I have small keelboat (22 feet) that's fitted with running backstays, plus the normal backstay. What is the correct way to use these running backstays? And don't the two types of backstays contradict each other?
Dan Dickison responds:
Thanks for your question. Running backstays may look and seem complicated but they're really not, particularly on a boat the size of yours. The concept behind these stays is that they allow you to control the upper portion of your mast, and therefore adjust the shape of that same area of the sail plan.
Now using them properly depends upon a few things. I'm assuming that your boat is a fractional rig and therefore the designer added the running backs to help support the uppermost portion of the sailplan. In lighter winds, you may not need to use them at all. We used to have a set of running backs on an E-Scow that I sailed on, and we rarely used them in under 10 knots of wind.
When the breeze comes on, so do the running backs. You'll need to spend some time experimenting with their use so that you know just how much adjustment you need given different wind conditions. What I recommend is that you pick an afternoon (preferrably one with moderate winds, say 12 to 15 knots) and head out sailing with your normal crew. Once you've got the sails trimmed in and you're heading upwind, tension the running backstay on the weather side (with the leeward one loose) and then stand at the base of the mast and site up the spar to see what additional adjustment does to the mast and consequently the shape of the sails.
Depending upon where the stays are fitted to the mast, tensioning them may also affect the tension of the headstay, so it's also important that you look at your headsail after you adjust the running backstays. These kinds of observations are the best way to learn about the use of the running backstays on your particular boat. Also, if your boat is fitted with a speed gauge, you can correlate that information as well to better understand the outcome of the adjustments you make with the backstays.
Now, you ask about the potential of duplication with running backs and what most sailors refer to as the permanent backstay. What's involved here is really geometry. The running backs are usually attached somewhere below the masthead, so the force they exert on the spar is largely different than the force exerted by the permanent backstay, and thus the end result on the shape of the sail plan is slightly different as well. Also, running backstays aren't set in exactly the same plane (getting geometrical here) as the permanent, so they tend to exert a side force on the spar and thus the sail plan. That's another reason why it's critical to site up the mast and observe the changes made by adjusting the running backstay. After you've become more comfortable with the range of adjustment on your running backstays, you won't need to site up the spar. By that time, your eyes will be trained to see the changes in sail shape and that will become your gauge regarding the appropriate tension for the runners.
One final word of caution. The improper use of running backstays has been known to get sailors in trouble. If you're out sailing in big breeze, say over 24 knots, and someone forgets to release the running backstay on a jibe, or worse yet, put tension on the new weatherside one, you could end up breaking the mast. So give yourself some time to learn these stays and their general use when the wind is moderate and you should be good to go.