ad water-line
of the yacht. It is measured on the deck, because the rounding of the
hull, of course, makes it impossible to get a straight line from bow to
stern on the water.

To get the correct sail area requires more labor. It is determined by
the dimensions of the spars and those of the jib-topsail stay. If it
were not for the length of the gaff a triangle would be formed by the
base-line, the stay and the leach of the topsail and mainsail. Then the
area could be easily calculated. But the projection of the gaff spoils
the triangle, and so the first thing to do is to measure the distance
from the end of the boom to the forward side of the mast. From that
point measure to a point on the bowsprit half-way between the jib-stay
and the jib-topsail stay. These, added together, give the actual
base-line. Then take the height of the mast and the height of the
topmast. The length of the gaff is next ascertained, and from this is
subtracted eight-tenths of the height of the topmast. The difference
between these is added to the actual base-line, the result giving the
corrected base-line.

Experience shows that this addition offsets very accurately the number
of square feet of sail lying between a straight line drawn from the end
of the boom to the sheave of the topsail halyards, and--considering that
line as a base--the two legs of the triangle extending from the end of
the boom to the peak of the gaff, and from the peak of the gaff to the
topmast. Then the length of the corrected base-line is multiplied by the
height of the mast, taken from the deck to the sheave on the topmast,
and the result is divided by two. After obtaining these measurements,
proceed as stated above--that is, add the square root of the sail area
to the length of the load water-line, and divide by two. Then you have
the yacht's racing length. There is no doubt that it is a complicated
problem.

But this method is for sloop measurement. To get the area of a cat-boat
sail there is a simpler way, although it is not so absolutely exact.
Draw a line from the throat to the leach parallel to the foot of the
sail, and let fall from the point of intersection of this line with the
leach another line parallel to the luff. The sail is then divided into a
rectangle formed by these two lines, the luff, and part of the foot, and
two triangles, one of which is bounded by the head of the sail, a part
of the leach, and your first line; the second, by a part of the leac