Doug, if you check through Fred Monsonnec's Foilers site, you'll find some more material on Dave Knaggs' foilers. The wand system he invented came maybe two decades before the wands appeared on Moths and the like. Here is some stuff from Light Brigade, you've probably read it before but others here may not of:
Another who caught the flying boat affliction was David Knaggs, an ex-Great Barrier Express sailor who knew about speed under sail. He designed and built a set of high aspect ratio foils and mounted them in aeroplane configuration (stern steering) on a Paper Tiger catamaran in 1985. This Flying Tiger was similar to the UK designer Hansford’s Mayfly, but differed in that the Knaggs’ platform had the extreme high aspect ratio, deeply immersed main foils mounted at 35 degrees dihedral (Mayfly’s and Flash Harry’s were at 40) and were set at a high angle of attack, originally at 7 degrees then later altered to 3.5 degrees, (Mayfly’s were at a shallow 2 degrees) – high angle equals high lift but also retains high drag, so a compromise has to be worked out on fixed foils. On Flying Tiger these deep foils set at 7 degree angle provided an early lift off in light winds and gave a soft and cushioned ride through waves; Knaggs calculated everything regarding his design, engineering and construction and built all the components to perfection. He describes his first sail:
“On setting the foils for the first time in calm waters and about 10 knots of wind, I was surprised to find the boat taking off so soon, despite the Paper Tiger’s small sail area, as the mainsheet was trimmed in on a reach. As the boat accelerated and climbed higher, the most striking impression was the silence and complete lack of any impression of power, despite the building apparent wind strength. Every gust caused the boat to fly higher, in marked contrast to the lee bow down of a catamaran at high speed. In more than 12 knots of wind, a takeoff while sheeted hard in on a close hauled course, was easy. Provided speed was kept down by luffing, the boat would fly to windward with most of the leeward foil immersed, the leeward hull just touching the wave crests and the weather foil mostly out. Lateral stability picked up strongly with extra heel in gusts; the waves passed unfelt.”
However he was plagued with the boat crashing at high speed (above 25 knots) – in spite of the acute forward rake of the foils that theoretically halted ventilation; this occurred on any point of sail except going to windward. Even different foil designs and varying numbers of ventilation fences did not improve this crashing situation. So after taking developments to conclusion on the surface piercing foils on the catamaran, Knaggs turned to the trimaran/aeroplane configuration for his new design – a boat he drew in 1986: 18 feet long and including the angled inverted T foils set outboard of the floats, 30 feet wide ( 5.5 x 9 metres) – an elegant, low and wide craft. He built a wing mast that bent sideways when rotated to flatten the mainsail as speed increased.
Deep camber was required for power at low speeds as no headsail was carried, but once flying the main had to be flattened. Adjustments needed to be automatic so the new foils were combined with a sensor (in appearance two foils per side) mounted outboard on a neatly designed mechanism that actuated a shaft set inside the strut – this altered a small flap on the foil trailing edge and this provided more or less lift and kept the boat flying at a regular angle. Knaggs warned: “You must keep everything simple. If you’re not careful you can find yourself going berserk with complex answers that just load the boat down with junk. But this was a revelation. Now I could scream down the face of a wave without worrying about the foils washing out or the boat burying.”
Corely, Mokihi's foils were the normal asymmetric daggers set at around 40 degrees angle through the floats. I've got some other shots so will hunt them out.
![Au5VQSpCIAEmU59[1].jpg](/data/attachments/62/62673-a08e736968316e1ba2a94993aa7fd4bf.jpg?hash=oI5zaWgxbh)
