Hydrofoil Trimarans in New Zealand : Attn Gary Baigent

A recent posting on the list for the International Hydrofoil Society (IHS) included a photo (attached) of a nice-looking hydrofoil trimaran by David Knaggs of New Zealand.

In trying to find out more about this boat, I came across a very interesting history of foilers from a New Zealand perspective :
http://www.crew.org.nz/NEWS/Special Interest/History of Foilers.html .

The article was evidently written by Gary Baigent, who contributes to this list, and whose boats Flash Harry & Misguided Angel are also described.
The article gives dimensions for length & overall beam of these boats, but I would like to find out more details (weight, sail area, foil dimensions, etc.).
Of course, I am most interested in the smaller boats that are more nearly comparable to my own (Broomstick).

I am especially intrigued by the descriptions of how well Baigent's boats go to windward on the foils & would like to find out more about their performance (racing, speed trials,etc.)

I'm hoping Gary will see this & answer, but I would also like to hear from anyone who has more info on these great foilers.

 

Kiwi hydrofoil tris

Hi Doug
Here is some data and jpegs on the kiwi foilers.
Speaking about 30 year old Flash Harry, (6 x 6 metre) the boat is very basic and because of that, is light, two people can pick the complete boat up fully rigged, haven’t weighed it, I’d say 75 kgs. The float dagger asymmetric foils are relatively small (305 x 39mm chord to thickness and based on NACA65-412 and only a metre long overall with 300mm bury through the floats) - because I wanted a boat that would lift off only in stronger winds (12-14 knots) and in lighter conditions the foils, being small, would not drag too much. The float foils are set at 40 degrees and at 3 degrees angle of attack and they slope forward a few degrees to try and halt cavitation when passing through waves, only partially successful in larger waves. The boat will crash violently but jumps up to fly again almost immediately. Deeply immersed inverted T foils would be better. In flat water and stronger gusts the boat is stable and very fast. The rudder blade is 250 x 32mm and based on 64012 drawing 700mm below waterline. When I say based on, I built them myself out of stripped wood with glass and carbon reinforcement in the hard point areas, not done in a laboratory and over the years they have dinged rocks and torn into the sea bottom at high speed, been repaired and rubbed down so many times that the dimensions will not be as originally drawn.. The inverted T is asymmetric and has a total span of 640mm tapering from 140mm at blade bottom to 40mm at the tips – and is fixed at zero angle of attack. No flaps because I believe, no matter how superbly they are built, the slot will drag, but I could be wrong here. The engineering design genius David Knaggs would think differently. In ultra light conditions, below 1 knot, my mate’s Finn will sneak away from Flash Harry but once there is two to three knots, Harry is faster – and of course a lot faster as the wind increases.
The boat will fly going to windward in 12-14 knots wind and fly higher as wind increases, fantastic fun and points high. In strong gusts it will gently bear away (if you don’t move the helm) while accelerating. I let it do that because helm movement slows the boat.
Regards
Gary

 

Kiwi hydrofoil tris

More jpegs

 

Float section

Gary,

Very interesting boat.

What is the float cross-section itself based on?

 

Thanks Gary-and Doug!

 

Thanks Gary,

Looks like you put a lot of hard work into this & the results are great! I'd like to encourage you to submit photos & info to the Photo Gallery of the International Hydrofoil Society (www.foils.org), where a lot more people will see what you've done.

Here's a couple more questions:

1-Was it sailed singlehanded, or with a crew of 2?
2-Can you estimate the all-up sailing weight, including crew.
3-What was the total sail area?

Thanks again

 

kiwi foilers

hi Doug
I realize I didn't label the jpegs so it is a bit unclear what images relate to what boat. The black and whites are mostly David Knaggs designs and as I mentioned, the guy is a brilliant designer/engineer and has the rare talent of creating something aesthetic as well - usually uncommon with boffins and perfectionists - that is just my opinion of course, not inflaming anyone I hope. His foiler is the white boat with the folding foils - my boat Flash Harry is the red one - there is also a colour jpeg of my 11 x 11 metre foiler Misguided Angel too. This boat has been altered so much recently I have changed the name to Groucho Marx.
The two wing mast cross section b&w's show the difference between Harry's and Dave's foiler.
The Knaggs foiler is 5.5 metres long x 9 metres overall beam, including foils. Mast height, I don't have but looks around 8 metres, sail area is 16.4 m2, una rig, displacement with single crew is 222 kgs and Bruce No. 1.7 approx. The reason I have his figures is because he sent them to me for my self published book "Light Brigade - the NZ school of yacht design" (updating at moment) - but I haven't seen him in years, or know his address.
Flash Harry was launched earlier than his boat and is no way as refined a design, both of them are approaching 30 years age though - said in a quiet voice......... "how's that Bladerunner Moths?"
Flash Harry's mast height 9.1 metres, sail area including wing mast: 18.5m2, displacement one crew: 145 kgs, Bruce Number 2.
You are more interested in the smaller boats Doug, so we'll leave Groucho out of this - has been posted before anyway.

 

Hi Gary,

No wonder Flash Harry performed so well : 6 meters long, 145 kg. total weight, & 18.5 m^2 sail area !

The hulls must be very light, especially since the large wing mast must weigh a fair amount itself. What materials & construction methods did you use?

Your book sounds interesting. Please let us know when it is available.

 

kiwi foilers

hi Doug
Flash Harry's mast: it is the fatter one in the two b&w mast section images - built in 3mm tensioned ply skin over 4mm ring frames and 4mm I beam with carbon reinforcing here and there, mostly between hounds and mast spanner - weighs 20 kgs with all rigging and is 23 years old now. Original wing mast was larger chord and much heavier, at least twice as much and came from a quite famous kiwi B Class cat named Boadicea designed by Keith McKinnven. Before the Tornadoes arrived Boadicea cleaned up all the B Class races, which was quite healthy in terms of numbers here in NZ until the Tornadoes took over. Harry used to crash regularly with Boadicea's mast mainly because of the rigs' COE being so high, because with the new/now old light one the boat flew earlier and didn't load up the leeward foil and float as much, a basic really.
Harry's hulls are built of similar dimensioned materials sheathed in glass and some foam and kevlar bulkheads in loaded areas - tensioned ply is still a very good lightweight method even in this day and age.