The boat marked a deliberate break from O’Day’s traditionally conservative lines. By the mid-1980s, the company was pursuing sleeker, faster profiles with a stronger European influence.
Design and Construction
Briand gave the O’Day 40 a flatter underbody and finer entry, while carrying the beam well aft to provide plenty of form stability. The result is a more contemporary, performance-oriented hull than those of earlier O’Day models, with much greater speed potential and better manners off the wind.
The hull is a cored composite built with three-quarters of an inch of balsa, polyester resin, and biaxial fiberglass cloth. The composite decks use both balsa and plywood core. A structural grid manages rig loads, supported by fiberglass liners, plywood bulkheads, and longitudinal and athwartship members. These components were attached well, and serious structural concerns are rare. Fit and finish, however, are typical of entry-level boats from the 1980s.
A low cabin trunk slopes gradually toward the foredeck. Angled cabin sides meet wide side decks, providing secure footing when the boat is heeled. Rail-mounted stanchions also keep the lifelines clear of foot traffic. The foredeck has a large anchor locker, and the boat is fitted with a perforated aluminum toe rail.
Rig, Performance, and Handling
Most O’Day 40s were built as masthead sloops, with a deck-stepped mast and an aft cockpit. The sail plan is generous: the 100% foretriangle measures 392.69 square feet, while the mainsail adds 329.28 square feet, for a total of 721.97 square feet.
Displacement ranges from 18,000 to 18,500 pounds, with a ballast ratio near 40 percent. The sail-area-to-displacement ratio is around 16.3 to 16.9, and the displacement-length ratio is 214.
U.S. Sailing’s PHRF gives the O’Day 40 an average handicap of 114. That makes her 39 seconds per mile slower than a J/40 and 57 seconds behind the strictly cruising Island Packet 38. Reviewers describe her as a balanced boat with balanced handling—a capable passage-maker that combines comfort with respectable speed.
Cockpit and Accommodations
The O’Day 40 has impressive interior volume and is an excellent liveaboard candidate. Its two-cabin, two-head layout includes a forepeak with a V-berth. Alongside it are a port-side head and shower and a hanging locker to starboard.
In the main saloon, a U-shaped dinette and drop-leaf table sit to port, with a settee to starboard. The aft quarter-berth cabin contains a large athwartship double tucked beneath the cockpit.
Descriptions of the galley differ. One places a U-shaped galley to starboard; another describes a spacious galley aft to port, with a forward-facing navigation station opposite.
The deep cockpit seats its crew comfortably and includes lockers to port and starboard. At the stern, the transom carries a swim platform that was ahead of its time.
Auxiliary Power and Cruising Capacity
Most O’Day 40s were fitted with a Universal M-35 or M-40 diesel. A Westerbeke 46-horsepower engine is also documented. The engine sits beneath the companionway steps, and removing those steps and the starboard-side aft panels provides reasonable access.
Tankage is about 100 gallons of water and 40 gallons of fuel. Together with the large foredeck anchor locker, the boat’s capacity supports extended cruising.
Known Issues
On fin-keel models, a hairline crack may appear at the front of the keel-to-hull joint. Sometimes called the “O’Day Smile,” this crack may be confined to the gelcoat, but it can also indicate a more serious condition.
Unless remedial work has already been completed, these boats are likely to show some osmotic blistering below the waterline. Deck cracking and crazing are also quite common and, in severe cases, can affect structural integrity.
The Verdict
The O’Day 40 represents a mature design statement from a storied American marque working with European talent. It offers cruisers generous volume, stability, and good off-wind performance in a manageable 40-foot package. On the used market, however, the deck core and keel joint demand attention.
Pros
- Large interior volume and a liveaboard-friendly, two-cabin, two-head layout
- Performance-oriented hull with strong form stability and good off-wind manners
- Rare structural attachment problems and solid, grid-supported construction
Cons
- Common deck crazing and likely osmotic blistering below the waterline
- The fin-keel “smile” crack requires inspection
- Fit and finish are typical of modest 1980s production
