The Complete Rigger's Apprentice: Tools and Techniques for Modern and Traditional Rigging, Second Edition

Mainmasts are more than just great big mizzens. The loads they bear are of a whole other order of intensity and complexity. Loading from staysails is particularly significant; unlike mizzen staysails, the ones on the main are meant to be trimmed in hard when the boat goes to weather, and this adds tremendously to the compression load on the mast. With more at stake in terms of load, designers can go even further afield in search of workable rigs, and work even harder to make those rigs interact with the hull. 

Troubador Veteran yacht designer Ted Brewer is a direct heir to the people who developed rig scantling formulas. But his designs, for everything from gaff-rigged schooners to BOC racers, have always been characterized as much by freshness and adaptability as by classical conservatism. So when client Dr. Paul Bubak asked for a very easily handled but very efficient fractional rig, Brewer came up with the artful sail plan shown in Figure 8-8. Traditionally, cruising rigs have minimized the effort expended on staysails by breaking up the single large one of a sloop into two or three smaller ones, to make a cutter. But another method is to shift staysail area into the less truculent mainsail.

This results in such a small staysail area that you no longer need to run the jibstay all the way to the masthead in order to have room for the sail. A "fractional rig" results, so named because the stay only comes three-fourths or seven-eights or fifteen-six-teenths of the way up the mast.

Less staysail-wrestling also means less jibstay tension, and thus less mast compression, so fractional rigs can have slightly lighter masts for the same total sail area.

It's not all plusses, however. You might not have the chore of changing headsails, but you do have to reef the main sooner and more often. And savings in headsail costs are offset by increased mainsail costs, particularly if it has full battens, lazyjacks, and other options to make the sail more efficient and easier to handle.

Troubador's rig has a very small (non-overlapping) jib and a very large, very tall main. It's a bit radical-looking for a cruising boat but Brewer simultaneously pushed the envelope and kept his scantlings conservative. The result is a safe rig and low work load for Bubak and crew, without correspondingly low performance.

Rig Details With so little sail area above the jib-stay, the masthead needs little lateral staying. Diagonal jumpers are sufficient, and they also act to brace the mast against the forward pull of the jibstay. Running backstays act as backups for the jumpers for fore-and-aft pull; they can be set up in high winds or choppy water or when the mast is heavily bent by the backstay. Many fractionally rigged race boats dispense with the jumpers and rely solely on running backs. This saves weight and windage but means the runners must be set up promptly with each tack or risk losing the stick. Combining jumpers, runners, and a conservative mast section makes for low labor (you only need the runners about 20 percent of the time) and high safety, and they're still light enough not to cut too much into the performance.

A final detail is that Troubador also has a forestay, something rare in a fractional rig. It helps brace this high aspect Mast, leaves enough space for a good-sized working staysail, and is a good wire to to the hang a storm staysail on-low and well aft. In light airs this stay can be disconnected and made off aft and to one side, for easy tacking of a big jib.