This chapter is mildly theoretical, and may be skipped by the reader
who believes in nothing that is not, in the ordinary sense of the word,
practical; for in it he will find no definite instructions, but only a
description of the behaviour, under different conditions, of the skis
when in motion, and an attempt at an explanation of it.
I advise him, however, to try to read it, for I think that what I have
to say here is, in a broad sense, strictly practical. I am convinced
at any rate, that if, when I began ski-ing, some one had given me the
information which I am about to try to impart, and which, for the most
part, I have slowly collected for myself, I could have reached in a
month the very moderate degree of skill which it has taken me five
seasons or so to arrive at.
If the reader can thoroughly grasp the few facts with which this
chapter is concerned--and he can take my word for the facts, whatever
he may think about my comments on them--he will, I think, find it far
easier to understand, remember, and put into practice the instructions
which he will find in the subsequent chapters, as to the various
swings, turns, and other manoeuvres for controlling and steering the
skis, and keeping the balance while running downhill.
Before proceeding any further, I had better, in order to avoid any
chance of being misunderstood, explain certain terms of which I shall
constantly make use throughout the rest of the book. These terms
are the "edging" and "flattening" of the skis, and the "inside" and
"outside" of a curve.
If any reader feels that an explanation of these terms is an insult to
his intelligence, I can only assure him that such an explanation has
been necessary in the case of many of my pupils.
The terms "edging" and "flattening" simply have reference to the
relation of the plane of the ski's sole with that of the general
surface on which it is resting, and do not refer to its relation with a
horizontal plane, or, in other words, to its position in space.
Thus a ski is "flat" when standing in the normal position on level
ground; but, when standing in the normal position on the side of a
slope, it is _not_ "flat," but "edged," for in this case the edge
nearest the hill cuts deeper into the snow than the other although the
plane of the sole is still horizontal. (Fig. 20, A and B.)
[Illustration: FIG. 20. Edging and flattening.]
The case is altered when the ski is inclined sideways; on level ground
a ski that is inclined sideways is "edged" (C and E); but on the side
of a hill a ski when inclined sideways so that the plane of its sole
becomes parallel with that of the surface of the slope, is _not_
"edged" but "flat" (D). When inclined to the opposite side, however,
it is, of course, "edged" even more strongly than in the normal
position (F).
The inside and outside of a curve mean, respectively, the sides nearest
to, and farthest from, the centre of the circle of which that curve is
an arc; that is to say, that in speaking of a swing or a turn to the
right, the right ski, foot, and so forth are the inside, and the left
the outside ones, while in the case of a turn to the left it is just
the reverse.
This is simple enough. A shade of ambiguity, however, may lie in
the fact that the edges of a ski are generally called "inside" and
"outside" with reference to their relation to the foot, in the same way
as those of a skate. In speaking, then, of swings or turns, the right
edge, say, of the right ski may be referred to as its "outside" edge,
even when the right ski itself, and the right leg, shoulder, and so on
are all the inner ones in relation to the curve of the swing.
Now for the facts referred to above.
When a ski is pointed directly downhill and is made to slide with its
sole held flat on the snow, it runs, if properly constructed, in a
perfectly straight line.
If it is then "edged" to one side it runs round gradually to that side,
the curved point acting against the snow like a bow rudder and drawing
it to that side.
The steering effect, in theory, increases with the edging until it
reaches its maximum when the ski is edged to a right angle. What
happens in practice is that though the edging and the steering effect
do increase together, there is no use in edging the ski beyond a
certain angle--less than 45°--as, if that angle is exceeded, the ski
sinks deeply into the snow and refuses to slide.
If that angle is not exceeded, however, the deeper the ski sinks into
the snow (owing to the softness of the latter) the greater is the
steering effect, for then a larger and more sharply curved surface of
the point comes into action as a rudder.
If when going straight downhill the runner "edges" his ski--we will
suppose he has only one--_by simply leaning sideways_, he will equally
simply fall down; but if he "edges" it _without leaning_--if he edges
it _in relation to himself_, so to speak--it will begin to turn; that
he then leans sideways in order to keep his balance does not make the
turn sharper.
If the runner traverses the slope with his ski held normally, as in
Fig. 20, B, it will run straight, for although it is then edged in
relation to the slope it is not edged in relation to him. If he edges
it in relation to himself it will turn more or less according as the
gradient of its previous traverse has been steep or gradual.
When a ski running straight downhill is made to turn by "edging," the
further it turns, and the less directly therefore it points downhill,
the less abrupt becomes the curve of its course. This curve, indeed,
eventually becomes so gradual that before the ski has turned far enough
to point horizontally across the slope and come to a standstill, the
line of its track is practically straight.
When, therefore, a ski, traversing directly at a moderate gradient,
is simply "edged" towards the slope, there is no perceptible turning
effect, even if the runner does not lean inwards.
At first sight it might appear that the movement of a ski when edged
and travelling in a curve would be precisely similar to that of a
skate, and so it is in a way.
Since the edge of a skate is, in shape, the arc of a circle, a skate,
when edged, cuts cleanly round without side-slip, and so in a sense
does a ski, when simply edged, for its heel then follows in the track
of its point. An edged ski, moreover, like a skate, turns more or less
gradually, according to the angle at which it is edged. But while a
skate, the edge of which is curved throughout, touches the ice with
only a very small part of this edge, and is able to make a curve of
very small radius, a ski touches the snow with nearly the whole length
of its edge, the greater part of which is quite straight. This straight
part so far neutralises the turning action of the curved point, that a
ski made to turn simply by edging is unable to make anything but a very
long and gradual curve--so gradual, indeed, that for practical purposes
of steering the edging of the ski, _unaided_, is absolutely useless.
[Illustration: FIG. 21.]
But though, contrary to what one might expect, the edging or flattening
of the skis may practically be disregarded as _primary_ factors in
a turn, they are, as we shall see, of the greatest importance as
_secondary_ ones.
Before a ski can be made to turn at all sharply, its heel must be got
out of the track of its point and made to travel faster on a curve of
its own (as in Fig. 21, B). The ski as a whole, in fact, must be made
to side-slip more or less as well as move forward.
The first question, then, is how the ski-heel is to be got out of
the track of the point in order that the side-slip may start. If the
ski is pointing nearly directly downhill, whether flat and running
straight, or moving edged in a long curve, there is--apart from the
help of the other ski, which we will leave out of the question for
the present--only one possible way of doing it. The runner, by means
of sudden--though not necessarily more than a very slight--muscular
effort must jerk it more or less broadside on. How he makes this effort
need not be considered here; we will also defer the consideration of
the other ways in which the side-slip may be started. Supposing it has
been started, it must then, by edging or flattening, be encouraged to
continue, if the ski is to go on turning.
It depends on the quality of the snow as to whether a ski side-slips
more freely when flat or when more or less edged. If the surface of
the snow is hard and icy, or if there is a mere shallow layer of loose
snow on a hard crust, a ski will slip sideways either when quite flat
or when slightly or even strongly edged on the side _from_ which it is
moving.
The flat position would in this case be the more favourable if the hard
surface were perfectly smooth; this, however, it seldom is; it usually
has small projections which, when the ski is quite flat, strike its
side and check or stop it, while, if the edge is raised, they strike
its sole obliquely and affect its motion but little.
The flat position, then, is not advisable as an aid to side-slip even
in the case of hard snow; on snow of any other kind it is still less
advisable, for if the ski sinks deeply into loose soft snow, or even
but a little way into dense soft snow or into a thin crust, it can
hardly be induced to side-slip at all when held quite flat, while when
more or less edged, it can usually (if already in motion) be made to do
so without much difficulty.
The reason is not quite obvious, for at first glance it would appear
that the ski would meet more resistance from the snow in the edged
position than in the flat, but this is not the case, for, when the ski
is edged, most of the resistance is exerted _obliquely_ against its
sole, and so tends to make the ski rise to the surface of the snow and
relieves the pressure. When, however, the ski is flat, the resistance
acts _directly_ against the side of it, and there is no lifting
tendency to diminish the rapidity with which this resistance increases
as the snow is compressed.
[Illustration: FIG. 22.]
Moreover, since during a turn the runner must lean inwards to keep
his balance, the ski cannot remain in its normal position in relation
to the leg unless it is more or less edged inwards (Fig. 22, A). That
the leg and ski should remain as nearly as possible in their normal
relative positions is an advantage, for the more nearly they do so the
less is the strain on the ankle. If the weighted ski is held quite flat
during a turn in which it is outermost, that ankle is placed in a very
unstable position (Fig. 22, B), and is liable to give way and so edge
the ski on that side _towards_ which it is moving (Fig. 22, C); it
will then cut more deeply into the snow and be brought instantly to a
standstill.
[Illustration: FIG. 23.]
In all that I have said so far about side-slip, I have assumed that
the ski is moving more or less broadside on, with its heel travelling
outside the track of its tip and its pivoting point well forward, and
this is what either one or both skis actually do during the greater
part of any swing or turn; for, in turning, a ski usually passes
through the positions of either B or C, Fig. 23. A ski may also, as,
for instance, in turning downwards from a slow traverse, move so that
the curve in which its point travels is outside that of the heel (Fig.
23, D) and its pivoting point is near the heel. In each of these cases,
though one end is side-slipping faster than the other, both ends are
slipping to the _same side_, and the ski, as I have said, has therefore
to be edged to the _opposite side_.
If, however, the ski begins to turn as in D, and finishes as in B
or C, it must of course be edged first to one side and then to the
other, as in E, and for a moment be flat. At this moment the pivoting
point of the ski is at its centre, and its heel is side-slipping in
one direction as much as its point is in the other, as in A. If ever,
therefore, a ski, in turning, _continues_ to pivot on its centre (Fig.
23, A) instead of only doing so for a moment, it must obviously be held
quite flat, as otherwise either one end or the other will cut below the
surface of the snow and be checked suddenly.
Now the pivoting point of a ski is never behind its centre except
during a downward turn, and the faster the runner is moving before the
turn, and the sharper the turn is made, the more quickly this point
moves to the front; the only case, I believe, in which it remains
near the centre for an appreciable time, and when, therefore, the ski
has to be held deliberately flat, being that of the outer ski during a
"steered" Christiania swing.
In order to facilitate side-slip, therefore, the outer edge of
the ski must usually be raised as it turns or, even if at first
the inner edge must be raised, a change of edge must usually take
place almost immediately. The flat position, in fact, must never be
sustained--except, as I have said, during a Christiania "steered"
swing, and even then only for a short time--it is simply a necessary
incident in a change of edge.
In each figure in Diagram 23 the dotted line with arrows shows the
_average_ direction of the ski's course at each point, and whether,
therefore, it must be edged or flat.
The foregoing remarks are an explanation of how the edging or
flattening of the ski can be made to help the side-slip; the next thing
is to understand how the side-slip can be made to help the ski to turn
sharply.
If, when either standing still on the side of a slope or running across
it in the normal, edged position, a ski is partially flattened, it will
begin to slip sideways--in the first case moving directly downhill,
and in the second obliquely, _i.e._ forwards as well as sideways.
Now the foot stands on the ski at about halfway between the front bend
and the heel--that is to say, about the middle of that part of the
blade which rests on the snow; and as long as the runner's weight is
placed equally on toe and heel, a ski in side-slipping will continue to
point in a direction parallel to that in which it was pointing when the
side-slip began.
When, however, the runner's weight is placed on the heel, that end of
the ski will side-slip faster than the other, and the farther the ski
slips the more it will point uphill; while when the weight is placed on
the toe the reverse will happen.
Fig. 24 shows what will happen if a ski, when (A, B, C) at rest on,
or (D, E, F) running across a slope, is made to side-slip with the
runner's weight variously distributed. In this and succeeding diagrams
the blackened portions of the skis are those on which the runner's
weight is put.
[Illustration: FIG. 24.]
In A the ski slips broadside on downhill.
In B it gradually revolves as it slips, and would finish by running
downhill backwards if its shape did not prevent it from doing so.
In C its rotation is reversed, and it finally runs straight downhill.
In D it runs slightly sideways, but the direction of its course is a
straight line.
In E it turns uphill and at a certain point stops.
In F it at first turns and finally runs straight downhill.
The side-slip can be stopped more or less quickly at any stage by the
runner strongly edging the ski and at the same time again equalising
the distribution of his weight on it.
Whether the ski then runs on in the direction in which it is pointing,
or comes to a standstill, of course depends on whether it is pointing
downhill or not.
It is obvious, then, that when a ski is in motion _across_ a slope the
runner, by means of the side-slip, can make it turn in either direction
and to any extent up to a certain limit, and can in this way either
come to a standstill, slightly alter his direction, or run straight
downhill. It is equally obvious that no matter what means are employed
for starting a turn (there are more ways of doing so than I have yet
described), the distribution of the runner's weight on the ski or skis
which carry it may make all the difference to the success or failure of
the manoeuvre.
I have already said that when a ski is running straight downhill it
may be made to turn by the runner jerking it somewhat broadside on. He
can of course do the same with the two skis, but a simpler plan is for
him to stand on one, point the other more or less in the direction in
which he wants to go, and hold it so for a moment. It is thus of course
made to "stem"--in other words, to side-slip--and, if the runner then
throws his weight on to its heel, it can, as we have just seen, be
made to turn still further, the previously weighted one being again
brought parallel with it as it does so. A turn can also be started from
a traverse in the same way.
When one ski is held at an angle with the other in order to start
a turn in the above way, the relative position of the two usually
produces some steering effect; the two skis in fact act together
something like a boat and rudder. To say that one ski may be looked
upon as the boat and the other as the rudder is hardly accurate, for
the steering effect is at its greatest when, as the runner's weight is
shifted from the ski that is running straight ahead to the one that is
held sideways, it rests equally on both; at which moment, since their
area is equal, either of the skis may equally well be looked upon as
the rudder or as the boat. If, however, it is remembered that the boat
steers the rudder no less than the rudder steers the boat, and that if
the rudder is fixed in a certain position, it and the boat together
may be considered as one solid object whose shape determines whether
and how it is able to turn, one may, by comparing the skis with a boat
and rudder, understand whether and how, when held in various relative
positions, _they_ are able to turn.
The diagram shows the skis as they are held at the beginning of--A, a
Telemark, B, a Stemming turn, and C, a Christiania. It also shows a
boat turning to the left steered by both a bow and a stern rudder.
[Illustration: FIG. 25. The darkened ski of each pair is the weighted
one.]
The steering action of the skis may be best understood by considering
the blackened parts of each pair (in which the steering effect is
neutral) as the sides of a boat, and the light point and heel of each
pair as a bow and stern rudder respectively. It will then be seen that
the boat is in each case helped to turn to the left by the action of
both rudders, or that if it can in some way be made to turn to the
left without the help of the rudders, they will at least not hinder
it--than which, as a matter of fact, little more can be said in the
case of the Telemark; though in the Stemming turn there is a strong
steering action while the skis remain in this position, and a distinct,
if weak, one in the Christiania.
The principal factors, then, in the control and steering of the skis
are the edging or flattening of them, the distribution of the weight on
them, and the placing of them in certain positions in relation to each
other. How these various factors interact during the different swings,
turns, &c., will be explained more fully in subsequent chapters, but
before closing this one I want to give some explanation of how a turn
on skis depends as to its character on whether the ski at the moment of
beginning the turn is running straight down the hill or across it, on
whether the speed is high or low, and the slope steep or gentle, and
also on the quality of the snow.
The accompanying diagram shows the successive positions assumed by a
ski (the leading one, the other is not shown) during a turn to the
right, under various conditions.
The line passing through the middle of the skis shows the curve on
which the runner himself travels during the turn; the line ending in a
double arrow shows the sort of curve on which he would travel if the
ski were able to cut round without side-slip as a skate does. It will
be seen that if there were no side-slip he would in every case move
steadily to the right of the line of his original course (shown by a
dotted line in the diagram), but that, on account of the side-slip, the
line on which he travels sometimes moves only slightly to the right of
that line, even when the turn itself is a sharp one, that sometimes it
moves to the left of it and then recrosses it, and that sometimes it
remains entirely on the left of it throughout the turn. To understand
how, according to the conditions, the curve of the runners actual
course varies, is a great help to the balance, for at first one's
instinct is to balance the body as if the ski were cutting round like
a skate, _i.e._ to lean inwards too much, which, of course, inevitably
results in a fall.
In every case the turn is supposed to be made as sharply as the
conditions allow. It will be seen that on hard snow the runner, when
travelling fast, will skid almost directly sideways for some distance
from the spot where he actually finishes turning.
[Illustration: FIG. 26.]
A, B, C, D are turns made while the runner is travelling straight
downhill, or, which amounts to the same thing, while he is running on
the level at the end of a downhill slide. E, F, G, H are turns made
while the runner is descending a slope _obliquely_. A to F are what are
known as uphill turns, which bring the runner to a standstill; G and H
are downhill ones, which enable him to join one tack to another when
descending a hill in zigzags.
If anyone who has done no ski-ing at all reads this chapter, he will,
no doubt, think it very complicated; but if, while actually learning to
ski, and especially while learning the turns, he looks through it from
time to time, I think he will soon understand whatever is not quite
clear, and will, I hope, find that it helps him to correct his mistakes
and to understand and remember his instructions.