Sailing to Jib Telltales
Now let's see how these work for sail trim. The principle is quite simple. Under optimum trim the windward telltales should be jumping about nervously, while the ones to leeward should be streaming aft. If the leeward telltales are jumping or streaming forward you need to ease the sail or head closer to the wind. If the windward telltales are standing straight up or heading forward you have to tighten your sheet or head away from the wind until they go back to their nervous condition.
Not all the telltales in each row will break at the same time. By experience you'll find a forward one which breaks earliest to use as an early warning and one somewhere towards the middle which will be the best overall indicator.
Ideally, all the rows, top to bottom, will show the same action. If not, the jib sheet lead needs to be adjusted forward or aft. The upper rows are the best indicator for lead. If they stall on the leeward side ahead of the bottom rows it means you need more twist in the sail. Move your lead block aft allowing the jib top to twist off, until the upper telltales show the same flow as the lowers. On the other hand, if the windward telltales at the top are stalled (blowing up or forward), move the lead block towards the bow to reduce twist.
After a little practice you'll find one indicator you use 90-percent of the time. It will probably be in the second or third row up, about half way back in the row. Once this telltale is identified consider having a window sewn into the sail so you can easily see its leeward mate.
A second consideration is which is the best telltale to view from the cockpit or under the dodger. After awhile you will find a position which gives you a generally good (albeit not perfect) indicator down lower. If the pointy end is wet, this lower telltale will get a lot of use.
Here is a drawing of using telltales. The top view has the windward telltale streaming aft and the leeward telltale nervous orjumping forward. This indicates the sail is over-trimmed and the sheet needs to be eased.
The second drawing has both sides streaming aft—just about right.
A touch of easing the sheet so the windward telltale was nervous, as in the third drawing, would be a little faster.
In the fourth drawing the windward telltale is reallyjumping, even blowing forward. This shows the sail needs to be trimmed in until the telltale becomes nervous again.
Here is a drawing of using telltales. The top view has the windward telltale streaming aft and the leeward telltale nervous orjumping forward. This indicates the sail is over-trimmed and the sheet needs to be eased.
The second drawing has both sides streaming aft—just about right.
A touch of easing the sheet so the windward telltale was nervous, as in the third drawing, would be a little faster.
In the fourth drawing the windward telltale is reallyjumping, even blowing forward. This shows the sail needs to be trimmed in until the telltale becomes nervous again.
If thejib sheet lead is in the correct fore and aft position, and the sheet is correctly trimmed, all of the luff telltales will be streaming the same way. However, if the lead needs to be adjusted the telltales will show different indications. In the upper left-hand sketch the upper leeward telltale is streaming forward, while the middle and lower are streaming aft. This indicates the top is stalled. To correct this situation ease the traveler car aft, freeing the leech, which allows more twist.
General rules for jib trim:
As the sheet is eased (sailing further off the wind) the lead goes forward.
When the sheet is trimmed (sailing closer to the wind) the lead moves aft.
□ In light airs the sheet is more aft. In moderate breezes move the lead forward. As the boat becomes overpowered, ease the lead aft to twist off the head of the sail.
Lower right, the leeward telltale is streaming aft and the windward telltale is forward. This indicates the leech needs to be tightened by moving the jib lead forward.
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