tell tales and camber stripes

Thread starter #1
In the Laser main there are tell tales behind the luff. To the best of my understanding tell tales are only used in these position on fore sails like genuas and jibs, because the mast causes eddies and vortices that disturbe the flow too much and mains generally are fitted with tell tales on the leach, at the position of the battens.
How does this work out in the Laser (why no tell tales on the leach, but near the luff).

I am also considering putting camber stripes on my practice sail, to improve on my understanding of the influence of vang and luff tension. Any recommendations on placement of these stripes?



Active Member
The forward and leech telltales do a completely different job. The forward ones are a steering help, while the ones on the leech are for estimating twist.

For the steering telltales, it doesn't matter much whether there's a mast or just a wire at the luff, the fundamental aerodynamics is still the same. The point is to have them near the forward edge of the whole sailplan, no matter how many sails there are altogether.

In the Laser, upwind twist is not really a tuning variable, and when running, you don't really need a telltale to show the correct leech tension, and the flow is turbulent anyway. A leech telltale might be useful on a reach, but most people don't bother, as today's courses often have no reaching legs at all.

More reading from my local sailmaker: WB-Sails - Aerodynamics

Camber stripes are redundant on a crosscut sail. On a radial cut, you might try them at 1/4, 1/2, and 3/4 heights; on a Laser sail that corresponds pretty closely with the battens.