YACHT DESIGN
By Ed Fry
FRY Associates, Inc. (FRYCO)
Why a custom design?
Every major yachting center has dealerships and marinas full
of new boats and brokers that list thousands of existing
yachts. So why have a custom yacht designed? There doesn't seem
to be any singular answer to that question. In the case of
yachts up to 100 ft. (30m) there are many very good production
yachts on the market, still some people find, for various
reasons, that available yachts don't quite suit their
requirements. Perhaps they are not fast enough, perhaps the
client is not satisfied with the styling or the arrangement or
the builder’s quality, the list goes on.
For larger yachts there simply isn't a production
equivalent. Most people who have a custom yacht designed have
owned several yachts, know exactly what they want, and for some
reason have not been able to find the "right yacht" in the
marketplace. To most owners a yacht is a very personal thing
and they want one that is arranged and laid out according to
their lifestyle and that is equipped to do the kind of yachting
that they like to do whether it is sportfishing, long range
cruising, fast boating, sailing or just houseboating the
ditch.
Today we find a new generation of boaters that want speed.
Sportfishing yachts are faster because they are fishing further
away from home and they want to get out and back to win that
trophy or prize money. Likewise yachtsmen are not satisfied to
putt long at 20 knots, so fast boats are the order of the
day.
Other clients don't know what they want so they hire an
experienced custom yacht designer to help guide them. These are
the clients that challenge the naval architect to do something
different, unusual or better.
Just how do you go about designing a
yacht?
No matter how much experience you have or how many times you
have gone through the cycle, it always starts with spending
time with the client to find out exactly what is wanted and
then developing what can best be called "the owner's
requirements". This information tells the designer
approximately what size yacht is desired. Whether it is for
high-speed or long-range, whether the owner cruises alone, or
normally has guests, whether the yacht is to be used in
protected waters or full ocean cruising. We learn about the
owner's equipment preferences, principal activities, such as
fishing, racing, cruising, or other water sports. With this
information the naval architect can develop a set of principal
characteristics and begin to come up with an envelope to fit
these owner requirements. Next the designer needs to know the
owner's styling preference, avant-garde, traditional, or just
modern. Usually four or five profile and arrangement plans are
developed and discussed in detail with the client to firm up
his ideas and to give him options to trade off living space
versus sleeping quarters, speed versus range, etc.
After the owner requirements are defined, the serious work
of design begins. The hull form is developed and studied,
multiple powering options are considered, equipment lists are
developed and electrical load analyses are made. At this time
the basic hull structure can be designed and developed. Next
comes the writing of a complete set of specifications which
along with the drawings and other details are submitted to the
owner for his final stamp of approval.
A yard is then selected to build the yacht and the naval
architect works with the yard's engineering department to
develop all of the detailed shop drawings required to build the
finished yacht. During this phase the naval architect
represents the owner to be sure the fabrication is sound and
that certified materials are used. He checks equipment to
verify it is installed in a manner which will result in a yacht
that needs a minimum amount of maintenance. At the same time he
is working with the owner (or interior designer) and the yard
to select interior fabrics, furniture design, floor coverings,
ceilings, lights, bath fixtures, galley equipment and literally
thousands of small detail items.
Usually when the yacht is finished, the naval architect
supervises the sea trials before the yacht is handed over to
the owner.
How are computers used on yacht design?
Today computers are the tool of the trade, just like drawing
boards and drafting instruments were in past times. They allow
the naval architect to handle a voluminous amount of data in a
very efficient way. Computers make some parts of the design
process easier; however, they do not replace the artistic eye
and experience of the designer. After the approximate size of
the yacht has been determined and the mission profile studied
so that the desired speed and range are known, the computer is
used to predict the resistance so that the horsepower can be
determined to select engine(s). Computer modeling lets the
naval architect have the freedom to enter design parameters and
to vary widths, weights, bottom angle for best results. In a
matter of minutes the computer calculates very accurate and
useful data to help determine the hull shape and powering
requirements.
The 3d modeling programs that have been developed in recent
years are very advance and allow the designer to illustrate the
yacht’s styling, rotate to any angle and color as
desired. They allow exact fit of the interior and systems
saving a large percentage of the time required for
construction. With few exceptions all of the industry
uses one of these programs to develop the basic and production
designs.
Next the computer is used to develop hull lines and to fair
those lines to very small tolerances. The accuracy is greater
than necessary; however, it gives the builder exacting
information from which he can establish his own tolerance.
Fiberglass molds made from computer lofting require less time
and provide fairer surfaces than pencil drawings where the
builder can be off by as much as 1/8th of an inch just by
measuring to the wrong side of a pencil line. In metal
boatbuilding the computer numbers are often fed directly from
the computer to the shipyard computer program where the steel
or aluminum plate is cut from the numbers thus eliminating any
need for costly and time consuming full size hand layout of
frames and plates. In composite construction, plugs and molds
can be digitally cut using 3-D shaper cutting machines.
After the lines have been put into the computer, the naval
architect has all the hydrostatic calculations displayed in
front of him in seconds. He knows the displacement of the
yacht, the center of buoyancy, the pounds per inch of
immersion, prismatic coefficient and other important data. As
the designer makes minor adjustments to the lines, the computer
recalculates all of the hydrostatics instantly.
When building to class or USCG approved Charter Yacht, the
hydrostatics must meet strict guidelines and computer models
are created to simulate various conditions of loading and
creating damage conditions according to the possibilities
allowed by the hull subdivision. This very important function
is all too often forgotten by builders and on occasion by
designers that are not familiar with the established practices
for safe construction. Due to this negligence many yachts have
been lost, some on their maiden voyages.
Later in the cycle, the propeller design or propulsion
system design is determined by special computer programs
developed specifically for the type of vessel being
designed.
What is model testing and what does that do for
you?
Model testing is the physical towing of a scale model of the
exact hull shape of the proposed yacht, through a water tank
with a fully instrumented carriage that measures the motion and
resistance of the scale model hull. This data is then
translated to give a very accurate prediction of how the actual
yacht will handle and precisely what hull drag can be
expected.
One should also conduct rough water tests to provide the
acceleration information necessary for the naval architect to
refine the hull lines to the point where the yacht can meet the
speed desired and provide a comfortable ride for the
passengers. It also provides the information necessary to
develop hull structure which will withstand the punishment
heavy seas can hand out.
FRYCO has conducted tests at many of the best model basins
in North America and Europe Normally we conducted over 100 test
runs at various displacements, longitudinal center of gravity,
different bottom configurations and several sea states. The
results almost always yields some interesting and useful
information to increase performance or comfort.
Why do you have a model of the exterior of the
yacht?
These works of art are called "styling model" and they are
recommended for every new design. Even with computer drawings
and color illustrations some clients prefer a three dimensional
sculpture so that they can view all angles and be sure that the
styling is exactly what they want. Even though a styling model
is costly, we feel it is certainly justified. A five to fifteen
thousand dollar investment to know what a five to fifty million
dollar yacht will look like amounts to pretty cheap
insurance.
A styling model is also very helpful to the designer to
arrange the necessary antennas, radar and other support
equipment in an aesthetically pleasing way.
On large complex jobs it is not uncommon to build interior
models of details or even the entire yacht. Although they can
cost thousands and take time, it is another worthwhile modeling
tool.
Why design the yacht to class?
The world outside of the USA would never ask this question,
since elsewhere all yachts over 24m (79 ft.) in length are
built to class in most places; however, in the States it has
been our practice for many years to depend on the designer and
builder (often the same person or firm) to do a good job. With
the event of ISO standards and ISM code requirements, plus the
gradual tightening of yacht entry requirements by many
countries, if you plan to do any international cruising, it is
certainly recommended that any yacht more than 24m (79 ft.)
long be built to class.
The classification society sets standards for the
designer/builder to follow. The requirements are not tough and
are well thought out for the safety of the passenger. Some
rules regarding hull openings, railings and doors are ignored
by many; however, those are the guys that have never been
caught out in really bad weather.
Class assures minimum hull strength and subdivision needed
for a major investment. The bankers and insurance companies
appreciate the fact that an independent expert has reviewed and
approved the plans and inspected the construction. The annual
survey by the Classification Society is an audit for the owner
by an independent agency to assure that the crew is on their
toes and that all necessary maintenance is performed to keep
the investment in safe operating condition
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