Course of Cup design
Roger Marshall assesses how the rating rules have shaped the Cup yachts over 100 years
r'ntil 1983, the America's Cup was
a symbol of American supremacy. Although it has always been an
B event which builds up to fever I I I pitch then fades into obscurity, its
successful technological developments have e\'entually filtered down to the general sailing fleet to become an everyday part of production designs.
In 1870 Cambria competed against 23 other schooners and was defeated by Magic. James Ashbury. Cambria's owner, challenged again in 1871 with Livonia. This time the Americans lin-ed up four vessels ready to race him and the match was won by Columbia and then by
Sap-plio when Columbia was disabled. Ashbury
pro-tested, with the result that any subsequent challenger only met one deferider, the racing format we know today.
The rating rules have always played a very interesting part in influencing design. The schooners of the early races gave way to sloops with the inception of the Cubical Contents rule in 1880. This rule calculated the volume under the sheerline and led to shallow-draught, beamy boats with a huge spread of canvas. Under this rule the Canadian boat Atalanta was easily defeated by Misciiiefm 1887 When one of the boats taking advantage of this rule sank at her mooring, drowning all on board, the rule was changed. Dixon Kemp proposed what eventual-ly became the Seawanhaka Rule, taking into ac-count length and sail area. Its final form has survived to be incorporated, though slightly
changed, in today's Intemational Offshore Rule.
2
L was measured on the LWL. This rule led to the first noticeable burst in development.
The first match under this rule was in 1885 between Puritan, of shallow and beamy design, and Genesta, deep and narrow, in line with British design practice. The launching of
Gloriana in 1891 moved yacht design in the
direction of the metre boat style. A new Nathaniel Green Herreshoff design, she had a fin keel, 4,00011^ of sail, was 46ft on the waterline but 70ft overall. She won eight races in eight starts and Herreshoff, to defend the Cup, designed and built no less than six defenders from 1893 to 1920. He drew
Gloriana's successor, the centreboarder Vigilant. Vigilant was criticised during trials,
for the new ideas she encompassed. She fac-ed Lord Dunraven's G.L. Watson-designfac-ed
Valliyrie II in the 1893 match and won three
straight races. Lord Dunraven challenged again with another Watson yacht, Valiiyrie III, a boat close in design to the American defender. Both boats sported long overhangs, long bowsprits and deep keels. The match ended acrimonious-ly when Valkyrie fouled Defender.
1899 saw Sir Thomas Lipton's first challenge in a boat that pushed the limits of the rule.
Shamrock was 129ft overall with the unlikely
combination of manganese bronze plating under the water and aluminium topsides. She raced
Columbia. All the time yachts were getting
longer. Shamrock, designed by William Fife, was 2ft Sin short of the 90ft they could be on the waterline whilst Columbia was 2in less than this maximum length. Shamrock led in many of the light air races but in heavier winds
Col-umbia crossed the line first and won the series. Constitution and Independence, specially built
for the 1901 challenge, lost in the trials to
Col-umbia but not before Independence's
scow-shaped hull and lightweight construction had shown surprising bursts of speed. Her con-struction was so light that she leaked and the hull twisted as she sailed. The match was yet another victory for New York YC but led to another challenge from the sporting Sir Thomas Lipton. Sliamrock II, designed by G.L. Wat-son, while extremely fast, was defeated due to lack of preparation and experience. She was one of the first boats to be tank tested.
Reliance was the biggest boat ever built for
the America's Cup. At 89ft 8in on the waterline, 143ft 8in overall with a sail area of 16,160ft^ and a mast of about 190ft, defeated Shamrock
III, another Fife design, and ushered in a new
era. She was a true extreme yacht: thinly plated, with a towering rig and long overhangs designed to cheat the 90ft LWL limit. Just five knots of wind would heel her enough for
Reliance's sailing waterline to increase from 90ft
to 130ft due to her 54ft of overhangs. Thus the Universal Rule came into being:
Rating = L x SA 5 Disp
This is the forerunner of today's rule. Lip-ton challenged again in 75ft wateriine boats.
Shamrock IV was the first America's Cup boat
designed by Charles Nicholson of Camper & Nicholson fame. She was in the mid-Atlantic when Worid War I was declared and eventually lost to yet another Herreshoff yacht, Resolute, when the races were finally held in 1920.
It was in 1924 that the American and British discussed rules and scantlings and the Thames measurement rule gave way to a 'scientific rule' developed by R.E. Froude which eventually became thé International Rule we have today. By 1928 the American Universal Rule had been adopted for boats over a 76ft waterline or J Class boats, while the British International Rule was adopted for boats under this length.
C O N T I N U E D OVERLEAF
Olin Stephens, doyen of tiie designers. R i g h t , Dame Pattie in 1967
The J Class saw major design changes: the Bermuda rig replaced gaff-headed mainsails, alloy masts replaced wooden spars and winches proliferated and moved below deck.
The boats had now become stripped-out rac-ing machines and, with new sail developments, were much faster than earlier yachts. Parachute spinnakers, double and triple headsails and Quadrilateral (i.e. double-clewed) jibs came into use. Improvement in headsails and hull design made the 1937 Endeavour II one of the big-gest J boats yet built. Olin Stephens and Starl-ing Burgess worked together and, with a large amount of tank testing, produced Ranger which ran away with the series and advanced the cause of scientific tank testing along the road to acceptability.
With the advent of Worid War I I , it was not until 1958 that the Cup was challenged for again and this time it was in 12-metres: boats approx-imately 65ft long, weighing 55 to 60,0001b; less than one-sixth of the weight of a J boat and diminutive compared with the likes of Shamrock
III and Reliajice.
The Americans held trials with four boats and it was the S&S designed Columbia which went on to defeat David Boyd's Sceptre, a British boat criticised for her rounded bows and exaggerated pitching. A feature of this challenge was the new Dacron sails and the open cockpit of
Scep-tre which was copied by later Twelves until Courageous almost sank.
Four years later in 1962 the AustraEans came to Newport with Alan Payne's Gretel, a faster yacht than the defender Weatlmiy designed by Philip Rhodes. However, lack of experience prevented them winning.
The next step in the evolution of the 12-metre came with Constellation in 1964. Another S&S creation, she had a bendy boom, a mast light enough to bend to suit the sail
shape and a very stripped interior. Once again the defender beat the challenger, the Boyd-designed Sovereign from Britain.
The biggest advance in design came with Olin Stephens' masterful Intrepid. Her rudder, with a trim tab at the trailing edge to reduce leeway and develop more lift, was removed from the trailing edge of the keel and placed at the end of the waterline. The rudder was prefaced by a large bustle — called a kicker — which had the effect of moving the quarter wave further aft and rnaking the boat appear longer in the water. Wetted surface was also reduced by almost seven per cent making the boat poten-tially faster in light winds. In her first series in 1967 Intrepid beat Warwick Hood's Dame
Pattie 4:0. Dame Pattie weighed
approximate-ly 61,5001b while Intrepid weighed about 56, 5001b. The lighter boat had better acceleration in most conditions.
The 1970 series saw a Britton Chance re-design of Intrepid beating Gretel II while Olin Stephens produced Valiant, the logical next step down the path found by Intrepid. Valiant, however, had too big a bustle and was too large altogether. Olin learned from this and produc-ed the superb Courageous for 1974. The 1970
series was marred by some rating interpreta-tions and decisions which annoyed the Austral-ians. When Chance re-designed Intrepid he moved the rudder stock aft six inches and fil-led the space with fairing strips. Thus for displacement purposes the boat still had a waterline length of 45.5ft but an actual waterline of nearer 46ft. Alan Payne's Gretel II had a real wateriine of almost 46ft making her 1,8001b heavier.
Major changes were set for the 1974 challenge. Built in alloy Courageous and
Southern Cross had a significant weight
advan-tage over earlier boats in that the hull struc-ture of wooden boats weighed about 15,0001b; the remainder of the weight was in the lead keel. An alloy boat, on the other hand, had a hull structure at that time of about 10,0001b and the remaining weight in ballast. This had the effect of making the alloy boat stiffer. Mariner, another defence candidate, took the
In-trepidAMant thinking to its logical conclusion.
The problem with Mariner was that the model in the towing tank allowed the water to be fooled into filling the space behind the chop-ped off stem making it seem as if the boat were actually larger than it really was. However, when the tmncation was scaled up to full size, it became impossible for the \vater to accelerate to such a speed that it could rush into the void and make the full size boat seem larger and hence faster Unfortunately, when Valiant was changed to the same configuration, any refer-ence point was lost until she sailed against
Courageous in the NYYC regatta in Long Island
Sound. After a disappointing summer Mariner was sent back to Derecktor yard where she was rebuilt, arriving back in Newport in time to be eliminated in the July trials. That left the way free for a tremendous battle between
Courageous and Intrepid. Courageous was
even-tually selected when she won the last race of the series by 41 seconds. She defeated Ben Lexcen's first Twelve, Southern Cross, by wide margins in the races for the Cup. Soidhern
Cross was a much bigger boat weighing about
61,0001b against Courageous' 56,0001b.
Courageous' weight came in for acrimonious
debate after the series when it was found that Shamrock I I (left) and Columbia after tlie start of the first race in 1967
Shamrock IV, 1920 Shamrock V, 1930 she had actually been lighter than the rule
allowed. Apparently the boat was about 1,1001b lighter than declared. But the total weight cut out of the keel was more than that due to the ruling that cockpits must now be completely watertight. This and the lighter weight meant that Courageous' waterline had to be shorten-ed to make the displacement requirshorten-ed by the rule. A total of a few inches was removed from the bow and the boat was ready to compete again in 1977.
In 1977 htdependence, Enterprise and the revamped Courageous were pitted against
France I, Gretel II, and Sverige. On the design
front the Americans were running scared after the towing tank got the blame for the Mariner debacle. Independence was a largely intuitive design from Ted Hood, sailed by him and at-tempting to use only Hood sails. The S&S designed Enterprise, always said to be a slow boat was, in fact, an almost exactly half way step between Courageous and the boat to come in 1980, Freedom. The only boat which had anything different in design was Pelle Petter-son's Sverige which had pedal-driven winches. Almost by default on the part of the designers the 1977 series had developed into a battle of the sailmakers: Hood versus North, Kevlar and Mylar versus Dacron and nylon. Sail technology moved forward. Finally it was Ted Turner driv-ing Courageous who beat the Lexcen and Valentijn-designed Australia 4:0.
Dennis Conner is widely credited with turn-ing the America's Cup into a full time profes-sion and for the 1980 series he used Enterprise and the new Freedom. Ranged against him were
Clipper, built out of the remains of In-dependence, and the old warhorse Courageous.
AÜ of these designs were close to 45ft on the water and weighed around 56,0001b. At this time, none of the defenders had been tank test-ed and it was rapidly becoming apparent that the zenith of hull design had been reached.
Australia was soundly beaten by Freedom
driven by Conner. The consensus in 1980 was that the future Cups would be decided by the sailmakers.
That all changed when Lexcen's Australia II appeared on the scene. Her radical keel marked a departure which enabled other things to be done with the design. The wings became a ma-jor controversial issue as soon as the boat started winning.
Designers have known that a smaller, lighter boat will accelerate faster than a larger boat, for many years. In America's Cup racing where the boats move close to the same speed this is a distinct advantage. The Deed of Gift for America's Cup boats sets a minimum length at 44ft on the wateriine. The LWL also governs the minimum weight at about 51,0001b. However, until Australia II there was no possi-ble way to get enough stability in a 44ft waterline hull for sailing in the heavier winds. The practical lowest length evolved at about Intrepid, 1967
45ft. Courageous, Enterprise, Freedom,
Defender and Libetiy were all close to this size. Australia II, on the other hand was about a foot
shorter on LWL and on the dimension L . As L is part of the rating formula and D and F re-mained close to conventional values, the designer was able to increase sail area, mak-ing the boat faster in lighter winds. Also reduc-ing L reduced the wetted surface by a few per cent improving light air performance even more. In my opinion i t was only because of the ex-perience of Conner and his crew that the Cup series wasn't a walk over for Australia II like
the challenger trials had been. •
