The wind has four
different effects on a sailboat, which must be understood by
the amateur sailor before he can begin to see why his boat
performs differently under different conditions of wind and
sailing course.
The wind drives the
boat ahead-most important of all; it also drives it laterally
or, to speak in a nautical term, causes it to "make
leeway"; it heels the boat over, and lastly, turns it
around, according to the balance of her sails, distribution of
weight, and what is known as the "center of lateral
resistance." The proper handling of sails and rudder is
what enables the sailor to so utilize these effects of the
wind that he may sail his boat in any direction.
The propelling effect
is the one most utilized, and it is for this reason that every
boat is constructed to offer the least resistance to its
forward movement with as little friction as possible.
Leeway is one effect
to be avoided, and for this purpose boats are given either
deep, stationary keels or centerboards, or some other device
for providing an extensive lateral surface below the water.
Heeling and the
stability of a boat go hand in hand. The boat must be
prevented from capsizing, and this is done either by putting
lead or iron on the keel, or carrying ballast in the hull in
order to lower the center of gravity, or by building a broad
and shallow boat such as the cat boat, which is very stiff in
a breeze and does not heel readily, but when a certain point
has been reached, is apt to capsize quickly in the hands of an
unskillful sailor.
The fourth effect is
that of turning the boat around. This is done when the center
of effort on the sails does not come on a line with the center
of lateral resistance. This is always the case in a poorly
balanced boat. A well-balanced boat requires very little
movement of the rudder to hold to a course.
Any novice can
understand how a sailing boat can travel with the wind, but
why it should go forward when the sails are close hauled is a
question of dynamics which we will not try to explain in this
short article. An easily understood explanation of why boats
go ahead instead of sideways can be made by taking a V-shaped
block of wood and pressing it between the thumb and
forefinger. If sufficient force is used it shoots forward
quickly. The thumb may be likened to the wind and the
forefinger to the water on the opposite side of the boat. The
pressure caused by the wind pushing the boat against the water
on the opposite side causes the boat to go forward.
The center of effort
and center of lateral resistance must be understood in the
handling of a sailboat. The center of effort is the center of
the total sail area. If, for example, this comes forward of
the center of lateral resistance when the boat is sailing with
the wind abeam, then the side pressure on the sails will turn
the boat's bow in the direction toward which the wind is
blowing, or away from the wind, and a boat doing this is said
to carry a "lee helm."
On the other hand, if
the center of lateral resistance is farther forward than the
center of effort, the wind will swing the boat in the
direction in which it is blowing, thus throwing the bow up
into the wind. A boat doing this is said to carry a weather
helm. Every sailing boat should be so rigged as to carry a
little weather helm, as, if struck by a squall under those
conditions, it will luff quickly up into the wind and so be in
safety, while if the lee helm is carried, the boat will fall
off before the wind, presenting a broadside to wind and wave
which is very apt to cause it to capsize.
Too much weather helm
is also to be avoided, as it makes it necessary to keep the
rudder over at a sharp angle and retards the progress of the
boat.
To reduce weather
helm, move the ballast aft or shorten the after canvas, or
increase the forward canvas by setting a larger jib. If a boat
carries a lee helm, shift the ballast forward or reduce the
area of the head canvas.
In considering the
action of the rudder, the amateur sailor should bear in mind
that as the boat is turned by the rudder, it swings as on a
pivot. The water, pressing against one side of the rudder,
pushes the stern of the boat away from that side.
The pivot or turning
point is always well forward of the center. This is a fact
that should be remembered when steering close to a boat or
other object. Don't delay turning out of the way too long, or
the very act of turning your boat will throw the stern over
sufficiently to cause the collision you are trying to avoid.
Running before the
wind may look like the ideal course to the amateur sailor, but
a little experience cures him of that belief. Steering
is difficult when running with the wind aft, especially in
rough water, and there is danger of the sail gybing over when
least expected. Except on smooth water it is better to haul
the boat up so as to have the wind on the quarter, and after
following that course for some distance, to "take the
other track", gybe over so as to bring the wind on the
other quarter. The proper location or direction of the
boom, or, in a nautical term, how the sail should be trimmed
is of supreme importance. The wind on the quarter, the wind
abaft the beam, the wind abeam or directly at right angles
with the boat, and the wind forward of the beam.are what are
known as favorable winds, the sheet being hauled in such
proportion as to give the best results. These positions
all refer to a boat when it is what is termed "sailing
free."
To sail "close
hauled" means to bring the boat up as close into the wind
as possible and still keep it on its course, with the wind
filling the sail so as to drive it forward. A properly built
boat will lie within four or four and a half points of the
wind, while some, especially those built on racing models,
will do even better than this. Figure 6 shows about the proper
location of the boom when sailing close hauled. The wind
striking the sail at this angle will drive the boat forward
and maintain a reasonable degree of speed, while to haul it
closer would increase the leeway until, if the sail were
hauled parallel with the keel, the only progress made would be
to leeward. Most boats will sail closer to the wind in smooth
water than in a rough sea.
When sailing close
hauled, it is necessary to hold the boat on a course that will
just nicely keep the sail filled with wind. This point can be
ascertained by putting the helm slowly to the leeward. As soon
as the sail begins to shake near the head, you have reached a
point where it is not drawing as much as it should, and, if
the helm is kept down, the sail will begin to flap in the wind
and the boat will lose headway. A little practice will enable
an amateur skipper to see the beginning of this
"tremble" in the sail, and at the first symptoms he
must reverse the helm until the wind fills the sails fairly.
