What they’re made of; their positions in modern sailboats
The Anglo-Saxon word mæst refers to a tree trunk, and for many centuries that’s exactly what sailboat masts were. Nowadays, most masts are made of metal: aluminum on small boats and steel on large ships. Some gaff-rigged sailboats still have solid, stumpy wooden masts, and many older Bermuda-rigged cruiser-racers have tall, hollow wooden masts, glued together in two long pieces.
 |
| A conventional thin-walled aluminum mast(bottom) with one or two spreaders requires a section of large diameter. Making the wall a little thicker (top) and incorporating multiple sets of spreaders makes a smaller section possible. The result is a lighter, bendier, harder-to-tune spar that allows better airflow over the mainsail of a racing sailboat. |
Aluminum alloys—especially #6061-T6—have proven successful on pleasure boats, requiring a minimum of maintenance and being comparatively light and long-lived. For these reasons, aluminum largely replaced wood in the masts of boats built after 1960. However, an aluminum mast does require adequate staying because if it bends excessively under compression, it’s likely to fold and collapse—unlike a wooden mast, which can take a lot of punishment and spring back unharmed.In the 1990s, carbon fiber became increasingly popular for masts, to the point that it is now the material of choice for new large yacht masts. Carbon fiber is light, tremendously strong, and more supple even than wood. It is also expensive, more difficult to ground, and can set up galvanic corrosion with metal fittings. For these reasons, many sailors still prefer aluminum.Thick-sectioned carbon-fiber masts are used without stays in large cat-rigged cruisers, whereas racing yachts use highly stayed, thin-sectioned carbon masts. Strong as it is, a carbon-fiber mast can still break. The 128-foot carbon-fiber mast of the 110-foot catamaran
Kingfisher II broke suddenly in two places in a 25-knot breeze following several days of storm-sailing in the Southern Ocean in February 2003. The dismasting ended
Kingfisher II’s at-tempt in the Jules Verne Challenge around-the-world speed record, which then stood at 64 days.Pleasure boats mostly have one or two masts, although a large schooner may have three. Following are their relative positions in a boat, according to individual rigs:
- sloop: one quarter of the waterline length abaft the stem
- cutter: one third to one half the waterline length abaft the stem
- yawl: mainmast about one quarter of the waterline aft of the stem; mizzenmast on (or close to) the after end of the waterline
- ketch: mainmast about one third of the waterline aft of the stem; mizzenmast about one sixth of the waterline length forward of the after end of the waterline
- schooner: foremast about 20 to 25 percent of overall length abaft the stem; mainmast 52 to 60 percent of overall length abaft the stem
Multiple masts should not be set up exactly parallel to each other because they then appear to be closer together at the masthead than at deck level. This applies particularly to schooners. To compensate for this illusion, each mast must rake aft a few degrees more than the one ahead of it.See also
Galvanic Corrosion; Sailboat Rigs; Wooden Spars.
