PS Advisor April 2011 Issue

PS Advisor: Pondering the Keel-ectomy

Will chopping 14 inches off the keel kill performance?


A lead-ballast wing keel awaits fitting at the Catalina factory in Largo, Fla.

My wife and I have moved our O’Day 39 to the Oriental area of North Carolina. We have the three-cabin version without the formal nav station. Our draft with our lead-ballast keel is 6-feet, 4-inches. Since we are going to be sailing in the Pamlico Sound, Neuse River, and the Intracoastal Waterway, we are being told we should modify our keel to better cope with the shallower water.

I was going to reduce the keel by 14 inches and put a wing on it. Some of the area sailors and yards are suggesting I go with a bulb instead. What would be your take on this modification? I really like the way my hull handled the waters on the West Coast and the Channel Islands area where we bought and sailed our boat before bringing it to North Carolina. Can I still get the same performance with the right modification?

Ron and Lucy Seegan
Cool Change Too, O’Day 39
Oriental, N.C.

Anyone considering a keel-ectomy should first consider the original design, and how well it is suited for such a modification. The O’Day 39 began its life as the Jeanneau Sun Fizz. It was drawn by Frenchman Phillip Briand, whose well-known design firm has produced a number of recent Jeanneaus, as well as some monumental custom yachts such as the 220-foot Vertigo launched in February by Alloy Yachts of New Zealand. (Vertigo, by the way, has a shoal draft of 15 feet.) As part of an agreement with Jeanneau, the now defunct O’Day Corp. began building the Sun Fizz hull and selling it as the O’Day 39 in 1981. After about 120 hulls, C. Ray Hunt and Associates re-designed the cabinhouse and interior, and it was renamed the O’Day 40.

The O’Day also came in shoal-draft with a 4-foot, 11-inch keel. This version would give you a decent benchmark for performance under sail. The boat we sailed for our test in the 1990s had a shoal-draft keel. The reviewers pointed out that the long keel was “much to be preferred,” which should give you an idea of the kind of sacrifice you can expect. For comparison sake, the New England PHRF gives the long-keel O’Day 39 a 6-second per mile edge over the shoal-draft keel.

The bottom line is that neither a bulb or a wing keel will deliver the same performance as the original. Chopping off that much keel at the leading edge, where the lift is generated, is sure to diminish your O’Day’s ability to point.

Stability is also a concern. Both bulb and wings help keep the boat’s center of gravity low, but you will need to add lead to retain the righting moment that the deeper keel offers.

If it is carried out right, the wing keel should give you a better performance on the wind. Both keels can also introduce other problems when anchoring in current (rode rap) or grounding (bulb or wing wedging into rocks). However, depending which branches of the Neuse River you plan to explore, you might not have much choice.

If you plan more offshore cruising, we would leave the keel as is and see if you can live with it. If, however, your future home lies up a shallow creek, you could consult a yacht designer and keel manufacturer (try Mars Metal, s) about your options and what it would cost to convert to shoal draft.


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