Design and Construction
The hull is a single solid-fiberglass molding mated to a deck that carries balsa core in low-load areas and plywood where stiffness matters, the two joined on a flange and locked both chemically and with fasteners. Lead ballast lives inside the keel cavity and is glassed over, while teak-and-plywood bulkheads are well tabbed to the shell. The rudder hangs behind a large full skeg on a beefy stainless shaft with a foam core under thin glass. Above the waterline the sheerline reads as a quiet mid-1970s dip with a nicely raked stem, and the forefoot runs aft into a sweptback fin. A rubrail was a welcome option. Below the waterline, early boats used gate valves on thru-hulls, but from 1980 O'Day switched to bronze through-hull fittings — a useful datum for anyone reading a hull's birth date off its plumbing.
Rig and Handling
The sloop rig is low aspect by modern measure, with a 47-foot air draft and a long boom carrying a moderate 594 square feet of working sail. The single-spreader mast is deck-stepped, with double lower side stays and stainless rigging closed by swaged terminals. Owners should note those original terminals: if they survive, they are living on borrowed time and need replacement. Sail handling is straightforward — a mainsheet led aft to a triangular block-and-tackle on the aft deck and worked by a small winch gives clean end-boom sheeting clear of the companionway, while genoa tracks sit outboard of the cockpit with turning blocks aft. Jiffy reefing and two reef points in the main make shorthanded breeze management simple. Underway the 37 tracks well and stays dry upwind, and owners say she sails comfortably on autopilot, finding her best stride once the wind builds rather than in the light stuff where she wants coaxing.
Accommodations
Step down and the small galley is to port with a two-burner alcohol stove, double stainless sinks — one annoyingly shallow — and a fairly large if modestly insulated icebox. Opposite sits a small chart table. The main cabin carries opposing settees around a drop-leaf table, teak joinery that is simple but neatly executed, overhead grab rails, and 6-foot-4-inch headroom. Forward, a V-berth with filler cushion sits behind flimsy folding doors and shares a compact but complete head; a generous hanging locker stands to starboard. The boat's defining space is the aft cabin: a roomy athwartships double with storage beneath and a private fiberglass-lined head and shower. The wheel pedestal does crowd the aft-cabin threshold, and the deep cockpit that one owner called cozy lends a real sense of security.
Known Issues
Owners reported the original hatches and especially the plastic portlights want upgrading, and in most cases outright replacement. The flush forward hatch leaks, and some boats with forward deck prisms or skylights saw those leak as well. Chainplates sit mid-narrow-side-deck and are awkward to reach from inside. The cast single bow roller is a touch undersized, and engine access behind both companionways is poorer than it ought to be — reaching the stuffing box is genuinely difficult, though one owner solved it with a dripless replacement.
Refits and Ownership
The standard four-cylinder 32-horsepower Universal diesel turns a 2:1 reduction gear and sips fuel gently; the aluminum tank held 28 gallons, good for close to 300 miles under power. Engine room access does exist through the cockpit seat lockers and aft cabin, but the tight stuffing-box path is the real refit prompt. Swaged rigging replacement, hatch and portlight renewal, and a proper bow roller are the common early ownership jobs. The production run built hundreds before the model was phased out in 1984.
The Verdict
The O'Day 37 is a thoughtfully laid-out small center-cockpit cruiser that behaves like a sailboat, not a trawler with sails. She is stiff, seakindly, and blessed with a private aft suite that defined her appeal, though light-air performance and a few access and sealing weak points ask for an owner's attention.
Pros
- Genuine center-cockpit layout under 40 feet with a large private aft double and head
- Solid glass hull, lead ballast glassed into the keel, well-tabbed bulkheads
- End-boom mainsheet and aft-led controls keep the cockpit clear
- Tracks well, dry upwind, sails steadily on autopilot
Cons
- Original hatches and plastic ports leak and need replacement
- Poor engine and stuffing-box access
- Undersized single bow roller
- Swaged terminals in original rigging are a replacement item
