A MOTOR BOAT
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.