DESIGN
PHILOSOPHY It's
no
secret... boat owners are tired of paying big bucks to go sailboat
racing in something that does not deliver on performance.
That,
combined with constantly trying to fill crew numbers, is forcing a lot
of people out of the sport altogether.
The VG-Mount Gay 30 is the affordable solution. It's not only
a
high performance grand prix racer and a versatile yacht to compete at
the local club level, but also the latest generation of boat designed
to the Mount Gay 30 Rule. The boat has a unique dual purpose, catering
to short handed offshore sailing with water ballast, and
around-the-buoys inshore competition with a full crew.
The underlying theme of this project has been one of meticulous
consideration to the sailing criteria of the boat. This
included
an extensive research and development program by Van Gorkom Yacht
Design. This effort, coupled with custom quality construction
by
Boston Boat Works, has delivered a champion fleet racer to the
marketplace, not soon to be outclassed by the competition.
RESEARCH &
DEVELOPMENT To
aid in the
design process of the VG-Mount Gay 30, Van Gorkom Yacht Design
undertook an unprecedented research and development program.
This
program was comprised of three phases: model development by way of a
complete parametric analysis; a one-model tank test series; and a post
analysis and optimization to formulate the final set of lines for the
production female tooling.
A complete parametric analysis based on a range of 30 footers with
similar performance criteria to the VG-Mount Gay 30 was made to develop
the lines for the tank test model. The lines were created using an
advanced lines-fairing program facilitating the creation of a truly
fair hull shape. The resulting computer model was given to
the
builders for the 5-axis milling of the model hull.
The model was built to a 2/3 scale (approximately 7 meters); the large
scale insuring the best possible results for the data
collected.
Since only one model was being tested with no keel and rudder
variations, it was imperative that the resistance curves being
generated be as realistic as possible. Approximately 150 runs
were made in the towing tank at various speeds, heel angles, yaw angles
and rudder angles. This information was used to create a matrix of data
that modeled the hydrodynamic characteristics of the hull
form.
This matrix was in turn used as an effective tool for the calibration
of the VPP and ultimately in defining the final hull form.
This proprietary module, written into the VPP,
allowed VGYD to simulate the same performance characteristics of the
physical tank model. This made it possible to quantify hull
variations in terms of performance by racing the variants against the
base boat in the VPP. Armed with this powerful analytical
tool, a systematic series of canoe body variations was created to allow
VGYD to fine tune the hull form resulting in what was considered to be
the best performing boat.
An extensive post-analysis was conducted to compare experimental
performance data with known performance criteria from other similarly
sized yachts (i.e. ILC30s, existing Mount Gay 30s, and the
Mumm30). In virtually every instance, the VG-Mount Gay 30
showed itself to be as fast, or faster than the competition, confirming
the speed potential of the design. This high-tech approach taken by
Geoffrey Van Gorkom has yielded a wealth of knowledge and insight into
the performance characteristics of the VG-Mount Gay 30. It not only
serves to validate the design; it translates into winning boats for the
people who sail them.
TANK TESTING
The tank testing has been an essential part of the research and
development phase of the program. It has told the designers
exactly how the boat is performing and the magnitude of the
hydrodynamic force or resistance that is generate by the hull form.
Tooling
considerations will affect the method, speed and cost of manufacturing,
and so impact on the unit price and market efforts. Tooling
must be economical, accurate within the desired tolerances, be easily
maintained and repaired, and last the required number of production
cycles.
The
model was built to a 2/3 scale, approximately 7.0 meters and 1000 kg of
displacement. Building a large model such as this has several
benefits. Firstly, the optimum weight for the dynamometer is
1000kgs, meaning the best possible results are achievable without
having to use counter balances and risk inducing extraneous
errors. Also, the greater the scaling factor the cleaner the
data will be with a higher degree of repeatability.
These
factors had a direct bearing on the overall economics of the
program. Since only one model was being tested with no foil
variations, and approximately 150 runs being made in the towing tank,
it was imperative that the resistance curves generated be as realistic
and as accurate as possible so they can be used as an effective tool
for the calibration of the VPP and ultimately in defining the final
hull form.
The
tank testing was conducted at the National Research Council's Institute
for Marine Dynamics in St. John's, Newfoundland. This
facility is regarded as one of the pre-eminent marine research
facilities in the world, boasting a 200 meter towing tank, and an
extremely accurate and fully calibrated dynamometer for the measurement
of lift and drag forces. The tank is also equipped with a
sophisticated towing carriage which travels up to 10 meters per second
and a hydraulically driven wavemaker capable of generating up to a wave
height of one meter.
The
dynamometer was designed and built by Institute personnel specifically
for America's Cup Research. For more than a year, Fluid
Thinking Pty, the design team responsible for Australia One,
collaborated with IMD in preparation for the 1995 Americas
Cup. The unique precision achieved through its use has
resulted in a physical phenomena previously unappreciated by the
international hydrodynamics community. This discovery has
intern led to improvements in the accuracy of experimental predictions
and repeatability of results for yacht hull design.
POST ANALYSIS
& OPTIMIZATION
The data collected from these experiments has allowed the designers to
calibrate their VPP, and to run a series of variants to fine tune the
resulting hull form. The goal was to create a computer model
with the same performance characteristics as what the tank test model
exhibited at IMD. This made it possible to make
minor changes to the computer model and assess those changes by running
the variants against the base boat in the velocity prediction program.
Six systematic series were
created with each series exploring different parameters such as; the
beam to draft ratio, prismatic coefficient, slight changes in the after
body, flare variations, and combinations of each. A fleet of
the best performing variants from each series was then raced in the VPP
to come up with the most optimized hull form. By making this
final analysis, it has allowed Van Gorkom Yacht Design to enhance and
optimize the performance of the boat.
The
VPP software that was be used for the post analysis and optimization
has been developed by Clay Oliver of Yacht Research International,
Inc. This Windows based program, called Winn Design VPP, is a
proven state-of the-art performance prediction tool, having been
exclusively used by the winning Team New Zealand in the last America's
Cup. Clay Oliver has an impressive history of being on
winning design teams. His portfolio includes Stars
& Stripes the 12 meter (1987), Stars
& Stripes the catamaran (1988), successful Whitbread
projects (1994), and Team New Zealand (1995).
PERFORMANCE &
RESULTS The
VG-Mount
Gay 30 has been designed for an all-out performance with a clean and
elegant hull shape, narrow waterline beam and a low wetted
surface. The freeboard overhangs aid in initial stability and
allow either crew weight or water ballast to produce a relatively high
righting moment, contributing to the boat's sailing
stability.
The bow has a fine entrance angle for windward performance and a gentle
run aft for planing ability.
One of the primary criteria of the VG-Mount Gay 30
is a strong windward performance. This was deemed necessary
to make the boat attractive to the U.S. market whose owners typically
race windward/leeward courses. This is not to say that the
off-the-wind performance has been compromised, as the VPPs show the
boat to be a strong all-round performer for both offshore and
around-the-cans conditions.
A
displacement/length ratio of approximately 112 in sailing condition (98
in measurement condition), make for a powerful and very easily driven
canoe body. The projected sail area to displacement ratio of
33 indicates a great heavy air performance and superb planing
potential. The VG-Mount Gay 30's high sail area to wetted
surface ratio predicts a superior light air performance.
Since the frictional drag on a hull, which predominates at low speeds,
is a function of wetted surface, the sail area to wetted surface ratio
of a sailboat is indicative of its performance in light air.
Where the average for a 30 footer is about 3.5, this design boasts a
ratio of approximately 4.0.
In its first two
seasons (1998 & 99), the VG-Mount Gay 30 recorded an impressive
string of performances in a number of the East Coast's more prestigious
regattas: Team
One Offshore Race - 1st in class, 1st overall; Nantucket Gold Regatta - 5th in
class;
Buzzards Bay Regatta - 1st in class; New England PHRF Championship -
4th in class;
American Yacht Club Fall Series - 1st in class; Key West Race
Week - 3rd in class; Block
Island Race Week - 1st in class.
CONSTRUCTION Boston Boat Works, under the capable
direction of well known boat builder, Mark Lindsay, bring their
expertise in building composite laminates for one- design and
performance racing sailboats to the VG-Mount Gay 30. This
design, engineered and built to the Mount Gay 30 Rule and ABS, ensures
a high level of strength and hull integrity in anticipation of heavy
offshore sailing conditions. The structural design of the VG-Mount Gay
30 makes widespread use of advanced laminate analysis techniques, and
applies them to produce a strong, lightweight, yet durable boat.
The
hull and deck are constructed of wet-preg, epoxy / e-glass laminates
over CoreCell SAN and end-grain balsa cores, vacuum-bagged and
oven-cured for a light and exceptionally strong boat. Local
reinforcement with unidirectional fibers and higher density cores is
tailored to specific load paths.An ingenious internal grid unit ties together ring
frames, stringers, floor timbers, engine bed, maststep and bunk fronts
into one integrated structural form to greatly enhance strength and
esthetics.
RIG AND SAILS The competition fractional rig from Hall
Spars has in-line jumpers and 15o
swept back spreaders. For fine tuning sail shape adjustments
there is a 16:1 backstay, checkstay controls, course/fine main sheet
controls, and runners with dedicated winches, all within reach of the
mainsail trimmer.
The spars are aluminum alloy with a
carbon fiber package option. The specially designed carbon fiber
spinnaker pole can be rigged on the mast for symmetric spinnakers, or
affixed on the deck in the bowsprit position for a user-friendly
asymmetric set. This ensures optimum reaching and downwind
performance in all conditions.
There is a high aspect ratio, large roached mainsail of 36m2 (387.5ft2). There are three
jibs, 80%, 100%, 150%, ensuring a strong windward
performance in all conditions. The 93m2 (1000ft2) 0.5oz masthead asymmetric, and
the 0.75oz 100m2
(1076ft2) symmetric spinnakers make for
a powerful off-the-wind inventory. A smaller 1.5 oz. asym can be flown
from the hounds in heavier conditions. Basic Rig Measurements
I = 11.400m, P = 12.600m, J = 3.480m, E
= 4.310m, BAS = 1.475m, SPL = 3.900m
DECK ARRANGEMENT
The VG-Mount Gay 30 deck is the perfect working platform for both
offshore and around the buoys racing. The cockpit is long and open with
ample room for crew to carry out maneuvers. Input from several world
champion racers and hardware experts contributed to the selection and
placement of hardware and control lines, reflecting the thinking of
today's best racing programs. The Harken grand prix hardware package
includes two dedicated runner winches, two primary winches, and two
self-tailing Quatro winches on the cabin house.
The
ideal layout conceived for short-handed racing also translates into a
very "cruising friendly" configuration. Leads are easily
accessible from the safety of the cockpit, and foot braces are placed
to ensure both racers and cruisers enjoy a comfortable seating position
at any angle of heel. The coach roof has slightly more than the minimum
height and area, conforming to the IMS interior volme
requirement. This provides a good working area both above and
below decks, as well as producing an esthetically pleasing profile.
The competition style tiller
steering is familiar to the racing helms-person and does not divide the
cockpit. The bridge deck, at the forward end of the cockpit, provides
an express lane for crew during tacks, keeps the cockpit clear for the
trimmers, increases headroom below, and provides some comfortable
seating when enjoying leisurely afternoon sails.
INTERIOR ARRANGEMENT
The interior of the VG-Mount Gay 30 has a very attractive and clean
finish. It is functional and well attuned to offshore sailing
and coastal cruising. In the central cabin there is a comfortable
sitting height of 1.60m (5.5ft) over a length of 2.05m (6.73ft).
There
are four fixed berths 1.9m (6.23ft in length), port and starboard, two
in the central cabin and two aft quarter berths. The galley,
forward and to port, has a sink and a one-burner stove and plenty of
counter top. There is stowage both underneath the working
space and outboard of it.
To
starboard there is a removable cooler, the top of which forms
additional counter space. There is storage lockers outboard and cubby
holes port and stbd for odds and ends. Aft of the companionway is a
dedicated nav station with a full instrument console. The mast bulkhead
separates the head from the main cabin. Fresh water capacity is 14
gals, located in a bladder tank under the galley sink. The
fuel tank, located just aft of the engine, has a capacity of 15
gal. The inboard Yanmar diesel with Saildrive unit is
immediately aft of the companionway ladder. In the forward
compartment of the engine box is a 75 amp hour battery.
FOIL
CONFIGURATION
The keel is a state-of-the-art, high-lift foil and dolphin bulb
configuration and is designed to the maximums limits of the Mount Gay
30 Rule. It has a draft of 1.95m (6.4ft) with a keel weight
of 1150kgs (2535 lbs) giving the boat a ballast to weight ratio of 50%.
This, together with movable ballast, provides the VG-Mount Gay 30 with
a powerful righting moment.
Two
keel options are available with this design. The first is the
Mount Gay 30 Class legal keel, as previously described. The
second is a "sports" keel that is 200mm (8") deeper and 225 kgs (500
lbs) lighter, essentially making for a lighter boat but with a similar
righting moment. These keel options add yet another dimension
of versatility to the VG-Mount Gay 30. The structural components of
the keel comprise of a ductile iron keel to hull flange and fin insert,
with an integrally cast lead fin and bulb. The keel flange is
faired into a recess in the hull, which provides maximum strength and
rigidity and easily detaches for trucking.
The pre-preg all-carbon rudder and rudder post are exceptionally light
with weighing only 9 kgs (20 lbs). The high lift sections of the rudder
are similar and complimentary with that of the keel foil. The
elliptical trailing edge maximizes effectiveness and minimizes drag.
Harken Black Magic rudder bearings complete the feeling of smooth and
virtually frictionless helm control. Like the keel, the rudder is
easily detached for ease of transportation.
WATER BALLAST
When racing offshore, sailing shorthanded, or just cruising, a full
range of stability is available using the water ballast
tanks.
This added righting moment gives the VG-Mount Gay 30 a marked
performance increase, and is a proven, safe and reliable form of
movable ballast.
The
system operates via an electric pump with a hand pump backup.
The pump may be brought on line at any time and takes approximately two
minutes to fill a tank. The flow controls are located in the
cockpit just forward of the traveler, providing quick and convenient
access to the trimmer. The total capacity of the port and
starboard wing tanks is 600 liters (158.5 gals), or the weight of three
and a half crew members per side.
The
plumbing of the tanks is designed to be simple, easy to maintain, yet
highly efficient. There are only three flow controls to this
system; the 3" dia. inlet/outlet gate valve, and two port and starboard
gate valves for the 3" dia transfer pipe. Two-way diverter
valves are located down below to switch from a bilge pickup, or to
switch from the engine pump to the hand pump. The gate valves are all
spring-loaded (+ in the closed position) with control lanyards leading
up into the cockpit which can be held open by cam-cleating the lanyard
in place.
Operating
the water ballast system couldn't be easier. To pump water
into the port tank, the starboard and overboard gate valves are
closed. Begin pumping until the port breather valves, located
on the shear, blow water. To dump the water ballast, simply
open the port and overboard gate valves, and the water will drain out
with gravity.
Tacking the VG-Mount Gay 30 with water ballast is just as
easy. Prior to the tack, open both port and starboard gate
valves, keeping the overboard gate valve closed, so the water will
drain down to the lower tank. The transfer, with the 3"
transfer pipe, takes approximately 30 seconds. Once the
transfer is complete, close both gate valves and tack. It's
almost like roll tacking the boat! If there is any water
loss, the new windward tank can be easily topped up with a few strokes
on the hand pump.
TRANSPORTATION The VG-Mount Gay 30 can be set up and
rigged in under two hours, and launching from a single-point hoist
takes only 15 minutes. The towing package includes a state-of-the-art
Triad Trailer, complete with electric brakes, hull saddles, and a dock
box. This makes transporting the boat from regatta to regatta
a breeze. There's no better delivery than 55mph to windward
down the highway.
