Trimming Sails with Telltales
When you’re sailing, the difference between “getting there” and “getting there faster” often comes down to a few six-inch strips of ribbon.
These are your telltales – visual clues to the invisible forces of the wind on your boat.
While a fluttering luff tells you that your sail is depowered, telltales tell more of a story. They give you clues as to how the air is moving across your sail.
If you want to master foresail trim, you need to learn the clues.
1. The Golden Rule: Move Towards the Flow
Whether you are steering the boat or trimming the sheet, the most intuitive way to remember how to react to telltales is the “Move Toward” rule.
On a foresail (like a jib or genoa), you have telltales on both the windward (inside/closest to the wind) and leeward (outside/away from the wind).
If the windward (inside) telltale flutters: It’s “starved” for air. You are either steering too close to the wind (pinching) or your sail is too far out.
The Fix: Turn the tiller/wheel toward the correctly streaming telltale (bear away) or pull the sheet in.
If the leeward (outside) telltale flutters: the air is stalling. You are either steering too far off the wind or the sail is over-trimmed.
The Fix: Turn the tiller/wheel toward the correctly streaming telltale (head up) or ease the sheet out.
When both sets of telltales are streaming straight back, you have laminar flow—the holy grail where the wind flows evenly across both sides of the sail like a foil, creating maximum lift and speed.
2. Using Telltales to Set Your Lead Position
Most of us know how to adjust the sheets, but many forget the jib car. The position of the car on its track effects the “twist” of the sail. This comes in useful for trimming all three sets of telltales along the luff (top, middle, and bottom). The wind speed at the top of the sail is likely to be different to the speed at the foot.
As you head up toward the wind, watch which telltale starts to flutter first:
Top Telltale Flutters First
This means the top of the sail is too “open” or twisted out. The sheet is pulling back more than down.
Adjustment: Move the jib car forward. This changes the angle of the sheet to pull down on the leech, closing the top of the sail.
Bottom Telltale Flutters First:
This means the bottom of the sail is too “open” and the top is too tight.
Adjustment: Move the jib car aft. This pulls the foot of the sail tighter and allows the top to “twist” open.
Tip: In heavy winds, you actually want the top telltales to break slightly before the bottom ones. This “twist” allows the top of the sail to spill excess power, keeping the boat flatter and easier to handle.
3. In the Real-World
Trimming isn’t a “set it and forget it” task. Wind direction and strength will shift, so your telltales will be in a state of flux.
Upwind Beating
When sailing close-hauled, your sail is usually sheeting in tight. Use the telltales to steer. Try and keep the windward telltales just on the edge of “dancing” (lifting slightly). This ensures you are pointing as high as possible without losing speed. If they drop or flutter wildly, you’re pinching; bear away slightly to regain power.
Reaching
On a reach, your course is usually set, so use the telltales to trim. The trimmer should be “playing” the sheets. If the windward telltale lifts, pull the sheet in. If the leeward one stalls, ease it out. It all depends on whether you are racing or cruising as to haow often you do this.
Summary
While a fluttering luff tells you that your sail is depowered, telltales offer more information. They tell you exactly how the air is moving across the surface of your sail. If you want to master foresail trim, you need to learn to speak “their language.”Ribbon”.