Sailboat Racing Trim — Part 12

In Chapter 12 of his book Racing Trim, Bill Gladstone talks about asymmetric spinnaker trim. The following post shows a short summary of what I learned from that chapter.

The main controls for an asymmetric spinnaker are:

  • Sheet — The sheet is most used and gives the most immediate feedback about sail trim.  Use it to keep a curl in the sail.
  • Halyard — The halyard can be eased on a broad reach to let the spinnaker rotate further to weather.
  • Tack line — The tack line should be snug to the tip of the pole on a close reach.  It can be eased on a broad reach to make the sail act more like a gennaker.  It also lets the sail rotate out from behind the main.


Don’t go dead downwind with an asymmetric spinnaker.  Instead, reach up and sail fast.  The extra speed of reaching up more than compensates for the extra distance of sailing off the rhumb line.  The driver and trimmer must coordinate.  Drive up and load will build in the sheet.  Bear off and ease spinnaker sheet and turn down a bit.  Keep this pattern going to maximize speed and get the benefit of the extra power from the puffs.


Ease the sheet to let the kite curl.  It will fill a bit; and then ease again.  Keep this pattern going.  You may want to ease the halyard on a broad reach to let the sail rotate further out to weather (but if the sail hangs down instead of rotating, it is eased too far).  If the sail stalls, it may be because it’s over trimmed.


If there’s about 15 knots of wind, it may be possible to plane.  When done right, it will be worth it to reach up and plane down.  However, be careful — if you can’t plane, you will lose speed from the extra boat maneuvers.  Make sure the effort is resulting in extra speed overall.


Be really careful ducking boats while going downwind.  It could result in extra acceleration that leads to rounding up or broaching as you pass the stern of the boat you are ducking.  Also be careful of your pole as you progress around the race course.  It could be easy to clip another boat by misjudging where the pole extends to.  A lot of classes do not allow the sprit to be extended before rounding the mark.


This is the twelfth in a series of posts based on Bill Gladstone’s book Racing TRIM from the North U. Series.  Periodically, I post about a chapter or two.  This will be my short summary of what I’ve read.  You can read the posts to get my abbreviated summary; or you could read through the books with me.  Your comments can help point out what you find most interesting, or even poke fun at what I do and don’t know.  If you are interested in getting this book, you can find it in the online store section of for $25.