A sailboat’s rig is a dynamic thing, even though it appears to be fixed in place with stays, shrouds, turnbuckles and so forth. Wire stretches, decks shift, sails change shape and halyards stretch. To make sure your rig is safely set up and well tuned for the best possible performance, it is important to tune the rig every six months or even more often if you are racing actively.
First you need to set up the mast so it is straight from side to side. Use the cap shrouds to adjust the sideways position and measure this with the main halyard; attach a measuring tape to the halyard and measure to the base of the two cap shrouds. Once straight, tighten the intermediates and lowers, while sighting up the mast to make sure it remains straight.
For a standard mast, you can build in a little pre-bend in the mast to maintain good mainsail shape and to keep the spar under constant compression. Tighten the forward lowers slightly so the middle of the mast is secure; then, tighten the back stay and headstay so you have a nice, even curve in the mast with the top or truck no more than six inches or so aft of the hounds. If you have a hydraulic backstay, this is the shape you want when the backstay is fully cranked down.
All boat designs are different; some have natural lee helm, some have neutral helm and some have weather helm. You can tune out lee and weather helm by either raking the mast aft a bit (correct for lee helm) or raking it slight forward (for weather helm). Ideally, when the mast is set up correctly and tuned precisely, and when the sails are trimmed to their best shape for sailing up wind, you want about two degrees of weather helm so you can “feel” the boat.
Thank you for the information. I have heard that tuning the rigging is necessary but had no clear idea of how to do it. Thanks again.
Hello Joe, fancy meeting you here! I hope all is well.
Good information. Will appreciate hearing your advice on shroud tension tuners; i.e. there are several on the market that measure the actual tension of each of the shrouds whether they be solid rod, wire, etc. Which measuring device is the best recommended, etc. Thank you.
Here is one method I use to center the mast.
Using a halyard that is ( preferably )in the center of the mast, take a weighted bag and attach it to the halyard shackle. I have a 30lb bag I use. For J105′s for instance, I use the spinnaker halyard.
Lower the bag over the side of the toe rail where the halyard is against the gunwhale. Then take some tape and mark the height of the toe rail. Let the halyard stretch out for a minute or two.
Then move the halyard around the bow with the weight dangling to the opposite side of the boat, and at same the point let the halyard dangle again and compare to see if the tape is at the same height to the gunwale/toe rail.
Then make adjustments to the vertical shroud until the tape is even on both sides of the boat.
Be patient in the process and you will have a perfectly centered mast.