Telltales make sail trimming and steering easier on a sailboat. Telltales provide information about flow on the sail, so it’s best to keep the information simple by placing the a few telltales at key locations. Telltales on the leech of the sail should generally be made of nylon and telltales at the luff should generally be made of wool yarn.
Where Do You Put Tell Tales On Your Laser Sail ?
We recommend 3 sets of tell tales, 2 at the luff and on that streams over the window of the sail, the one over the window helps in case there is extreme glare and the leeward telltale isn't visible. Anywhere in the bright yellow circle will work pretty well on a laser sailboat.
How Do You Use Telltales ?
On the laser it's important to always have the leeward tell tales streaming when sailing on a reach or upwind. Sailing "By the Lee" is often the fastest route downwind on a Laser, this is when the flow is going backwards from the Leech of the Sail to the Luff, the tell tales will often indicate reverse flow.
For Upwind sailing, the windward tell tales should be streaming back or flipping slightly. If either the leeward or windward tell tales stall, it's indicating that the flow on your sail has stopped and you'll have decreased or no lift.
So to summarize, the Leeward tell tales are the most important, they should always be streaming and if they're not, you need to head up into the wind. The windward tell tales should be streaming back with the occasional flutter.
The same principles can be applied to any sailboat, on a jib for example, you may have good flow on the bottom of the jib and stalled flow at the top which tells you that you need to adjust your jib settings. Jibs usually have 2-3 sets of tell tales at the luff at low, mid and high points. This way you can make sure the whole jib is powered, or spill some power when the boat is overpowered.