Rig tuning for cruisers
Correct rig tension will maximise the efficiency of your boat’s sails as well as reducing stresses on the mast. David Pugh demonstrates a simple rig set-up
Top tips for safe and efficient sailing
As a cruising sailor, it’s tempting to simply set up your rig at the beginning of the season, then leave well alone. Perhaps you leave the mast up, perhaps you mark the position of the turnbuckles before the mast comes down, perhaps you set the rig up from scratch or perhaps you pay an expert. All these can work, but none are immune from one basic problem: boats move. How much depends on the boat’s construction, particularly whether the mast is keel- or deckstepped, but most will do so within a few days or weeks after the initial rig tension is applied. The boat may continue to do so over time and rigging may stretch, especially when new, so it’s worth knowing how to correct it yourself.
My own boat, Contessa 26 Red Dragon, is a devil for this. During the winter she sits on a trailer with the mast down, the keel supported along its length and in turn supporting the superstructure, aided by six pads and a bow post bearing on the hull. At launch, these forces all change: the buoyancy of the hull now supports the keel, and the mast foot pushes down on the laminated deck beam under the step. The rigging, meanwhile, increases the pressure on the step while trying to pull the chainplates through the deck. I’ve never measured her beam before and after applying rig tension, but I suspect she becomes significantly wider. She certainly doesn’t maintain her initial rig tension.
Benefits of correct rig tension
The first and most fundamental benefit of correct rig tension is safety. An improperly supported mast is put under all sorts of stresses that it is not designed to endure, and dismasting can be the result. Try sighting up the mast when the boat is close-hauled in a good breeze. If the lee shrouds are slack and the middle or top of the mast is sagging to leeward, your mast is not properly supported and you should check your rig tension.
The second benefit is efficiency. The combination of rig, spars and sails is anything but simple, and if your sailmaker has done their job properly and measured your boat rather than making your sails from documented figures, the luff curve of the main and the hollow of the jib or jibs will have been cut to suit the bend in the mast and the forestay tension at the time of measurement. That means you’ll need to be able to replicate that situation when you set up the rig in order to gain maximum efficiency from your sails. And, just to make things harder, as time goes by and your sails stretch, these optimum settings will change.
Conditions also affect the best settings for your rig. Light airs demand softer settings than sailing in a gale, and you’ll often see racers tweaking their rig tensions to suit the conditions. For cruisers seeking to set up and forget about their rig, the best option is to err towards setting up the boat for stronger winds, especially with shroud tension. Forestay tension can be more dynamic, provided your boat has an adjustable backstay.