The New York herald., 1879-02-06
CONSTRUCTION OF KEEL YACHTS.

LECTURE By PROFESSOR A. CARY SMITH BEFORE
THE sEAwANHAKA YACHT CLUB.
Professor A. Cary Smith commenced course Of
lectures before the Scawanhaka Yacht Club last
evening at meeting of the club and others interested
in yacht building, held In Delmonicos. Broadway
and Twenty-sixth street. The subject of the first
lecture the construction Of keel yachts and
illustrated by drawings and by diagrams on the
blackboard.
Professor Smith said:-"As the keel is merely
means of getting lateral resistance 1t would that
tho more keel immersed the better; but when we ex-
anime closely into the laws of fluids 1t is found that
such is not the The great problem Is how to
make the least surface do the most work. The
OF this is that surface friction great factor also
when the water has been parted the effective ateral
resistance grows less and less approach the
after end of the boat. Experiments by Bland with
small models show this. and practical experience
points to the same thing II would that the
law governs the contour of the keel that gov
erns the shape of water line--an easy entrance,
with tho greatest width aft OF amidships and full
round curve aft; but want place to hang u rud-
der and we leave the after end perpendicular for
that purpose.
needed to make a vessel hang on In seaway But
experience does not show this. The old America
scarcely any forefoot and she Is perhaps the most
weatherly keel boat we have. The English Jullanar
is another excellent example and shows this to still
greater degree only drawing fourteen inches forward
and thirteen feet nine inches aft with the stern post
about fifteen feet from the after end OF water line
The immersed area compared with the depth. mul
tiplied by length OF water line, IL very small yet her
record shows her 10 be the most weathery boat of
her rig In rough water. and she turns very quickly
too, great advantage in beating to windward when
In short work. Tho same result can be obtained by
reducing the draught forward and rounding up the
keel aft leaving the stern post perpendicular. This
form brings the centre of lateral resistance well aft
and allows us to carry less bowsprit l need not
point to the fact that this s great advantage This
form of keel holds good even in shallow centre
board boats. The Comet and Clio have almost no
forefoot, and both are remarkable for wcathcrly
qualities.
THE CROSS SECTION
CAS- we have now" said the Professor, ssplanccd
over the reasons for the form OF the keel we now
come to the cross section. II Is the practice to make
the keel very thin and deep. This is good form for
speed but very weak In construction except for very
small boats. Where u vessel with q thin and deep
keel touches the ground far from dry dock II Is
very unpleasant and yet most keel boats built In
this manner When keel s thin there Is little hold
for the floor tmbers, and IL the cardboard strake Is
thick as should be there is small space for the
rabbet-a bolts must be driven the centre, and,
If repaired, there Is very little space to put any
edge OF the keel 10 sometimes s. there is danger
OF twisting the keel entirely out II the vessel takes
the ground III we intend to put any lead on the
Keel IL must bo made very thick, IL for small boat,
and only short distance outside the plank II Tor
large one.'
In conclusion, the Professor said that keel boat
should be and of good depth to get the rcqui.
site lateral resistance This form enables us to get
along with small rig and yet sail WELL when neineu
with a strong wind shallow keel boats are apt to fall
to ecward and lose In that way. deep keel may DC
put on, but 1t is very weak " construcuon'