Design and Construction
Kirby drew the San Juan 24 to the IOR Quarter Ton Rule, and the hull reflects that racing pedigree. She is a recreational keelboat built predominantly of fiberglass with wood trim, carrying a raked stem and a raised reverse transom. The fixed fin keel and internally mounted spade-type rudder controlled by a tiller give her the underbody of a thoroughbred racer rather than a cruiser. At 24 feet overall with an 8-foot beam and a displacement around 3,200 pounds backed by 1,650 pounds of lead ballast, the design sits at a ballast-to-displacement ratio near 52 percent, a figure that explains much of her reputation. Owners report she is fast and weatherly going upwind, and her PHRF racing average handicap of 219 — with a recorded high of 231 and low of 216 — places her firmly among quick quarter-tonners.
Rig and Handling
The masthead sloop rig drives a sail plan that rewards clean trim. The boat's narrow underbody aft, however, is reported by owners as the possible cause of her behavior dead downwind in heavy air under spinnaker, where she can be a little squirrelly. That same hull shape is what makes her so effective on the wind, so the trade is inherent to the design. The tiller and spade rudder give precise command in close quarters, and the trailerable nature of the boat means she can be launched and tuned without a permanent slip.
Accommodations
For a 24-foot racer the interior is surprisingly social. The design provides sleeping accommodation for five people, a count that speaks to Kirby's ability to package berths inside an IOR racing shell without destroying the lines. The wood trim noted in the construction record softens an otherwise fiberglass interior and ties the boat to its early-1970s American building tradition.
Known Issues
The one handling caveat that recurs in owner reports is the downwind squirrliness under spinnaker in heavy air, possibly a result of the narrow underbody aft. This is not a structural defect but a dynamic characteristic: the stern does not have the beam to settle the boat when broad-reaching at speed, and a helmsman caught unaware can find the boat twitchy. It is a manageable trait with practiced spinnaker technique rather than a fault requiring repair.
The Verdict
The San Juan 24 is a purist's quarter-tonner: a Kirby-designed, IOR-rule racer that sold 1,200 copies and earned its "most popular quarter tonner ever" tag through sheer sailing ability. She is quick upwind, tidy to trailer, and berths five in a package under 30 feet. The only behavioral quirk is a downwind skittishness in heavy air that comes from the same narrow stern that makes her weatherly.
Pros
- Fast and weatherly going upwind per owner reports
- IOR Quarter Ton class racer pedigree from Bruce Kirby
- 1,200 built; most popular quarter tonner ever by owner account
- Trailerable with sleeping for five
Cons
- Dead downwind in heavy air under spinnaker can be a little squirrelly
- Narrow underbody aft contributes to downwind twitchiness
