CHAPTER
1
GENERAL
DISCUSSION
There is a wonderful fascination
about yacht designing because of the opportunity generally afforded the designer
for experiment toward improvement of type, and for the expression of his genius
practically unhampered by the many considerations that closely restrict the
efforts of the designer of commercial vessels.
Another element of fascination is the complexity of the problem of providing the perfect yacht for a given set of conditions. The antagonistic natures of speed, seaworthiness, large cabin accommodations and beauty, with the varying and uncertain effects of waves, change of heel and trim, cut of sails, etc., takes the problem, especially in the case of the sailing yacht, out of the category of strictly engineering problems such as those of the airplane, locomotive or steamship, in which results can be predicted with great exactness by mathematics based on laboratory work.
REQUISITES
OF SUCCESSFUL DESIGNER
It
must not be inferred that science is not an important aid in designing any kind
of a yacht, for it is first in the requisites for consistent success, but with
it must be blended natural genius, imagination and much practical experience in
handling and building boats. It is the combination of these qualifications that
enables a designer to do good work. It is not enough to be fond of boats and
full of inspiration such is distinctly the amateur; it is not enough to have had
years of experience at sea and in the boat shop some ridiculous models are
produced by old sailors who keenly appreciate a good boat but cannot produce
one; it is not enough to know all about resistance, displacement, stability,
etc. — for the purely scientific designer may blunder on many practical
considerations.
The
practical designer will often drift into some particular branch of yacht
architecture as a specialty, such as small racers, large power cruisers, heavy
cruising type schooners, high speed motor boats, etc., for with experience in
one particular line comes proficiency, reputation and increased business in that
specialty. Every boat is an experiment, but in producing a special type the
designer has a great advantage in stepping with confidence, born of experience,
from one design to another with intelligent improvement in each succeeding boat.
This brings out the importance of studying thoroughly the performance of each boat and noting carefully any deficiencies for correction in the next boat. The designer who is engrossed only by the problem of the design and
“GERTRUDE THEBAUD”
production of a
yacht, and when it is done regards it as a closed book and turns all his
attention to producing other inspirational designs, can never be classed as a
consistently practical yacht architect.
ORIGINALITY
IMPERATIVE
Originality,
based on one’s own study and experimental work, is really the keynote of
success. He who does things in a certain way because others are doing it and
always have done it that way contributes little to the advancement of the art.
One should study constantly the work of others, but rather with an eye to
discovering what not to do than what to copy.
Yacht
designing, with its comparative freedom from hampering restrictions, should lead
the world of marine construction in development of form for speed, seaworthiness
and gracefulness. This is the case with sailing craft — witness the great
improvement in fishing vessels that now closely approach yacht form.
Improvements
developed in yacht work should exert greater influence on commercial sailing
vessels than has hitherto been the case. It is generally believed that sailing
ships are practically a thing of the past and are doomed to extinction. I do not
agree to this. The wind is an unfailing source of power, while the supply and
cost of fuel for mechanically propelled vessels in the years to come are matters
of great uncertainty. Even today I believe that for long voyages and bulky
cargoes, an improved type of sailing vessel or auxiliary could compete
profitably with motor ships.
Among
the improvements which progressive naval architects may apply to sailing vessels
are: Better speed to windward by means of radical improvements in form and rig
and the use of centerboards or bilgeboards; economy in man power by free use of
electric auxiliaries, and increased safety by utilization of automatic steering,
stabilizers and modern navigational aids such as are installed on many modern
steam and motor ships. Where a portion of a voyage is necessarily through a
region where head winds prevail, such as rounding Cape Horn from east to west,
the matter of weatherliness is of utmost consequence.
The
ocean sailing vessel of the future may possibly be of the modified fisherman
form and rig, fitted with a Diesel driven electric generator plant which will
supply current for the screw, windlass, pumps, winches, etc. All sheets and
halyards may be of wire, each hauled by electric motor driving a drum on which
all the slack is reeled. She may be equipped with gyroscopic automatic steering
mechanism controlling a power rudder gear. Controls for all motors may be
located at the central station where the officer of the deck can hoist, reef or
trim sail and control the course, hoist anchor or centerboard, and start or stop
the auxiliary screw, all from the central instrument board. In such a vessel a
small crew would be required and the superior weatherliness, steadiness in
steering and accuracy of navigating instruments will greatly increase the
average speed and the safety, bringing the ship into competition with the power
driven freighter.
Figure
1 is a suggestion for such a vessel. A study of long voyages of sailing ships
shows that the low average speed is due to calms or head winds over a
comparatively small portion of the voyage. In the case of one voyage of a
certain clipper ship, it was found that the fuel required to boost speed to nine
knots on the light weather days was only one-eighth that which would have been
required by a motor ship to make the same average speed, under power alone. The
fuel saving figures more than twice the overhead on the rig.
The added safety and ability to make a schedule put the auxiliary ship on
a par with the motor ship.
In
large power yachts designs have, curiously enough, always copied the commercial
steamers of a decade or so previous. Until the advent of the Diesel yacht the
large power yacht always had the clipper bow and short bowsprit, which prevailed
on the best steamers of the middle of the 19th century (Fig. 2). Most Diesel and
steam yachts were then built with the plumb stem and elliptical stern
combination affected by commercial steamships following the clipper bow era.
Progressive
NAVAL
DESIGNER
The
battleship bow shown in Fig. 4 impresses one at first as a ruthless monstrosity,
but on careful study it is found to be a wonderful improvement from the
standpoint of efficiency over bows previously used both in above and below water
form, the bulbous forefoot being a most remarkable innovation, one which could
not have been developed without exhaustive model testing. This bow, in its above
water form, could well be adapted to yacht work, for it is justified by improved
speed and seaworthiness. Such a bow is employed in modified form in the sketch
for a 115-foot water line power yacht (Fig. 5).
It
is interesting to note a tendency on the part of the best designers to return to
the clipper bow type on large power yachts. This form has intrinsic beauty and
seems especially suited to the luxurious pleasure vessel.
DESIGNS
ARE A COMPROMISE
There
are four general characteristics sought after in yacht design:
seaworthiness, large cabin accommodations, beauty and high speed. These
properties do not readily combine; in fact, seldom do we see a successful
combination of more than two of them. The best the designer can expect to do is
to embody in his design the qualities especially desired, treating the other
features in such a manner as to render their deficiencies as inconspicuous as
possible.
The
design of a yacht is too often regarded solely as an engineering problem. There
are certain conditions to be met, such and such a speed must be made, certain
stresses withstood, certain accommodations provided. The skilled designer
produces a craft to fulfill these conditions following methods that are well
understood. After working into his design the above useful qualities he
considers the matter of beauty of design, the purely architectural side of the
problem, the elusive factor that crowns or damns the whole creation.
THE
AESTHETIC ASPECT OF DESIGNING
What
constitutes beauty in marine design? What rules must we study and follow?
Unfortunately, this side of naval architecture has received scant consideration
in standard works on the subject. Every designer is practically a law unto
himself in such matters, and his knowledge of what makes for beauty is largely
intuitive. There is no such wealth of tradition, no such definitely developed
standards of style as exist in the architecture of buildings; nor is this
strange, for a vessel must fulfill many most practical considerations and the
purely aesthetic features must come last. There are various architectural
features, standards of days gone by, such as quarter galleries, high
poops, poop,
lanterns, gun ports,
figureheads and the clipper bow that may be classed as belonging to the
aesthetic phase of naval architecture but which, for practical reasons, is now
all but obsolete.
Some
of these features can occasionally be used for special requirements, such as a
power houseboat in which a picturesque and distinctive appearance is sought.
UTILITY,
SYMMETRY AND HARMONY
Although there are no definitely formulated rules for the attainment of beauty in design, I believe the fundamental principles governing the subject may be laid down somewhat as follows:
To
begin with, the keynote of the matter is utility.
Every feature of the design should be an expression of some useful purpose;
otherwise, it is not justified. Any innovation which constitutes a distinct
improvement, however strange and repellent it may seem at first, soon becomes
acceptable from the standpoint of appearance. But if it is false, added merely
for looks, away with it! It cannot continue to be considered good taste for it
does not fulfill the condition of utility.
The
design in its entirety should be a frank, vigorous declaration of the use to
which the boat is to be put. If she is a cruiser, every line should tend to give
the impression of strength, seaworthiness and comfort; if a racer, the
refinement of design and construction should indicate speed; if a working boat,
her sturdy lineaments should proclaim her commercial employment.
Another
important principle is symmetry. It
has extensive application in every phase of the design. Symmetry of distribution
of displacement, of distribution of weights, of the form of underbody and of
top- sides, are important and any design that violates this principle must fail
of success. Every vessel is necessarily symmetrical transversely — that is,
both sides are exactly alike — but longitudinal symmetry is not so necessary.
Still, the fore body in its general bulk or mass should not be far different
from the after body below and above the water. The freeboard forward will
naturally be greater than at the stern, but enormously high bows and low sterns
are distinctly bad for a variety of reasons. If the character of the design is
such as to call for a wide, flat stern, the freeboard should not be as great as
with a fine, sharp stern. It has the same bulk or volume on a smaller freeboard.
Deckhouses and erections may be treated to carry out this idea of symmetry. An
instance in point is the location of the funnel in steam yachts. This should be
at, or close to mid-length to produce the best effect.
Still
another principle the importance of which I wish to emphasize is harmony.
A vessel is a complex creation having many features that, however perfect in
them, must blend into a harmonious whole. Certain types of hull call for certain
rigs or certain styles of deckhouses; certain types of bow belong with certain
types of stern, for while each may be beautiful, considered separately, they may
be utterly incongruous both for aesthetic and practical reasons when used
together. The chief components of the visible entity of the boat are the bow,
stern, contour of sheer, general freeboard, mass of deck erections, size and
rake of spars, funnel, etc. It is impossible to lay down any test for harmony.
Familiarity with this principle must come through practice and observation. A
full appreciation of this subtle principle of harmony is evidenced only in the
work of the most proficient designers. A man who has mastered it might be termed
a naval artist.
PROGRESS
IN SAILING YACHT DESIGN
Marked
development in the form and rig of sailing yachts has taken place in the last
thirty years. Overhanging bows, fin keels, longitudinal framing, hollow spars,
crosscut sails and wire halyards are some of the great improvements and,
remarkable to relate, practically all are the work of the great designer, Nathaniel
Greene Herreshoff.
The
most marked development of form in sailing yachts that has occurred is in the
shape of the bow. This is the natural outcome of racing rules that used water
line length as a basis of comparison. It was found that sail-carrying power
could be increased independently of water line length by increase of over all
length, especially in the bow. This increasing of the stability is the principal
function of overhangs, and results from an easing of sailing lines and a general
shifting to leeward of the center of buoyancy when heeled. There is scarcely any
limit to the increase in stability that may be secured by lengthening and
flattening the overhangs. The tendency to overstep in this direction in racing
yachts has, fortunately, been checked by rating rules, and in cruising yachts by
the dictates of common sense.
The
problem of designing a sailing yacht with speed as a foremost consideration is a
most complex one. External conditions to which a yacht is subjected, such as
force and direction of wind, condition of sea, etc., are constantly changing so
that the attainment of a given speed may not be sought, but rather such a form
as shall be easily driven at all speeds within appropriate limits. Nor is this
the only consideration, for ease of form must be sacrificed to some extent for
sail-carrying power. A harmonious adjustment between power and resistance should
be sought. The problem of power yacht design is much more simple, as there the
hull may be so designed as to be most easily driven at the desired speed, for,
contrary to early theories, the hull most easily
driven
at one speed is not most easily driven at all speeds. Then, again, the
power-driven yacht travels on an even keel, ordinarily, and the form of the
yacht need be but little affected by considerations of stability.
STILL
ROOM FOR
In
spite of the great advance made in yacht design in the past few decades, one
need not fear that the possibilities are by any means exhausted. It should be
the ambition of every designer to contribute his part to progress in the art.
Eliminating from consideration the matter of improvement in marine motors, a
field in which vast strides will probably be made within a few years, there are
many directions in which advancement may be made — improved sails, possibly
double surface sails with efficiently curved surfaces like airplane wings,
improved spar stepping to eliminate depressing component of wind pressure,
adjustable sparring for correction of balance, improved boat stowage, some
simple anti-rolling device for power yachts, some method of temporarily
increasing lifting surface area of hydroplanes when starting to plane, reduction
of resistance of shaft supports, improved planing forms, etc.
The
progressive designer will do a lot of experimental work on his own account for
the accumulation of data along lines where it is scarce, such as for the
determination of stresses in spars and rigging with various rigs, resistance of
special forms, strengths of special light planking systems, wind pressures on
sails, value of new rust-proofing processes and alloys, efficiency of bottom
paints, holding power of various types of anchors, strength of turnbuckles,
etc., etc.
Most
of the investigations indicated may be made without expensive apparatus.
Resistance, stresses, pressures and strength may be determined with sufficient
accuracy to be instructive through the use of models in ways that I shall
outline later. First hand information is the most valuable kind, and independent
investigation in some of these fields will be of great value to the designer,
directly and indirectly.