Sonar Sailboat Buyer's Guide, From Ontario Yachts Hulls to New Rondar Boats

The Sonar sailboat, a keelboat designed by questionnaire

The Sonar sailboat is one of the few designs that started with a survey. Members of the Noroton Yacht Club in Darien, Connecticut, commissioned it, and the class association says scores of sailors from four clubs filled in a questionnaire about what they wanted in a day racer. Their answers ruled out most existing classes. Bruce Kirby, already famous for the Laser, turned the results into a 23 ft keelboat in 1979, and the first boats were built in 1980.

The brief, as Kirby later summarized it for the American Sailboat Hall of Fame, was a boat that was exciting to race, easy to handle for sailors of varying ages and abilities, trailerable, self-bailing and reasonably comfortable. Or, in his words, a boat that could be sailed without breaking your neck. Kirby said he thought it was the best boat he ever designed because it met every criterion. The Sonar was inducted into the Hall of Fame in 2004.

Where Ontario Yachts fits in the Sonar story

Several builders have produced Sonars. The first was Seidelmann Yachts in New Jersey, which went out of business in 1986. Others include C. E. Ryder and Shumway Marine in the United States, Ontario Yachts and DS Yachts in Canada, and a few boats from Carbon Index in the UK. Since 2015 the class builder has been Rondar Raceboats in Wiltshire, England. Wikipedia and sailboatdata both put the total at about 860 boats.

Ontario Yachts is a Hamilton, Ontario, builder that sailboatdata lists as in business since 1961 and led since 1986 by Dirk Kneulman Jr. and Don Oakie. The company survived the boating slump of the mid 1980s partly by taking on non-marine work, including the fiberglass support for the pitcher's mound in Toronto's SkyDome. Ontario-built Sonars still turn up regularly in North American classifieds; the U.S. class recently listed hull 678, a 2002 Ontario boat, for sale in Port Washington, New York.

For a buyer, the builder name matters less than the measurement certificate and condition. Every builder worked from the same class molds and rules, so a well-kept Ontario hull can be fully competitive, though later Rondar boats are noted for coming in under minimum weight with a factory reinforced keel sump.

A sit-in cockpit and a no-hiking rule

The Sonar's defining feature is the cockpit. It is 11 ft 6 in long, has room for eight people and is contoured so that, as the class puts it, your backside is always higher than your feet whether you sit on the seats or the side deck. Crew face into the boat rather than dangling legs over the side, and hiking is not permitted under class rules. That combination is why the boat works for juniors, seniors and disabled sailors in the same fleet.

Controls are simple but effective: internal boom slab reefing, a 4:1 mainsheet, an adjustable backstay and a boom vang. The small cuddy is mainly for stowage and a portable head, though it can be fitted with two berths. There is no inboard engine; Sonars are towed, sailed off moorings or launched from trailers.

Light, stiff and able to plane

The Sonar displaces 2,100 lb with 930 lb of lead in the fin, a ballast ratio of about 44 percent according to sailboatdata. The class lists 250 sq ft of main and jib and a 245 sq ft spinnaker on a 23 ft hull with a 19 ft 11 in waterline and 7 ft 10 in beam. Sailboatdata calculates a sail area to displacement ratio near 26 and a displacement to length ratio around 119, which explains why the boat can plane downwind in a breeze.

It is normally raced with two or three people. Its Portsmouth Yardstick DP-N average handicap is 82.5, close to a Shields, and only three sails are allowed: main, jib and spinnaker. Richard Sherwood, writing in 1994, placed it in the same market as the Etchells 22, Soling, Tempest and Ensign.

Paralympic boat and team-racing favorite

The Sonar is a World Sailing international class and was selected for Paralympic sailing at the 1996 Games. Disabled sailors adopted it because its crew-friendly layout lets them sail efficiently and safely while enjoying real performance, and adapted boats remain common. At the 2026 Sonar Midwinters in St. Petersburg, the class noted that a third of the nine-boat fleet was driven or crewed by disabled sailors; Kevin Holmberg's Fawkes won for the third year running.

Club fleets are the other pillar. The class names the Island Sailing Club in Cowes, Seawanhaka Corinthian Yacht Club in Oyster Bay, St. Petersburg Yacht Club and the New York Yacht Club's Newport station as clubs using the boat for weekend racing and high-level team racing. Brian Doyle won the 2025 North American Championship.

Buying a used Sonar sailboat for sale

Most Sonar sailboat for sale listings appear in class classifieds and through Sonar dealers rather than on big portals. Shumway Marine in Rochester, New York, a former builder, runs a used-Sonar page and warns that used boats turn over quickly. That makes it worth joining the class and telling the local fleet captain you are looking.

Start with the keel. The class builder now advertises a factory reinforced keel sump laminate, which tells you where older boats can need work. Then check the deck and cockpit sole for soft spots, the rudder and its bearings, spar condition, the trailer, and whether the boat has a valid measurement record. A boat with a recent sail inventory and a road-ready trailer is worth noticeably more than one without.

New Rondar or used Ontario?

A new Sonar costs about $45,000 with spars and a braked galvanized trailer, and Rondar quotes lead times of 60 to 90 days including roll-on, roll-off shipping to the nearest port. That buys a fair bottom and keel, minimum weight and no sump worries. A tidy used Ontario or Seidelmann hull at a fraction of the price is the better route for club racing and learn-to-race programs, provided the keel area is sound.

Running costs are low: $3,000 to $9,000 a year covers a mooring or dry sail spot, insurance, trailer upkeep, class dues and a periodic sail purchase.