Ullman Sails Series Part I: Mainsail Controls

us_logo_blue_web_media_rgb_low_resDoesn’t every sailor want to know more about Mainsail controls? We do! The Ullman Sails website is always a place of vast and great knowledge for and rigging. We loved this article on their site and with so many great tips in this post we asked if we could share a snippet of it with you.

Read the full article on their website:  “MAINSAIL TRIM: Make the Most of your Mainsail Controls




The mainsheet and traveler are the two main controls that help you trim the mainsail upwind to maximum efficiency.  It is very important to keep the boom on the centerline of the boat and to keep the top batten parallel to the boom.  Check to see if the leech telltale on the top batten is flowing.  If it’s not, you need to twist the sail off more by easing the mainsheet and pulling the traveler further to windward.

One thing to remember is that more leech tension closes the leech, thus allowing the boat to point higher.  However, if you trim past the point of stall – where the top telltale stops flying – the boat will start to slow down.  Therefore, keep an eye on that top telltale to make sure you are not overtrimmed.

As the boat begins to be overpowered, the traveler should be eased down to reduce weather helm and keep the boat at less than 25 degrees of heel.  As the traveler is eased, you will develop backwind.  This is not a problem.  In puffy wind, the traveler should be played aggressively.  Choppy water usually requires a little more twist in the leech than flat water, so you should pull the traveler higher and ease the sheet.

While upwind in underpowered conditions, the outhaul should be adjusted to keep the sail’s foot shelf half-open.  When all crew members are on the weather rail, the shelf should be closed.  If you have to ease the traveler down frequently in the puffs, you should put in a flattening reef (if possible).  The flattener is a ring in the leech just above the clew. It is independent of the cunningham and will help remove a great deal of fullness from the bottom quarter of the sail.  Initially, do not fully tension the reef, but rather increase the tension as more flattening is required.  Off the wind, both the outhaul and the flattener should be eased to fully open the foot shelf.


Look forward to Next week’s post on Cunningham & Halyard.

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