1S8 
FOT^EST AND STREAM. 
U.; Almeric H. Paget, Milu P. Palmer, William S. 
Spaulding, John T. Spaulding, Charles H. White, David 
B. Gilbert, Thomas B. Fisher, Frank L. St. John. John 
R. Achims. Whitney Warren, Charles D. Wetmore, Capt. 
William M. Folger, U. S. N.; Clavton Mavo. Clarence 
S. Day. Lieut. William P. White. U. S. N.; Walter Wat- 
son, Jr.,; J. Berr}^ Underhill. Paymaster Reah Frazer, 
V. S. N. ; Oliver W. Buckingham, Lewis Nixon, Fred- 
erick H. Lee, Juan M. Ceballos, Randolph Hurry, Will- 
iam F. Stafford, Gustav E. Kissel, B. F. O'Connor, 
Charles Prver, T. O'Connor Sloane, Paymaster William 
W. Gah, U. S. N.; George C. Pease, and J. E. Martin, 
Jr.; Commander Charles C Cornwell, U. S. N. 
Gasolene Engine and Launches. 
V>\ F. K. GRAIN. 
Ix the following articles it is not proposed to attempt 
to enter into minute details of the theory of motors, boats 
and other parts, but rather to give the average owner 
or would-be purchaser a clear, general idea of the sub- 
ject, together with instruction.s and wrinkles derived 
from personal experience covering a period of some fif- 
teen j'-ears. 
All technical terms have been dropped as far as pos- 
sible. Although there are, as will be noted later on. 
Other motors of note, thej' are each in a class by them- 
selves, and these papers are therefore confined to the 
internal combustion or gasolene motor, it being the most 
common type, and without question the one that in the 
-near future is destined to supplant all engines for launches 
having the power exerted on a piston. 
Motors. — -The internal combustion motor, or what is 
better known as the gasolene engine, is fast becoming 
very popular with launch owners. The up-to-date motors 
cannot be set on fire or exploded by the most ignorant 
handling, and are all very economical in consumption of 
fuel. 
TyPE.s. — These motors arc divided into two classes, 
viz., those having an impulse of the piston by the ex- 
panding gas every second revolution, and known as the 
Otto or four cycle, and those having an impulse every 
revolution, known as the Day or tivo cycle motor. 
Each of these types has. among makers and users, its 
claimants for superiorit}*, but personally the writer after 
equal experience in the use of both cannot see that in 
either economy or ease of handlijig, durability or sim- 
plicity, there is any choice. 
Four Cycle. — We will first take up the four cycle 
system, In these motors the first downward stroke of the 
piston acting as an air pumn draws into the cylinder 
a charge of gas, then on the return or up stroke it is 
compressed in the top of cylinder, or what is known as 
the clearance .space, to about three to five atmospheres, 
or 45 to 75lbs. pressure, and just before reaching the 
upper end of stroke ignited by means of either a red- 
hot tube or an electric spark, when the gas expands and 
drives the piston down. Just before reaching the end of 
the downward stroke the exhaust port is opened, allow- 
ing the burnt gases to escape. The exhaust port then 
remains open during the next up stroke in order that 
the pressure of the rising piston will entirely clear the 
cylinder of all remaining gases, the exhaust port now 
closes and the piston descends, drawing in a new charge 
of gas. 
With these motors the firing device, pumps, valves, etc., 
are all worked from a time shaft by means of gear wheels 
on the main shaft, thus imparting a full working stroke to 
these parts only on every other revolution of the motor. 
In order to impart a steady motion to the motor during 
the idle stroke, the fly-wdieel requires to be of great 
weight and diameter. 
Two Cycle. — The two cycle or Day hiotor obtains an 
impulse of the piston each revolution. All motors of this 
type now in successful use have what is known as a com- 
pression crank pit, that is to say, the part of the motor 
forming the lower frame crank chamber and main bearing 
is an air-tight chamber, opening into the cylinder on top; 
therefore when the piston is on its up stroke a charge 
of gas is drawn into this chamber through a self- 
acting valve; then, on the piston descending, the gas is 
slightly compressed, being thereby forced through a port 
opened by the ascending piston and ignited at the proper 
time. The exhaust gases are expelled through an ex- 
haust port opened by the piston near the end of its 
stroke. In order to cleanse the cylinder of all burnt 
gas, the inlet is generally timed to open a little before 
the closing of the exhaust port in order that the fresh 
gas will expel the burnt gas. 
These motors are claimed to be wasteful on account of 
a part of the unused gas escaping with the exhausted 
gas, this w^e will discuss later on. 
This motor requires less fly-wheel, owing to its getting 
an impulse of the piston each revolution, and run with 
less vibration than the four cycle motor. 
Ignition. — There are three methods of igniting the 
gas in the cylinder, by a hot tube, electric spark, and what 
are known as self-igniters. 
Hot Tubes.— The hot tube ignition is by means of a 
hollow tube with a closed end, projecting int6 the top 
of cylinder. A small flame from a gasolene torch, kept 
constantly burning, is projected into this tube, heating it 
sufficiently to ignite the charge when compressed. This 
method of ignition has been almost entirely superseded 
in marine motors by the electric igniters. The difficul- 
ties with the hot tube are liability of the lamp blowing 
out, the time required to heat up the tube at the start 
(five to ten minutes), and as the tubes burn out they 
have to be renewed; last, but not least, it is very diffi- 
cult to time the exact moment of ignition, as any 
variation in length, thickness or in the composition of 
the metal from which the tubes are made will cause any 
particular tube taken from the same lot to fire either in 
advance or later than the one previously in use. It 
also requires considerable gasolene to heat the tube. The 
advantages of the hot tube are that it is not so com- 
plicated as the electric battery, and if the tube is not 
burnt out and the torch kept going is sure to work. 
Electric Spark. — The electric igniter is in use by nine- 
tenths of the present gasolene motors, and is fast being 
brought to a state of perfection that a few years ago was 
thought to be impossible. Although there are no two 
motor huildcrs using the same designed device as a 
sparker. they are all made on two principles. The first 
is what is known as a wipe spark; this is an electrode pro- 
jecting into the cylinder; the u.sual way is to make a flex- 
ible end something Hke a flat spring attached to or a 
part of a rocker shaft, with an arm, dog or toothed 
wheel running through a .stuffing box gland or remoA'able 
bearing into the cylinder, so that when motion is im- 
parted to this shaft it will cause the two parts to come 
together and then separate with a wiping motion, the 
spark being made at the time of separation. These parts 
are usually made ,so that the working part is free to 
charge from the entire iron work. The other, which is 
usually called the electrode, has a direct connected wire 
and is insulated by means of mica rings or washers, so 
that it gets no current from the motor. This method has 
the advantage of making a very large and strong spark, 
but owing to the constant wear of the sparking surface 
requires a great deal of attention to keep it in time. It 
is not adapted to motors of very high speed, as in- 
crease of speed diminishes the volume of spark, conse- 
quently those using this system of sparking, although 
being good, easy and sure starters, are apt to fail or skip 
impulses when speeded up. 
The next mode of sparking is made by having an elec- 
trode as on the preceding device, but in place of the 
wiping motion there is a small arm or rocker shaft 
which" touches the electrode and is then separated by 
the quick action of a spring; it is like the action of a ham- 
mer dropped lightly on the head of a nail, and then 
lifted of? quickly; for this reason it is generally called the 
hammer sparker. The disadvantage of this is that the 
spark is snufill, and although very economical, it requires 
more battery power than the wipe spark in order to al- 
w'ays keep it up to its full capacity. It has the advantages, 
however, of requiring very little, if any, adjustment, and 
makes the same volume of spark at all speeds. 
diluted more or less by admitting more air through an 
adjustable air cock, either directly into the engine or 
between it and the carburetor. 
This generator is cumbersome, requires cleaning, owing 
to deposits of thick oils, and in most cases will only- use 
successfuly special grades of gasolene. Unless there is 
an intermediate valve between the carburetor and the 
motor it is liable to explode or get on fire through a 
fire back from the motor, which is caused by something 
getting under the seat of the inlet valve, or through de- 
fects in design and construction. 
Pump Generator. — There is still another generating 
system used on a few motors, though it has been dis- 
carded to a great extent; but which, if it were possible to 
overcome its defects, would make an ideal method of 
feeding gasoline. It consists of a small plunger pump, 
worked from a rocker shaft or by other means, which 
throws or injects a small spray or drop of gasolene direct- 
ly into the inlet port of the motor. The quantity of gaso- 
lene is regulated in most cases by a very clever 'means, 
which varies the stroke of the pump plunger at the will 
of the operator, thereby governing the amount of gaso- 
lene as required. This plan has the advantages of sim- 
plicity, safety and also that the gasolene tanks can be 
placed in any position, not having to depend on gravita- 
tion to secure the flow of oil. As for vaporizers or car- 
buretors, which require a gravity feed, unfortunately all 
pumps, owing to various causes, especially in the small 
sizes, will at times over or under pump, in other words 
they fail to supply a uniform amount , which is fatal to 
the successful working of the motor. 
[to be continued.] 
KODV PLAN OF KNOCKABOUT. 
Self-Igniters. — The self -igniters are a means of ignit- 
ing the gas by the heat generated in the motor. They 
consist mainly of a certain metal projection in the cylin- 
der, made from some composition that is heated by the 
burning gases, and which retains sufficient heat to ignite 
the charges from stroke to stroke. 
None of these igniters will work until after the motor 
has been at work a sufficient time to get thoroughly 
heated, therefore it is necessary to have other means to 
start the motor. There are a number on the market, but 
we have not as yet seen any that we could recommend as 
being either reliable or advantageous. 
Gas Generators. — The ways of generating gas from 
gasolene for use in motors are numerous, but the two 
mostly in use are : First, the vaporizers, which, although 
made in manj^ different lorms, are to all practical pur- 
poses the same. 
Vaporizers. — The general principle is a small vessel, 
some only the size of an egg, having a self-acting valve 
which, on the engine making suction, opens, allowing 
a charge of air to enter, and at the same time a small 
quantity of gasolene through another opening. The air 
vaporizes the gasolene and it is then drawn into the cyl- 
inder or compression chamber of the motor, as the case 
may be. On some there is a fixed amount of gasolene 
used, and in order to make the right mixture the air in- 
let is gauged by means of an air valve; in others the air 
supply is fixed, and the gasolene gauged. We think the 
latter by far the best and most economical. The above 
generators or vaporizers are fast superseding all others, 
as they are compact, free from danger, will use almost 
any grade of gasolene, and 9.re not so sensitive to atmos- 
pheric changes. 
Carburetors. — Carburetors were among the first gas 
making devices u.sed on gasolene motors, and are still in 
use by a number of builders. They consist of a tank of 
varying size, having in some cases a dome on top, from 
which the gas is drawn to the motor. The generation of 
the gas is produced by having a pipe through which 
the air is drawn, projecting below the surface of the level 
of the gasolene ; thus when the air is drawn from the 
dome above the gasolene a partial vacuum is formed, 
causing the air to come in through the air pipe, and 
rising up through the gasolene, thereby charging the air 
with the vapor. As the vapor thus produced is not 
exactly of the right quality, it in most cases has to be 
A Fast Croisingf Knockabottt. 
The yacht here illustrated through the courtesy of the 
designer, Mr. W. B. Stearns, of the Marblehead Yacht 
Yard, is built to the dimensions and scantling of the 
Boston Knockabout Association, and is fully fitted for 
cruising; at the same time she will be raced in the handi- 
cap knockabout class at Marblehead. This class has 
been very successful during the past two seasons under 
the patronage of the Corinthian and the Burgess yacht 
clubs, and although the yachts which race in it repre- 
sent a decidedly less extreme development of racing fea- 
tures than the raceabout, and are much nearer to the 
original idea on which the knockabout class was founded, 
they are at the same time very smart little craft for their 
length. Not only do they furnish good racing under 
the limitations of the class, but they are quite fast. The 
yacht is building for Messrs. E. I. and W. L. Cropley, of 
Marblehead. Her dimensions and elements are: 
Length- — 
Over all 33l-t. 
L.W.L 2ift. 
Beam — 
Extreme 7ft. Sin. 
L.W.L. 7ft. 2in. 
Draft 5ft. 
Freeboard, least ift. pin. 
Girth, midship section r4ft. 
Displacement . . r 6,700lbs. 
Ballast, lead keel 3,6oolbs. 
Midship section, area 9.5 sq. ft. 
Lateral plane, area 52,9 sq. ft. 
L.W.L. plane, area iir sq. ft. 
Block coefficient 0.14 sq.ft. 
Prismatic coefficient 0.50 sq.ft. 
Sail area — 
Knockabout rig 500 sq. ft. 
Raceabout rig 600 sq. ft. 
The sail and interior plans will appear next week. 
The Question of Overhangs. 
The following interesting letter from Mr. Linton Hope 
appeared in a recent issue of The Field. Mr. Hope has 
summed up the matter very fairly, and we quite agree 
with him as to the great value of overhangs in any ves- 
sel except where they are severel}- taxed, as by over-all 
measurement: 
I trust you will pardon me for reopening the discussion 
on the value of overhangs for seaworthiness; but the fol- 
lowing facts may help to convert some of the adherents 
of the old type to the use of moderate overhangs: 
I think it may be taken for granted that sea-gomg 
smacks are built under the three following conditions: 
(1) The most seaworthy vessel that can be built 
the price. 
(2) The easiest vessel to work with a small crew 'ii 
bad weather. 
(3) The fastest type that will combine the first two 
conditions. 
These three requirenients, I .take it, are exactly tliOiie 
of a cruising yacht, so the type suitable for one should 
suit the other to a great extent. 
Every one will probably admit that the fisherman is the 
most conservative of all that conservative race, the Brir- 
ish sailor, and that there must be a very strong reason 
for him to change the type of craft in which he has been 
brought up; so, when smacks are being built with con- 
siderable overhang in various parts of the country, there 
must be some very strong reason for such an innovation. 
The first smack I saw with a modern spoon bow and 
long counter was cruising about the Solent a couple of 
years ago, having been let as a yacht for the summc, 
and at the time I thought she was merely a yacht which 
was used occasionally for fishing, as many are. 
Since then I have seen several large North Sea smacks 
in Ramsgate of the same type, and a second and larger 
one in the Solent last year, from Brixham, I believe. All 
these vessels were highly spoken of by their crews as 
able sea boats, and much handier and faster than the old 
type, with straight stems and short, steep counters. 
Within the last few wrecks I received an order from a 
well-known smack-owner and builder in South Wales for 
a ketch smack of twenty tons register for long line fish- 
ing. He ordered a boat with a spoon bow and plenty of 
overhang, as a Brixham smack of this type had lately 
come to that part of the coast, and was a far better boat 
than the local straight-stemmed smacks, and always first 
in with her catch, spoiling the market for the slower 
