necessary cooling water for the cylinders, which passed out through the copper exhaust pipe at the stern. Only one operating lever was employed and that was placed directly at the helmsman's left hand. The gasoline tank contained fifty gallons and was under the after deck with a pan below it for safety's sake, draining overboard. The propeller wheel and shaft were of bronze.

Alvin's motor boat, thus partially described, included the necessary deck hardware, "such as brass chocks and cleats, flag pole sockets and flag poles, ventilators to engine compartment, rubber matting for floor, cushions and upholstered backs for seats, three sailing lights, oars, rowlocks and sockets, compressed air whistle with tank, two pairs of cork fenders, bell, foghorn, boat hook and portable bilge pump, six life preservers (as required by the U. S. Government), a twenty-pound folding anchor and a hundred feet of strong manila rope."

We must not forget the glass wind-shield. Passengers and crew were always guarded against flying spray and sweep of wind and rain. Nothing that forethought could provide for the safety and comfort of all was forgotten.

Suppose young Captain Landon stepped on board the Deerfoot with the intention of starting out on a cruise. He would first turn on the switch which controls the electric current for the jump spark, open the valve that allows the gasoline to flow from the tank into the carburettor, swing around the fly-wheel and then assume charge of the lever and steering gear. But lo! the engine refuses to respond. There is no motion. What is the cause?

There may be a dozen of them. In the first place, the battery may be worn out; there may be a lack of compression due to leaky valves; perhaps, after all, he forgot to place the switch key in position; the spark plugs may be fouled or cracked, the gasoline shut off, the gas mixture imperfect, no gasoline in the tank, water in the cylinder caused by a leak from the water jacket, or water in the gasoline.

It may be that when the launch has covered a good many miles the engine suddenly stops. The cause may be faulty ignition, because of a disconnected wire or a loose terminal, exhaustion of the gasoline, or derangement of the magneto, or poor carburettor adjustment.

But I have said enough to give you an idea of what the expert handler of a motor boat must understand. It may seem almost a hopeless task, but, as I stated at the beginning of this chapter, patience and application will enable you to overcome all difficulties and make the handling of the craft an unalloyed pleasure.