We have previously discussed both form stability and ballast stability as concepts, and these certainly are useful when thinking about sailboat design in the abstract. They are less useful, however, when you are trying to evaluate individual boats that you might be interested in actually buying. Certainly you can look at any given boat, ponder its shape, beam, draft, and ballast, and make an intuitive guess as to how stable it is, but what's really wanted is a simple reductive factor--similar to the displacement/length ratio, sail-area/displacement ratio, or Brewer comfort ratio--that allows you to effectively compare one boat to another.

MY LAST POST about that abandoned Swan 48 floating around south of Bermuda has created some buzz it seems and numerous people are now making noises about retrieving it. To help inform and inspire would-be salvagers, I thought I should share some of what I know about these boats. I've sailed them back and forth between New England and Caribbean several times and have also raced a bit on them—around the cans and in one Bermuda Race.

You know, of course, that Nautor Swan of Finland, founded originally by Pekka Koskenkyla, has an excellent reputation. They've been building high-end production fiberglass sailboats for over 40 years, most of them what I'd call cruiser-racers. Most older Swans have sleek, modern hull forms, according to the era in which they were built, but they are also a bit heavy, as they are very solidly constructed with teak decks and lots of heavy solid-teak interior joinery.

I spent a day hanging out with multihull designer Chris White a while back and came away all buzzed up over his latest idea. The basic concept, as you can see in the image from his website up top, is pretty simple: two jibs and no mainsail. What isn't immediately clear from the photo is that those aren't conventional pivoting wing masts behind the sails. The masts in fact rotate through a full 360 degrees and have controllable flaps on their trailing edges, so that they too can act as sails and create lift at any wind angle.

At the end of our last discussion on stability we mentioned the old mono v. multihull worst-case-scenario debate re sinking to the bottom (monohull) versus capsizing on the surface (multihull). This time we'll focus on that which drags the poor monohull to the bottom, which is, of course, its ballast. Ballast, ironically, is added to a boat to help it stay upright. As with form stability, the principle is obvious: an object is harder to up-end if a heavy weight is placed at the bottom of it. Witness the iconic inflatable punching clown. With the majority of its weight concentrated at floor level, the clown pops back upright every time you knock it down. This, of course, is exactly what you want your sailboat to do.

Stability, fundamentally, is what prevents a boat from being turned over and capsized. Whether you are a cruiser or a racer, it is a desirable characteristic. A boat's shape, particularly its transverse hull form, has an enormous impact on how stable it is. This so-called "form stability" is one of the primary reasons you should be interested in the shape of a boat's hull.

The basic principle is self-evident: an object that is wide and flat is harder to overturn than one that is narrow and round. With this in mind, you can usually see at a glance what hull shapes have the greatest form stability. Wide hulls are inherently more stable than narrow ones; given two hulls of equal width, the one with less deadrise and a flatter bottom is more stable than one with more deadrise and a rounder bottom.

I HAVE ALWAYS been very attracted to junk rigs, first, I suppose, because they seem so very strange and archaic. As one early Western proponent, a British cruiser named Brian Platt, who sailed from Hong Kong to California under junk rig in the late 1950s, once wrote: "Nobody could have designed the Chinese Sail, if only for fear of being laughed at. A device so elaborate and clumsy in conception, yet so simple and handy in operation could only have evolved through trial and error."