ILCA Sail Telltale Placement

Sailing a precise angle upwind is paramount for good boatspeed. Angle is critical to ensure optimal VMG, airflow over the sail, and water flow on the foils. Without the proper angle upwind, your boat reduces in performance dramatically and suddenly. Without correct telltale placement and correct use of those telltales, it can be difficult to maintain a perfect angle.

Being skilled at reading the water and wave angles helps keep you on track. Understanding gusts and lulls and how they affect the direction of the apparent wind also helps. But most importantly, good telltale placement helps ensure your sail is working properly. It is important to understand what to look for on your telltales.

When asked, most people who visit ISA give the incorrect answer when asked what the telltales should be doing. Sticking them on in an arbitrary position is also incorrect. After regular use, the luff of the sail can become very deep, and the telltales may need to move slightly closer to the mast to give the same visual cues. Too close to the mast, and the separation bubble will make them dance too frequently.

Ideal placement

Measure from the foot of the sail and all the way at the front of the luff sleeve.

Full Rig: 31 inches up, 23 inches in; and 60 inches up, 17 inches in.

Radial: 31 inches up, 20 inches in; and 53 inches up, 20 inches in.

4.7 Rig: 27 inches up, 19 inches in; and 47 inches up, 15 inches in.

What to look for

Ideal telltale behavior has the upper set in the green and sometimes yellow zone. The bottom telltales are mostly blue. The trick is to sail the exact angle where the upper windward telltale flicks forward slightly at the crest of the waves.

Bigger swell is confusing because boatspeeds may increase so much from surfing the backside of waves that both telltale sets are in the yellow or even red zone for moments. It is important to recognize whether this is only momentary, because correcting by bearing away could result in a stall while climbing the next set of waves.

In flatter or choppier conditions, being diligent with your telltales to sail perfect angles can result in huge speed gains. We recommend looking at them every 5–7 seconds, and every time you feel something change. A loss in power does not always require a change in direction.

Keep your sail happy, and sail fast.