Settling the Keel-shape Debate

With the Intracoastal Waterway shoaling getting worse each year, its no wonder that we’re seeing a flurry of shallow-water cruisers. Recent debuts include Rod Johnstone’s J/95 (PS, August 2010) and Rodger Martin’s Presto (PS June 2011), both centerboarders. This month, we look at another shoal-draft cruiser, the Island Packet Estero, a 36-footer with a full keel.

Bucking the tide of fin-keel designs that have dominated the market since the late 1970s, Island Packet’s owner, CEO, and chief designer Bob Johnson is an unabashed proponent of a long, full keel for cruising. Granted, Johnson’s U-shaped hulls and foil-shaped keels are a far cry from the traditional wine-glass shapes of the 1950s, but they still have much in common with these older designs.

Much of the debate over the pros and cons of a full-keel design center on performance. Full keel fans argue that full keels generally track better, ride more comfortably, and allow for a shallower draft while avoiding the problems associated with centerboards, ballast bulbs, or wing keels. Fin-keel aficionados will deride full keel’s drag-inducing wetted surface, and point out that the low-aspect underwater foil can’t deliver the lift needed for good windward performance.

As some have concluded, somewhat tongue in cheek, the full keel is superior for going nowhere—either hove to, or aground. Few would argue this. The lateral resistance of the keel helps maintain a constant angle to the wind and sea when hove-to, and grounding loads are widely distributed to the hull structure, reducing the potential for damage. In a sense, a full-keel copes well with worst-case scenarios, and this is not such a bad thing when cruising.

The tracking advantage often touted in full-keel boats is not so cut-and-dry. Full keel proponents contend that when broad reaching in tradewind conditions, a full keel reduces the strain on steering gear and the crew. Critics counter that while high-aspect racing designs are purposely skittish, a well-balanced fin-keel cruising boat will sail true and comfortably—and faster than a full-keel boat in the trades.

Opinions diverge even more sharply when gale-force winds and following seas enter the picture. Critics contend that the directional stability of a full keel, particularly one with a deep forefoot, can make it more difficult to recover from a near-broach, adding work to steering gear and crew. Full-keel proponents counter that full keels better resist broaching (particularly when towing a drogue or warps) and that for shorthanded crews, the ability to lie comfortably hove-to becomes more important than agility on the face of a breaking wave. Both schools have plenty of examples to support their claims.

As for arguments over stability and seaworthiness: Any contention that full keels are inherently more seaworthy than fin keels oversimplifies the subject. (We will be exploring structural strength and ultimate stability in an upcoming issue.) The seaworthiness of fin-keel cruisers is well established, and an ability to tack on 20 miles to windward per day certainly counts for something when trying to avoid bad weather.

At times I think the fin-versus-full keel debate overlooks an important point: The keel is just one of many components that make up a good cruising boat, all of which must work in concert. And when it comes to comparing modern cruising designs, good judgment and seamanship have more to do with seaworthiness than the cut of a jib or the shape of the keel.

 

Read More on These Topics

• Sails, Rigging & Deck Gear