History of Sailing Yacht Masts, Rigging and Sails: 1900-Present day.
by James Gilliam

Part IV: Windsurfer Technology.
(Continued from Part 3)

Windsurfers:

     Windsurfers were developed in the 60's by 2 southern Californian surfers in the 60's. The first windsurfers hit the water in 1968 and since then they have become very popular. Some say there are more windsurfers on the planet than and other sailing craft. This is due to the small cost, simplicity and small size.

     The general design of the windsurfer, or sailboard as it used to be known, has changed little since its original design. The changes have come about in the development of new materials and new manufacturing techniques. The way in which a windsurfer rig is different to a dinghy or yacht rig is through the use of a universal joint connecting the mast to the board. This means that the rig is held up by the sailor and the rig is able to tilt in any direction. This enables the windsurfer to be steered by tilting the rig.

     Modern windsurfers have carbon-Kevlar masts and fully battened laminated sails with a large amount of aft mast rake. These rigs are used with high tensions along the leech; this gives the most efficient foil shape and keeps the sail more stable. With these new technological developments in windsurfer technology they have been able to set the wind-powered water speed record of 45.34 Knots.

Figure 12

     The latest development in windsurfer technology is the "DynawingTM". Developed in the late 90's with the aid of computer design and testing a highly efficient sail has been produced. This is a so-called soft wing sail; it is more efficient than a traditional sail as it conforms to a better aerodynamic shape and virtually eliminates the drag induced by the mast. This results in greater lift and reduced drag.

     There are not very many avenues for further development of windsurfer technology. There will be however gradual improvement in the materials and manufacturing techniques that are used to make windsurfers. Future changes in windsurfers could come in the form of some of the same laminate technology that has been used in dinghy and yacht sails.

Running Rigging.

Running rigging introduction:

     At the beginning of the 20th century the choice of running rigging was very limited. Hemp rope and other natural fibres were all that was available. In the 30's Nylon and other man-made fibres were being developed. This led to a revolution in the rope industry. Man made fibres were less prone to environmental damage, less stretch, lighter, stronger and less water absorption. These new fibres enabled rigs, which could be tensioned up more it also reduced weight aloft. Since the introduction of these man made fibres in the first half of the century technology has moved on and the properties of the ropes have been gradually improving.

     Modern rope is usually an exotic fibre, Kevlar is commonplace, sheathed a flexible rope fibre. The fibre core is for load carried and the sheath is in place to protect the internal fibres. It is common practice aboard high performance dinghy's (such as 18ft skiffs) to remove the sheath from the rope and to use only the load-carrying core. This reduces the weight aloft and decreases the pitching moment of the mast. The drawback of this is that the rope will need to be replaced more often and the rope must be checked for damage more often. There is a vast amount of different types of rope available today. Each has its own properties, which suit certain uses. For instance for a halyard a lightweight low stretch rope is needed or an anchor rope where a cheap material is used and also floats in water.

Overview of principle properties of rope materials:

Nylon:

• Most elastic of all fibres
• High strength and stretch
• Minimal strength loss when exposed to sunlight
• Ideal for use where stretch absorption are important, such as in dock and anchor lines

Technora:

• Highest strength Aramid fibre
• Very low stretch
• Subject to fatigue if cycled over small radius
• Does not creep under normal loads
• Black version has superior resistance to UV degradation
• Ideal for low stretch rigging, such as halyards

Polyester:

• Low stretch fibre
• Very good abrasion resistance wet or dry
• Excellent weathering characteristics
• Spun polyester is fuzzy, filament polyester is smooth
• Good choice for running rigging requiring moderate to low stretch, good durability and a nice feel
• Often referred to as Dacron, a DuPont trade name

Polypropylene:

• Light weight and no stretch
• Floats
• Very susceptible to UV degradation
• Melts under high friction

Spectra:

• Very high strength and very low stretch
• Light weight; will not absorb water
• Low melting point, susceptible to friction
• Very slippery
• "Creeps", gets longer under sustained load
• Ideal for low stretch running rigging requiring light weight

Vectran:

• Liquid Crystal Polymer fibre
• Very high strength
• Extremely low stretch
• Zero creep
• Low water absorption
• Good resistance to "Flex Fatigue"
• Ideal for low stretch running rigging on competitive race boats and mega-yachts

Conclusion.

     There have been many major developments in rig technology over the last century. The most significant being the transition from natural materials to man made materials. The development of aluminium rigs, polyester sail-cloths and polyester ropes have proved to be the most important developments of the 20th century, they have enabled rigs to be mass produced making sailing a more affordable pastime. The developments have come about from the shift in use of sailing rigs, which occurred in the early part of the century. The use of sailing rigs for the transportation of goods and fishing declined rapidly and in its place recreational boats began to appear and the need for speed came about, leading to the developments discussed.

     The benefits of all the developments, which have happened in the sailing and windsurfing industry, is that there is now a vast number of options available to builders and owners. The decisions on what material and construction to be used for all aspects of the rig are based on cost, performance, reliability, durability and a host of other factors.

     From this report it is clear that new technology's take many years to be used extensively in the sailing industry. New materials which are developed need to become cheap enough to warrant their use. Without that happening then the existing rig which is by far the most common in dinghies, an aluminium mast with Polyester sails and stainless steel twisted strand rope, will take a long time to be superseded in terms of use.

     I believe that major new developments in rig technology are going to be a long time coming. The technology that has so far been developed has plenty of room for improvement. There is a theoretical limit to how efficient the rig is as a whole. The advancements in technology in the last century have brought designers closer to this maximum value of efficiency.

References and bibliography:

Principles of Yacht Design - Lars Larsson and Rolf E Eliasson 2nd edition 2000 By McGraw-Hill Companies

Boat Data Book - Ian Nicholson 4th edition By Adlard Coles Nautical

Yachting World - May 2001 pg 78-82

Yachts and Yachting - April 13th 2001 pg 52-58

Sailing Today - February 2000 pg 44-48

Web sites used:
http://www.aerorig.com/
http://www.uksailmakers.com/encyclopedia.html
http://www.marlowropes.com/yachting/
http://www.ronstan.com/marine/
http://www.contendersailcloth.com/products.htm
http://www.doylesails.com/design.htm
http://www.neropes.com/pleasure_marine/
http://www.jclassyachts.com/
http://www.windsurfer.com/
http://www.pyacht.net/
http://www.northsails.co.uk/
http://www.rigshop.com/nitronic.html
http://www.vectranfiber.com/fabric_samples.html

Notes:
[1] Taken from http://www.rondal.com/p_ni_33.htm
[2] Taken from http://www.pyacht.net/cgi-local/SoftCart.exe/online-store/scstore/h-dyform_wir e.htm?E+scstore
[3] Results taken from Yachts and Yachting

Introduction | Mast Materials and Manufacturing | Standing Rigging Materials | Sail Materials and Technology | Windsurfer Technology