Setting Your Jib Tension and Mast Rake

     As the Club 420 Midwinters kick off tomorrow in Jensen Beach, FL, some of the country’s best youth sailors will set up on their boats on the lawn and make decisions about setting their mast rake and jib tension.  These settings are essential for overall speed and pointing abilities, and are often overlooked by mid- fleet and back of the pack sailors who either do not fully understand the effects of each setting, or simply do not put forth the effort into getting these settings in the right place.

     Further complicating the jib tension setting is the effect of the mainsheet.  Trimming hard on the mainsheet bends the upper part of the mast, tightening the jib’s luff curve, and flattening out the sail.  Thus, in lighter air and thicker chop, when you are often easing the mainsheet to power up, a looser jib tension is necessary to give some depth and power to the front of the jib.  Many sailors simply pull the jib halyard on as hard as possible and leave it there for the day.  These sailors will experience a combination of lethargy and hobby horsing from their boats as they ease to go through a patch of waves or a lull in the breeze.

     In windy conditions where the boat is raked back and is overpowered, the top skippers are easing the mainsheet often to keep the boat flat, and keep their crews on the wire.  This is particularly effective in a Club 420, as the jib leads are set far to the side, giving the boat a naturally wide slot (the space between the jib and the main) compared to a boat like an FJ.  The issue that many sailors run into in breeze is not having enough jib tension.  As you crack off the main when entering a puff, the mainsail depowers.  However, easing the main takes the bend out of the top of the mast, loosening the jib’s luff curve and powering up the jib.  This prevents you from fully depowering and going your fastest in the big puffs where the best heavy air sailors are making the biggest gains.  So, make sure to tighten your jib tension when you are forced to ease the main consistently to stay flat upwind.  Furthermore, you can also go tighter than normal with your jib tension in flatter water, where you don’t ease off very often to go through lulls or chop.

     Whether it is a 420, FJ, or any other boat that has jib tension and mast rake settings, the top sailors all invest their time and effort into measuring, marking, and knowing exactly what these settings are before races start, and will continue to adjust them on the water as the wind changes throughout the day.  If you want a place in this elite group, you will need to put the effort in too!

Here are a few helpful tips and tricks for setting up your jib tension and mast rake:

1. C 420 Tuning Guide – Jib Tension and Mast Rake: http://bit.ly/TuningGuide

2. When you are on the water, trim your main into where you would normally when sailing upwind.  The leeward side stay should just start to go slack if you pull an inch harder.  Adjust your jib tension accordingly.

3. Install quick pins in your side stay adjusters for easy on the water adjustments to your mast rake.  Use a sail tie to tie the pins to the bracket so you won’t ever lose one in the water.

4. Make marks up and down the side of your mast to measure your rake and jib tension with the jib halyard.  Remember, your jib tension has a large effect on your mast rake and vice versa.  You should typically have four settings four your general mast rake setting, and two or three jib tension settings for each general rake setting.  Use different colored markers on both the mast and pin holes to distinguish the marks on your mast for each rake and jib setting.  You don’t want to get confused when making changes on the water.

Example: Wind Speed (Waves)/ Rake Setting (Jib Tension)
Light (Flat, Choppy, Wavy) – Mark in Red
Medium (Flat, Choppy, Wavy) – Mark in Blue
Heavy (Flat, Choppy, Wavy) – Mark in Black
Honking (Flat, Choppy, Wavy) – Mark in Green

5. Once your tension is set, grab the side stays and rotate them in an upright circular motion.  The circles will be larger or smaller depending on how tight or loose the tension is.  This is a great way to measure your jib tension if you do not have exact measurement tools.

See you on the water,

Zim Coach