I was reading this thread concerning whether people use telltales or not. I remembered while watching the DVD entitled, ‘The Catamaran Sailing DVD’, that Ashby commented about looking at his sails while racing A-class catamarans. Well, I was bored so I went and wrote down what he said concerning looking at telltales. For what it is worth, here is what Ashby had to say on that DVD;

“It is very much a professional reflex but I am always looking at the sail to see what it is doing. I think it comes from me being coached at a very young age to look always at the sails and look at the telltales on the sail to see what is happening. I do it without thinking. Yesterday, when we had the camera on the side, it is amazing to see how many times I look at the sail. Particularly, downwind it is important to look at the sail and make sure you are getting the maximum performance out of the sail. It is very easy to be sheeted too hard and stalling the sail, and it is also very easy to be open and be loosing power.”

Anyway, I thought someone might find it interesting what a sailor of Ashby’s caliber concentrates on while sailing.

Cheers
Bob
boatless at present

Drag is not always directly related to the creation of lift. Seperation can and will also occur in area's with insignificant lift productions. Especially in light winds where the energy enclosed in the boundery layer may well be insufficient to traverse the pressure increase that is present near the leech. On this theoretical ground I reject the line of reasoning followed, that in addition to the experiences I gained so far in real life sailing.

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Think about it. Why do you suppose modern sails have gone from low apect ration to tall, skinny, high-aspect ratio sails?

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Because high aspect ratio sails have a lower Cd (drag) coefficient for the same Cl (lift)coefficient, however at the expenses for being more easily stalled and more sensitive to trim. And because in light winds their is significantly more wind further away from the surface, the is more kinetic energy in higher wind layers. This tops out at about 10 meters above the ground. In 5 or less knots of wind it is not unusual to experience twice the windspeed at the top of the mast then a 1/3rd the mast height.

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Because the leech of the sail is not nearly as productive as the area that creates the lift.

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This is simply an wrong way of looking at things. The luff and leech parts of a sail interact directly with eachother and combined result in a given lift and drag situation. Removing either one will completely alter this setup. Example; you can seperate both regions as if they are completely independent of eachother. Remove the leech part and the luff segment will not at all act the same as before and the lift produced will collaps.

Therefor a properly working leech region is key, just as the luff part; its role is however different from the other segment. Pretty much the luff segment is most concerned with creating high lift by creating large suction zones, while the rear part is actually the part that reduces drag to such a level that the Cl/Cd ratio is efficient.

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Jet wings are much more high-aspect say than a DC 3.

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And this example can be totally put around to combat your comments. Sailboats are much more like a DC3 then a modern high velocity (0.9 Mach) jet airliner. Ergo we should look more to the DC3 then the modern Jetliner. And as a matter of fact we do. Our mainsail aspect ratios are much more comparable to the DC3 than of the modern airliners.

But more so the operating conditions of the sailboat mainsail are still well removed from the DC3 Operating conditions which is still MUCH close then those of a modern airliners. Looking at these aviation examples is therefor of very limited use.


Anybody interested in more will do well to read bethwaites book for starters.

Wouter

Yep that is what I'm finding and the leech tell tales are always the first indicators that I'm loosing speed and power and that is why I value them so much in these conditions.

Wouter

Folks,
May I suggest that this all gets down to the perspective of the individual.
I naturally over sheet so I need leach tell tales to keep me in check.
However I have also sailed several seasons and done quite well with no tell tales at all.
When you have nothing the only indication you have is the feel of how the boat goes thru the water. At the end of the day that is what it is all about anyway.
I expect that both Rick and Randy have so much experience that they don't need to be told when they are overssheeting either because they don't do it or because it is bloody obvious to them so they don't need to be told.
I personally believe that our varying levels of experience give us different perspectives and so I think that if you are a beginner take a check on the leach tales ,if you have experience in the magnitude of Rick and Randy. Gedt rid of the distraction and focus on other important issues of trim.
jUST AS A PERSONAL OBSERVATION:-
i probably sail better without any tell trails but feel more secure when I have them to check. But is this sitiuation I relax and don;t continue to look for extra speed.
Just a personal observation!

This understanding has always worked for me.

I only use tell tales sailing uni-rigged off the breeze and then only if I can't go wild. The 430 is not like other uni-rigged cats I've sailed, in that it works best with the traveller centered and the sheet on hard in anything above 5/8ks.
With the kite up I'll need them until I find the best traveller position which goes with a folding spi leading edge.

That's how I'm seeing it presently but things may change as I become more familiar with kiting on a cat.