Another Big Canting Keel Boat has Blown-up its Mast

[rob denney]

G'day,

I sold the Outleader kite to the boat (AAPT, a 66'/20m ultra light sled, with fixed keel) before the Sydney Hobart a couple of years ago. As the owner wanted to keep it as a surprise, he did not order it until the last minute. Consequently there was only 2 weeks to practise with it to figure out how to handle it and optimise it. The kite was 380 sq m/4,100 sq' which was near enough 3 times the size of the previous biggest kite Kiteship had built.

The kite launched and flew pretty much as expected, but there were some stretch issues which had not been expected which limited the power available. There was barely enough time to figure out the cause and fix it. While we were working on this, the boat got embrolied in a ratings dispute, the breeze the week before the race was very light and the forecast was for an upwind race, so the owner decided against fixing and taking the kite to Hobart. He consequently rubbished the kite and sold it to a cruising cat owner who is undecided what he wants to do with it.

As it happened, the first day was downwind, the top boats fell apart and AAPT finished 2nd. Lots of what ifs unresolved.

What was clear from this was that the kite imparted no heeling forces on the boat, lifted the bows (a big problem when running under spinnaker) and was very easy to set and trim (the kite was hoisted, set, trimmed and lowered without any winches being wound). The owner would not let us drop it on the foredeck (which is easier than dropping a conventional spinnaker) as he was worried (without cause, in my opinion) about the flying lines cutting his pbo rigging. Consequently, it was dropped in the water and pulled in over the stern, which was a nightmare.

The publicity from successfully flying the world's largest traction kite was enormous (the sponsor valued it at $300,000) and was only matched by the negative publicity when the owner very publicly decided not to use it in the race. This and the out of hand banning of kites by the powers that be dealt Outleaders a crippling blow, although I have since sold a few to cruising boats and will be flying one on my solo Transpac proa which I will be launching soon.

A big kite would be a handful for a solo sailor if anything went wrong, but no more so than a wildly flogging spinnaker. They would certainly solve the broaching, nose diving and heeling problems as well as putting no strain on the rig. Oulteaders will fly at 90 apparent and can be flown across the sky on downwind courses, which is a much more efficient way of building apparent wind than sailing the boat at an angle to the course. Beats me why everyone is not using them as primary down wind sails, and in smaller versions as back ups for when the mast falls down.

Chris' comment on carbon for Joe average is not quite correct. The problem is that Joe average wants what the race boats have, which is dictated by the rules.

A cruising boat carbon mast could currently be built for less money than an alloy tube, supported by wires, if the boat was designed for it from the beginning and the costs were worked out over the life of the rig. A race boat mast would be even cheaper in comparison. Carbon prices are starting to fall again, so they will become even cheaper. The key is to use an unstayed mast.

These are a bit like the kites. They make far more sense than what is currently used, are initially more expensive, but have far fewer maintenance and wear issues. They are built by innovative small companies with no money for advertising and lobbying against the riggers, sailmakers and asociated vested interests and are frowned on by the top race guys (perhaps due to having to learn new skills?) so no one further down the food chain is interested.

Regards,

Rob

[Pericles]

From BBC. http://news.bbc.co.uk/1/hi/england/h...re/7153238.stm


Last Updated: Thursday, 20 December 2007, 07:29 GMT
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Navy assists stranded yachtswoman
Dee Caffari
A helicopter is on stand-by to take Dee Caffari to safety
A Royal Navy warship has sheltered yachtswoman Dee Caffari overnight after her vessel lost a mast in high winds in the Bay of Biscay.

Dee Caffari, 34, from Gosport, Hampshire, was on the final leg of the 4,300-mile single-handed Transat Ecover B to B race from Brazil to France.

Her 60-ft yacht was damaged in severe weather 300 miles from the finish.

[DGreenwood]

You cannot design these boats not to break. You can sit down at a table with the best engineers in the world and ask them to think for ten days and come up with rules...your not going to make it. In modern yachting, failures are very much in the hands of the crew. As a designer I have a huge amount of responsibility as far as the safety of the boats, but the crew are as responsible to make sure that they back down when they need to back down.
Juan K. speaking about the Volvo 70s

[Guillermo]

Very interesting post, Rob Denney.
Would you please let us know more on your kite propulsed solo Transpac proa?

Cheers.

[rob denney]

[quote=Guillermo;176590]Very interesting post, Rob Denney.
Would you please let us know more on your kite propulsed solo Transpac proa?

Cheers.

G'day,

http://www.harryproa.com/SoloTranspac/Solitarry1.htm

The hulls and decks are built (KSS, very quick) but cannot be joined until the mast and beams are built and fitted. The telescoping mast, boom and beams start after the Xmas holidays. We obviously missed the Hobart this year (no carbon for the mast and beams), but are vaguely hopeful of being in the water for Brisbane Gladstone at Easter. This is getting increasingly unlikely due to pressure of other work. Worst case scenario is I miss this Transpac, but have plenty opf time to prepare fro the next one.

There is not much about the kite in the write up, but I have been playing with launch and retrieve procedures on my half scale version of the solo boat. A water driven line handler has made a huge difference and I am now looking at ways to launch it using 3 strings rather than 4. As my kite (40 sqm) is twice as large as a Tornado spinnaker, there are a few issues which will not be present on the big boat, but I figure if I can handle the monster on the little boat, a more sensibly sized one (90 sq m) on the big boat will be no sweat.

Any questions, please ask.

regards,

Rob

[Guillermo]

Thanks, Rob.
So, your boat still has mast and main. Would you consider kite propulsion only?

Cheers.

[rob denney]

Originally Posted by Guillermo

Thanks, Rob.
So, your boat still has mast and main. Would you consider kite propulsion only?

Cheers.

G'day,
Not at the moment. The current generation of kites do not have high enough L/D ratios to go upwind better than a conventional sail. There are a lot of very smart peope working on this, it is only a matter of time.

Regards,

rob

[Roly]

Now Skandia. A "mild" broach at 22 knots (boat speed).