Tuesday, May 22, 2012

A math error

Just out sailing a test version of that Melges I saw the other day. It is Qyvs beautiful virtual Melges 24. Such a nice build. Easy to sail and very stable, - or so it seemed. I started with loads of smooth upwind sailing. Lots of easy tacks in 7 m/sec. Sooo nice.
Qyv's Melges beating
I still think she tacks just a little too slow. In a real Melges 24 the time from thought to completed tack is no more than five seconds. I mean, when I say "and tackiiiing, and up", then the tack starts on "and" and it ends on "and". And we all climb to windward on "up". Then comes the accelleration, I know, but swinging over to the new course is fast with boats that sit on the water, not in the water as is the case with more classic designs.
Going down!
Anyway. After all this tacking, I needed to get back to Tradewinds, and that's when it all started to go wrong. I decided to hoist the gen. All smoth still, but then I gybed, and all of a sudden the thing started rotating like a mad around the mast foot or something. It was a very weird experience. That's one thing a real boat would never do.
Comming up?
All the way around it rotated. Apparently at a steady rate. I clicked everywhere. I tried all sorts of commands. Sheeted out. Sheeted in. Nothing helped, until I took the sails down and moored. Finally it stopped.
Hanging in there...
Me, - all dizzy... calling Qyv. I started by saying the Melges made me dizzy, and she already knew what I was gonna say next. Turns out there was a math error somewhere... probably in a denominator. We all know how bad that is. It explodes. Next time I go sailing, I'll bring a friend from the bomb squad.

Thank God for waterproof mascara.


  1. Oooooh, I had a similar experience on my prototype boat. I was on a dead downwinds run and didn't notice the boat was gybing. I thought it might be a borked sim crossing.

  2. At least, you haven't had math errors in your wind forecasts. our forecasts been reading 14 knots. But everytime we race, we get 1.4 knots. Even William Air (Heir!) of Temptation has been faster than we, and he certainly got a better start.

  3. Doc, the beauty of virtual sailing is that 1) The sun always shines and 2) We set the wind to whatever suits us today. No forecast needed. (And there's more :-)

  4. That 360 forward loop issue was appear too on Extreme40 proto many time ago.
    Qyv solved as soon as were noticed.
    It is just a calculation on pitch forces when some bearing it is passed spi hoisted.
    When must be collapsed start forward looping…
    …but just a temporary issue, stay calm and thanks for info.


  5. :) actually it's an error in the sped curve.
    When plotted on a graph the down wind curve actually ends before it hits 180 degrees.
    When it does this it returns a "null" to the equation, NOT a zero, that's when it starts flipping.
    Sometimes you can get out of it by turning the boat but usually you have to moor and restart :)


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