Jib Telltales and Lead Block Position

Jib Telltales and Jib Lead Blocks on a Roller Furling Jib

Several of my sailing friends have roller furling jib sails.  This makes for a convenient set up to set and then later douse the jib.  Pull a sheet and the jib sail sets.  Pull the furling line and the jib rolls up neatly around the forestay.  What could be better???

To make sure that the jib is properly set, a set of three or four telltales (yarn or nylon) attached near the jib sail’s luff helps show whether the jib is set properly when close hauled or on a close reach.  The telltales are typically installed about half way up the luff and also at one quarter and three quarters of the way up the luff.  The telltales are attached about six inches aft of the luff (forward edge).  One telltale is set on each side of the sail at all three positions.  This system makes for both windward and leeward telltales at each position.

To make sure that there is approximately equal tension on both the foot and leach of the jib, simply allow the boat to swing slowly toward the eye of the wind and observe the telltales.  They should all “break” (flutter) simultaneously as the sail’s angle of attack approaches zero degrees.  The placement of the jib sheet lead block will control when and how the telltales “break”.  If the top telltale “breaks” before the lower ones, there is too much downward tension on the jib sail leach.  The jib sheet lead block is too far forward and needs to be moved aft.  If the lowest telltale breaks first, there is too much tension along the jib sail’s foot.  The lead block is too far aft and needs to be moved forward.

Again, what you want is for all of the telltales to break together - - indicating that the jib sheet has about equal tension on both the foot and the leach of the jib.  When the jib sheet lead block is in the correct position, the skipper can sail along close hauled or on a close reach and observe the telltales; both the windward and the leeward telltales should all be streaming in the wind.  If the windward side telltales are not streaming, the boat is pinching and the skipper should fall off until the windward telltales again are streaming.  If the leeward telltales are not streaming the jib sail is stalled…  The skipper needs to head up a bit; or the jib sheet should be eased out till the telltales are streaming.

A problem that sailors with jib roller furling gear have is that as the jib is furled (rolled up partially) to decrease the jib’s size in stronger breezes, the telltales get rolled up are no longer visible. 

 

If the telltales are no longer visible, the skipper cannot easily determine if the jib sheet lead blocks are still in the right place.  There is a good chance that the lead blocks need to be moved forward as the jib sail is partially furled.  How much forward is the problem.

 

If the wind pipes up more, the skipper will often roller furl the jib even more.  Again, does the jib sheet lead block need to be move again?  How far?

 

Having multiple sets of telltales on the jib is the answer.  As the jib is rolled up, there are always telltales visible to the skipper - - at least until the sail does not have good enough shape to drive the boat.  With these extra telltales, the skipper can now have a visual reference for proper placement of the lead blocks.

 

If the jib sheet lead block needs to be moved forward as the jib is roller furled, it is a good idea to have marks on the track, toe rail, or cabin top to show the correct lead block placement.  Remember to move the lead block for both jib sheets to the same respective position.  And, as the breeze decreases in strength, and the jib is unfurled, remember to move the lead blocks aft to their proper place.

Remember that if the lead block is left in its original position as the jib is furled, there will be excessive tension on the foot of the jib sail.  This tension on the foot will allow the jib to twist off in the upper third of the sail - - spilling wind and not driving the boat.