18ft Skiff

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Current Specifications
Churchills flying 2005-09-17 1280x983.jpg
International 18' Skiff Churchills on Sydney Harbour
Crew 3 (triple trapeze)
LOA 8.9 m (29 ft)
LWL 5.49 m (18.0 ft)
Beam 2.0 m (6 ft 7 in)
Hull weight 155 kg (342 lb)
Main & Jib area Unlimited, typically
26–32 m2 (280–340 sq ft)
Mainsail area 9.28 m2 (99.9 sq ft)
Spinnaker area Unlimited, typically
61–73 m2 (660–790 sq ft)
RYA PN 675

The 18 ft Skiff is considered the fastest class of sailing skiffs. The class has a long history beginning with races on Sydney Harbour, Australia in 1892 and later in New Zealand. The boat has changed significantly since the early days, bringing in new technology as it became available. Because of the need of strength, agility and skill, the class is considered to be the top level of small boat sailing. In Australia this boat is called the "Aussie 18" due to its inherent connections to Australia. It is the fastest conventional non-foiling monohull on the yardstick rating, with a score of 675,[1] coming only third after the Tornado and Inter 20 (Both multihulls).

History[edit]

The 18 ft Skiff has come a long way in more than 100 years of continuous development.[2] From heavy boats carrying a crew of ten or more, to today's high-tech, light-weight, high performance design. Parts of the history of the early days of skiff sailing, between 1892 and 1945, is found on the pages of the Australian 18 Footers League.

The modern 18 ft Skiff[edit]

Today there are two modern hull designs racing. The "International 18" is based on a design by Iain Murray, while the B18 was designed by Julian Bethwaite. The Australian 18 Footer League allows only the International 18, with the annual JJ Giltinan International Trophy contended with the one design Murray hull. The European Class Association allows both designs to compete against each other.

Although there are differences in the sailing aspects of the two designs, their measurements are very close, with a waterline length of 18 ft (5.49 m) and an average beam of 6 to 8 feet (1.83 to 2.44 m), not including the wings. With wings the maximum beam is 14 feet for the "International 18" and 18 feet for Open 18's sailed at Sydney Flying Squadron. When the boat is dry it should weigh not less than 375 lb (170 kg) including wings, foils (centreboard and rudder) and the number one rig of sails, spars and ropes.

In the 1980s and 90's wings were widened to the extreme - some boats having maximum beam of 29 feet. Such wings proved unmanageable, with the crews too much on the brink of disaster for consistent success.

While true 18' skiffs have no sail area or mast height limitations, the limit that the 18 footer League has specified for their one-design sub class is a maximum mast height of 33 ft (10 m), truly powerful on an 18' hull. The entire rig, which supports sails with unlimited area, is currently controlled by three trapezing crew members.

The boat will plane upwind starting at a true windspeed of about 8 knots, depending on sea conditions and off the wind can reach speeds that doubles the true windspeed. This is possible through the very high sail-carrying power to total weight ratio, which is above 30% with the no. 1 rig and approaches 40% with the no. 3 rig (for reference, a 30% ratio is needed to plane upwind and a 10% ratio is needed to plane at all. Most cruising boats have a ratio under 5%).

In Australia, there is a fleet of approximately 20-25 18 Foot Skiffs at the "League" club in Sydney. Sydney's other traditional 18 Foot Skiff club, the Sydney Flying Squadron, has a small fleet and there are several boats in the state of Queensland. In New Zealand the class flowing is smaller but reached its zenith in the 1970s when most designs were by Bruce Farr.

The 18 ft skiff is not without its dangers. The high speed makes it hard to handle and requires extremely fast reflexes and a broad awareness of your surroundings in order to anticipate changes. Major accidents can occur with inexperienced and experienced sailors alike.

The 18 ft skiff is currently one of the fastest monohulls on the water. With its massive sail-plan of over 100 square meterres on the no. 1 rig and three crew members on trapeze it can outperform nearly every monohull on the water. It combines extreme speeds with an element of danger and is thought by many to be one of the biggest spectacles in sailing.

Each year the JJ Giltinan International Trophy is contested on Sydney Harbour to decide the de facto world champion of the class. Typically the event was dominated by Australia and occasionally won by New Zealand, but in recent years entrants such as the USA's Howie Hamlin have taken out the title, displaying the classes growing international appeal.

Design Considerations[edit]

The first flying 18 footers were either carvel or clinker built clinker planked with multiple steam bent frames. Cotton sails were used and spars were solid wood. The crew number varied according to the wind strength, often with a boy carried to bail out water. Initial designs were conventional displacement shapes with emphasis on narrow waterlines. In the early 1950s The Sydney boats put emphasis on carrying large extra sails down wind called ringtails. These were set outside the main with light spars top and bottom.They were carried in addition to spinnakers. In very light conditions watersails were carried under the main boom.The most revolutionary boat of this period was the lightweight New Zealand Result which was cold moulded with 2 skins of Kahikatea glued together and nailed to lightweight Mangeao bent steamed frames every 21 1/2 inches. At 6 ft 3inches Result was narrower than the conventional boats but still had the same full bow sections typical of the displacement style boats. Result had spaceframes of wood to support the mast and centreboard. In any breeeze over 10knots it was faster than any previous 18s because of its planing ability. From this period increased knowledge and understanding of hydrodynamics and aerodynamics, coupled to the availability of plywood and reliable waterproof glues saw dramatic changes. Clinker and carvel construction was dropped and glued up hollow pear shaped masts became standard. By the late 1960s a greater understanding of the science behind planning saw hulls made with increasingly less rocker, very fine forward with very flat aft sections. Once trapezes were introduced the number of crew dropped to 4 by the early 70s and then to 3. Designs became wider, especially aft. As speeds increased so did capsizes, so an effort was made to install built in buoyancy and some self draining capabilities with transom flaps, venturi floor drains built in tanks, especially forward and false floors.

Foils became more hydrodynamic, especially after the availability of tank test models. Wood was dropped as a foil material in the 1980s and replaced by stiffer synthetic materials such as fibreglass then kevlar and carbon fibre. By 1970 hollow wooden spars were replaced by tapered aluminium of much smaller section and lighter weight. These in turn were replaced by much stiffer and lighter carbon fibre masts in the 1990s. Sail area got progressively larger especially when wings were added. This enabled small crews to sail with extremely large sails in stronger wind strengths. As most boats were sponsored they could have multiple rigs to match the wind strength. Other modern features are carbon fibre prods (bowsprits) supported by bob stays, dolphin strikers and bow struts. This enabled quicker setting and dropping of the large downwind sails. Huge spinnakers could be set quickly by having halyards geared by miniblocks running internally in the mast. Dacron sails were replaced by much lighter stiffer less porous material such as mylar plastic. Weights of the bare hulls dropped quickly when New Zealand designer Bruce Farr, using his experience in Moth and Cherub designs used thin 3mm ply supported by multiple lightweight stringers and stiffened with tissue fibreglass. These were quickly followed by foam and fibreglass hulls first designed by Russell Bowler. Bare hulls weigh 120 lbs but are very strong with the use of carbon and kevlar to locally reinforce mast steps, centreboard cases, chain plates and wing attachment points. Rudders were placed 500mm aft of the hull to give more control in extreme planing conditions when only the last few feet of the hull was in contact with the water. These innovations have made the skiffs very fast but very expensive to build. In New Zealand this has seen the class decline dramatically as top sailors were attracted into the more conventional one design Olympic classes. By 2005-8 experiments were carried out largely in Switzerland using hydrofoils based on successful experiments with the Moth class. The experiments showed foiling was possible in flat water or small waves after the distance between the 2 foils was improved. Experiments showed that a conventional spinakker slowed the boat down compared to sailing with main, genoa and or genakker. With very wide tube and net decks up to 29feet wide modern boats can carry very large powerful squareheaded mainsails that have the controls to twist the head of the main in gusts to depower. Flying 18 footers can now regularly exceed the actual windspeed when planing on all points of sailing.

The Historical 18’ Skiff[edit]

In Sydney and Brisbane Australia there has been a revival of the early days of 18’ skiff sailing. Replicas of famous 18’ skiffs from the period of 1930 through to 1950 have been built using original techniques, including wooden hulls and spars, gaff rigs, several-piece spinnaker poles and unrestricted sail area. These boats race under the rules of the Australian Historical Skiff Association, which bans wings, trapezes, cleats for controlling ropes for the mainsail, jib and spinnaker, and most of the other modern equipment which makes sailing easier.

The class has proved very popular with former sailors of modern 18’ skiffs who, to quote a class champion John Winning, are looking for a challenge because “the modern boats have become too easy to sail”.

The historical 18’ skiffs have a crew of between 6 and 9, which often leaves an opportunity for visiting sailors to have a ride.The AHSSA website listed below has more details.

At present the class is raced out of the Sydney Flying Squadron in Sydney and the Brisbane 18 Footers Sailing Club Inc. There are also bi-annual challenges against the New Zealand 18’ Kauri-Clinker M Class.

Notes[edit]

  1. ^ "Dinghy and Catamaran Database". Noble Marine Insurance Brokers. Retrieved 22 August 2012. 
  2. ^ See section 16.10 of Bethwaite, Frank (2007). High Performance Sailing. Adlard Coles Nautical. ISBN 978-0-7136-6704-2. 

See also[edit]

  • The following book provides a comprehensive description of technological developments up to 1993 that have been incorporated in the 18 ft Skiff and other high-performance boats: Bethwaite, Frank (first published in 1993; new edition in 1996, reprinted in 2007). High Performance Sailing. Waterline (1993), Thomas Reed Publications (1996, 1998, and 2001), and Adlard Coles Nautical (2003 and 2007). ISBN 978-0-7136-6704-2.  The book also covers the history of the 18 ft Skiff and of high-performance sailing in general, as well as the sailing techniques required to achieve high performance.

External links[edit]