The Deceptive Telltales

Due to the high speed of the Hobie Cat, when sailing upwind the windward telltales can suggest that the sail trim needs adjustment — but that’s not actually the case.

SILVIA GUERRA, HEAD OF THE NAREGNO SAILING CENTER (AND INSTRUCTOR TRAINER FOR UISP AND THE ITALIAN HOBIE CAT ASSOCIATION), SHARES HER TECHNICAL INSIGHTS ON CATAMARAN HANDLING.

When I work with students who aren’t complete beginners, I often notice that as soon as they start trimming the sails, they immediately look at the telltales — the airflow indicators on the sails. In theory, as long as the airflow moves smoothly across the sail, the telltales should stream horizontally.

However, a beginner must first learn to trim the sail “right to the edge of luffing.” To do this, they must understand what point of sail they are on. Only afterward can the function of telltales be properly explained.

There are also situations where the standard rule simply does not apply.

For example, on an Hobie Cat 16 — or any high-performance, fast boat.

Let’s see why. But first, an important clarification: your point of sail must always be considered in relation to the true wind, not the apparent wind.

Misunderstanding this concept easily leads to confusion and mistakes.

When discussing upwind angles, we refer to the true wind. Anyone who believes a boat can sail as close as 20 degrees to the wind is greatly mistaken.

In sailing manuals, the diagram of points of sail typically shows a no-go zone of 90 degrees (45° + 45°). While some racing boats may point as high as 35 degrees, this is not relevant in a training context.

Sailing Upwind

So what happens?

A sailor steps onto a catamaran for the first time, sails upwind, trims the sails, checks the telltales — and then begins to bear away because the windward telltale is lifting too much, pointing upward, and appearing incorrect.

But that’s exactly how it should be.

If you want to sail properly upwind in at least 6–8 knots of wind, the windward telltale should stream upward — and the stronger the wind, the straighter it will stand, almost as if glued to the sail.

This happens because the apparent wind angle is much narrower than 45 degrees. The windward telltale suggests that to optimize sail trim you should bear away. However, if your goal is to sail upwind, bearing away would cost you too much angle.

On a traditional sailboat, which does not sail as fast, the difference between true and apparent wind is smaller. As a result, the windward and leeward telltales tend to stream more or less parallel.

In summary, to sail properly upwind on a catamaran, you should:

• Head up until the windward telltale begins to rise;
• Be careful not to let the jib luff. You must feel the boat: just before the jib luffs, the boat slows down. At that moment, ease the mainsheet slightly and bear away just enough to regain speed while maintaining course;
• Note: if the telltales are perfectly parallel, you are likely on a beam reach with an apparent wind angle of about 45 degrees.

Reaching

On a reach, sailing becomes exciting and highly dynamic.

A catamaran sailing at 135 degrees to the wind in 15–18 knots is like roast chicken with fries — simply perfect.

Here’s what happens:

You settle onto a broad reach. The mainsail traveler and jib traveler are fully eased. The boat begins to accelerate. Observing the telltales — three on the mainsail and two on the jib — you’ll notice that:

The lower telltales generally indicate traveler adjustment, while the upper one reflects sheet tension.

You see the lower windward telltale lifting, so you trim in the traveler. Then the upper telltale rises — so you sheet in. Then it lifts again — and you trim the traveler further.

The result? In 12–14 knots of wind or more, you’ll end up with a mainsail trimmed almost like you would on a close reach.

At this point, the apparent wind will be coming from roughly 50 degrees, and the telltales will stream parallel.

So what’s the difference?

Is it as if we were sailing upwind?

What actually changes?

The boat trim? The crew’s position?

This is precisely why it’s essential to know — without hesitation — which point of sail you are actually on.