Ask A Coach – How To USE Those Sail Shape Controls

December 18, 2008

This past weekend I gave a day long lecture on the fundamentals of sail trim and balance for JWorld Annapolis, the best damn sailing school in America. This is approximately six hours of discussing the two modes of sailing, the three sources of sail power, the controls that shape our sails, what do we want and when do we want it.

As with all my courses, lectures, clinics and events I make a pledge to be “tech support” to anyone who participates. It is never too early or too late or too weekend to call or write with a questions. One of the participants quickly sent this one in:

“Thanks Kristen, I enjoyed the course.
I did have a question. As we talked about the adjustment of controls I
wondered what the increment of the adjustment should be? At one point in
the class it was mentioned that the halyard might be adjusted by 1/2
inch or so to adjust the draft position. Is it generally true that
adjustments in controls such as halyard, cunningham, and outhaul are
made in fractions of inches?

-Doug”

This is a pretty common question, and one that confounds many newer sailors. Sail controls are often approached as though they only have two settings – on and off. But in fact the power of sail controls (halyards, sheets, outhaul, backstay, cunningham, traveler, vang, car position, etc.), and the challenge of sailing, is in their broad range and nearly infinite position possibilities.

The short answer is YES. Small adjustments in controls can have major impact on the shape of the sails – and there is the key. It is the shape of the sail that you should be concerned with rather than the number of inches of adjustment.

Let’s take the halyard for instance. Halyards are often pulled as tight as the person can pull or until the halyard groans and then forgotten about. On a roller furling jib or genoa they may be forgotten about for the whole season!

But the halyard is a major control for the amount of draft and draft location in sails and draft is one of only three sources of power it cannot be ignored. If you go down to your boat and play adjust the halyard through a range of three inches you will see the difference between being the right setting and too tight or too loose really can be in the range of less than an inch. Over-tension the halyard will pull the draft too far forward and over-flatten the sail making it less powerful in light air or in chop. Under-tension and you’ll create a sail that is too deep and eliminate any draft control your Cunningham could impart.

I say in my lectures that “there are NO set it and forget it controls.” As wind velocity and sea state change so must halyard tension. You’ll need more halyard tension as wind velocity increases to help depower your sails and keep the point of maximum draft in the designed location or even more forward. The adjustment to get the sails “just right” is VERY small.

All of the controls have range and none of them should be considered on or off. Play the ranges and keep experimenting. You’ll find, over time, that the range of adjustment will get smaller in overall range but more “delicate” in how you play it.

It is worth mentioning that controls that are easy to adjust get adjusted often. Every control on the boat should have enough purchase and be in good working order so that it can be adjusted by anyone and can be adjusted through the whole range. So it may be neccesary to increase the purchase or update to newer hardware to get the most out of your controls. If you are in a one-design racing boat make sure you check your class rules to make sure there aren’t rules limiting what you can add.

I have included below three PDF files that may be helpful. The first is a basic matrix that shows which sail controls impact which power source. The second and third are what I would consider BASELINE set-ups for mainsails and jibs/genoas. These are rough starting points that can be applied to most keelboats. Each boat has quirks, the design and distribution between the main and foresail are important considerations for fine tuning these charts. If you’d like to develop a similar matrix for your boat call me and we can discuss it.

Additionally, tell me what you think of the way they are posted/distributed. This is a new service I am trying for posting PDF’s and other media. Hope it is helpful.

Fundamental Sail Control Matrix

Get your own – Open publication