Since the invention of modern wings, around 80 years ago, many have recognize the superiority of wings as the most efficient means of transforming wind energy into a force. Luckily the Wright brothers did not fit a Jib and Main sail to their first flying machine, otherwise we might not have the travel opportunities the jet age as enabled. Wing sails have constantly proven to be the most effective propulsion system being fitted on some of the fastest sail boats in the world like Stars and Stripes 88, Yellow Pages Endeavor and the C-class cats.
Unfortunately, adapting a wing’s unique form to boats has always been a challenging and daunting task. Sails existed long before man-made wings and finding ways to make wings on boats practical for everyone has long eluded designers. Current wing sails have a number of drawbacks that make them unsuitable for general use and therefore appear only on radical, special purpose boats. One particular problem stems from the need to have a wing that is self tacking, hence many of the wings built have multi-element symmetrical sections. The symmetrical sections are only slightly more efficient than a traditional sail plan but come with a large problem payload. For the slight gain in efficiency, these types of wings are expensive to build, very complicated, cannot be adjusted for all conditions and are difficult to store.
BUT… It has just been a matter of time before someone figured out how to use wings on a boat and hence the Dynawing concept was born. Our soft wing sails usher in a new dawn on the ancient art of sailing and this leap forward in technology will do for sail boats, what the jet engine did for aircraft. The Dynawing brings wind powered boats out of the sail age and into the Wing Age, this is going to be a great time to go sailing… The Dynawing changes the double surfaced, soft wing sail playing field and brings wing sailing to the general boating user in a completely practical form. The Wing Age is now possible on just about any wind power craft used today, water, land or ice. Welcome to the Wing Age ! Why have we had to wait so long ? To many, the only “experience” with wings in sailing is what we have seen or read about the multi-element wings frequently on radical one off racing machines. These are the wings used in C-class cat racing or aboard the Stars & Stripes cat that caused such a stir when it defended the Americas Cup in 1988. Other attempts at making soft wing sails have ended up more like “streamlined sails”, than wing shapes used in the asymmetrical DynaWing and DynaRig wing sails. The reason for the lack of previous success is that these “streamlined sails” have both surfaces of their wings close in length to each other. These wings have limited lift capability as they develop very little “Bernoulli Effect” over their surfaces.
The other major stumbling block is that the joints between the multiple elements on hard wing sails develop a huge amount of drag. These rigs are only slightly better than a traditional sail and most only have an L/D (lift to drag ratio) of approximately 12:1. This is hardly a great improvement and not really a practical trade off for all that hardware above your head. The asymmetric wing is so clearly superior to the other types of wings and sails on the market, that it is surprising that we haven’t seen or heard more about them before. The main roadblock to the general introduction an asymmetrical wing sails like the Dynawing, has been the fact that they have historically been built “hard”.
Hard asymmetrical wings have given notable performance on extreme machines like Yellow Pages Endeavor, Extreme 50, and Techniques Avancées. The problem with hard wing sails is they can not be tacked without a tremendous effort or the help of major mechanical machinery on-board. Hard wings are also tremendously difficult to store and this has made them impractical for any sort of general usage. The best effort we have seen so far was the Walker Wing Sail, but it cannot be reefed and the firm is not longer trading as far as we know. Dynawing solves the hard wing problem… Welcome to the Wing Age!
After several years of extensive research and 15 years of head scratching, Robert Hobbs made a breakthrough in the world of sail power. Bob found a new way to combine the three basic components of a wing to produce a soft wing sail that can be used practically on any wind powered boat.
Over a similar time period and unknown to Bob, Greg Johnston and his brother Patrick were working on the same problem in Perth, Australia. The two brothers came at the problem from a sailors point of view rather than an aerodynamic angle of attack. Both came to the conclusion that soft wing sails are a great way to improve the performance of wind powered vessels.
In the summer of 2001, the Dynawing partnership discovered the aerofoil inducer blade, invented by Gordon Ross of Powerfoil, Ltd. This aerofoil inducer blade, is the quantum leap forward that Dynawing has been searching for, in its mission to commercialize the soft wing sail concept. The Powerfoil aerofoil inducer blade is the key technology that brings soft wing sailing out of the “nice idea, but very expensive” phase and into the world of commercial reality, where affordable double surface sail products are now possible. The Powerfoil aerofoil blades are cheap to make, very light to use, do not require a tapered mast and are extremely reliable in service. The aerofoil blades allow a soft wing to use readily available, pultruded carbon rod batten technology, replacing the need for using custom, tapered batten technology.
We think that the use of soft wing sails is well over due in the sailing industry and we hope they will help turn around the performance picture of today’s sail boats. We think that the use of soft wing sails by sail boat designers can go some way toward stemming the tide of pleasure boaters defecting to power over the use of sail. Welcome to the Wing Age!
How do soft wing sails work?
Imagine a round, fat and fixed mast as your starting point, acting as the leading edge of the wing. Then wrap a double surfaced, fully battened, sail around this thicker than average mast, and fix the sail to the mast so that it cannot move.
If you leave the mast in one position and allow the sail to fall off to leeward, the windward batten will pull straight and the leeward batten will bow out. This will create an asymmetrical air foil shape. The further out to leeward you let the wing sail out, the thicker the aerofoil gets which produces an efficient lifting, asymmetrical shape, just like an aircraft wing.