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Old 04-30-2002
Dan Dickison Dan Dickison is offline
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Speed differential

I sail on a Dehler 37cws. Recently we were racing in 25 knots of wind with one reef in the main and the No.3 jib and while we were beating upwind, we had much less boat speed on port tack than on starboard tack. The difference was roughly one to one-and-a-half knots. Do you think we have a problem with our rigging?

Dan Dickison responds:
Thanks for your question. I think you've put your finger on the problem right away. Assuming that everything under the water is symmetrical (keel and rudder and hull), the problem most likely resides either in your rig tune, your sail trim, or your weight placement. My bet is on the rig tune.

Before you start messing with the rig, ask yourself these questions first: is the boat listing at the dock when at rest? Meaning is the fuel tank or water tank or other stowage causing an inherent imbalance on board. If that's not the case, are you trimming your sails the same way from tack to tack? Check that the jib leads are in the same position on each tack and that all of the other settings are uniform on each tack. Is your crew weight placed identically from tack to tack?

Once you've answered those questions and ruled out those areas as probable causes for your problem, it's time to get out the wrenches because you're down to rig tune. Before you leave the dock or your mooring, site up your mast track to make sure that the mast is in column. You can also use the main halyard as a reference to determine where the masthead is from side to side, or better yet use a long, flexible tape measure to get a more precise idea of just where your masthead sits relative to the center of the boat. Also, make sure that the mast is in column and that the rig is tuned so that the mast looks the same from side to side when the sails are set and drawing. If you do all of these things, your boat speed differential from tack to tack should disappear.

You might also want to take a look at the rig-tuning primer we wrote as a sidebar for this article by Dobbs Davis: Rig Tune Innovations on the 1D 35. Here's wishing you the best of luck in resolving your problem.