We spent probably about 40% of last year's 523 mile Tybee 500 running as high and tight as possible with the spinnaker. I will attest that the loads are quite high - most of the crews hands (including mine) really paid the price. The truely grueling fact was that the spinnaker was adding a lot of drag for the power it generated - we were getting about an extra .2 knots out of it for all the work going into it...but we were racing!
Did you run a doubler on the spin sheet to ease the loads. We've found this really helps on crew fatigue when carrying the kite high on distance races. We tied a pigtail to the clew of the kite with a carbo block on it and tied a stopper knot in the end of the spin sheet. When you want to deploy the doubler you draw the stopper knot back from the pulley to a hook attached to the shroud adjuster (or on top of your spinnaker turning block on the hull).
nah...I don't think Carl would have had enough patience for me to go to the low side to cleat it...he and I share similar focus levels. Running so high, I wonder if with 2:1 if I could react fast enough to a collapsing kite.
Re: Blade F18 video
#68846 03/13/0602:59 PM03/13/0602:59 PM
If you take a look at the beautiful job that Performance Catamarans of Santa Ana, California did on the new Nacra 580, you'll find that a kick up centerboard, that has a proper foil shape, can indeed be self sealing with no added gaskets. Pictures of the Nacra 580 with kick up centerboards
This centerboard seals the trunk when it is fully retracted and it also seals the trunk when it is fully extended.
Flashback in time: Check out my April Fools Post from 2003:
A Nacra Formula 20 CB is the centerboard version of the F20 boat that is based on their new F18. The hull shapes are very similar to the newer Nacra F18 but a bit larger. They are narrow, have a very fine entry, tall plumb bows, and a super-cool ultra thin walled chromium-alloy (chromolly) super strong and lightweight mast that has better flex characteristics than other current aluminum or carbon fiber masts.
The centerboards are high aspect ratio eliptical shaped foils that employ a new centerboard gasketing system that provides a near perfect seal in all the centerboard trunk that is not occupied by the long slender foil. When the boards are lifted half way up, they swing so far aft that the center of lateral resistance is moved significanlty aft and thus provides a superior resistance to broaching.
That daggerboard is a bit to short with too long a chord for my taste. The sealing part of it could use some adjustment to fit the hulls properly But kickup daggers would be great on a distance racer, no reason to worry too much about what you can hit with them. The extra weight added to the kickup mechanism can probably be re-gained as you dont have to reinforce the daggerboard well and bulkheads around it as heavily. I like it a lot! Just need a working and robust mechanism. Have you tought about starting a fortune-telling business Gary? Seems like you are plenty succesful at it, or is your talent limited to beachcats?
Pardon my french here but what a non-informative post that turned out to be. Look at it was stated :
A Nacra Formula 20 CB is the centerboard version of the F20 boat that is based on their new F18.
Both info elements in this sentence are just plain non-sense. It was actually just a centreboard version on the Nacra 5.8; that is even reflected in its name. It DOES NOT comply with F20 rules; it is not heavy enough. So that info element was non-sense as well.
The hull shapes are very similar to the newer Nacra F18 but a bit larger.
Not really, the hullshapes are more like the old nacra's; the N5.2's, N5.5's, N5.8's and even N5.7's, then the nacra F18.
They are narrow, have a very fine entry, tall plumb bows,
What is narrow on a catamaran. I think the hulls to be rather medium in the way of narrowness. And it doesn't have a plumb bow like the Inters. Tall ? Well the Nacra F18 has tall bows the nacra 580 doesn't. At least not more then its predessor 5.8 and other nacra boats of that time frame.
and a super-cool ultra thin walled chromium-alloy (chromolly) super strong and lightweight mast that has better flex characteristics than other current aluminum or carbon fiber masts.
Right ! All other designers are still using wooden masts on their boats right ? And clearly carbon wing masts are inferiour to this pretty standard tear drop shaped mast. Talking up your product is one thing but still is more then a little over the top is it not ?
The centerboards are high aspect ratio
The N580 centreboards have an aspect ratio of 2 (the width fits 2 times in the wetted length); see provide pics.
As comparison :
F18's daggers aspect ratio are between 3 and 4. Nearly double that of the N580. A-cats daggers are close to ratio of 4. Even the old Nacra 5.8 (predessor) had a daggerboard aspect ratio of 2.4 = 20 % more then the new one.
But we call these new dagger "high aspect ratio" !
When the boards are lifted half way up, they swing so far aft that the center of lateral resistance is moved significanlty aft and thus provides a superior resistance to broaching.
Please all catamaran sailors that suffer broaching on their boat raise their hands.
Ofcourse broaching is a monohull problem. It is linked to the heeling of the boat and the weatherhelm that is caused by the centre of effort being suddenly moved far out of line to the single daggerboard as a result.
I rest my case now.
Last edited by Wouter; 03/14/0606:20 AM.
Wouter Hijink Formula 16 NED 243 (one-off; homebuild) The Netherlands