Only 10 to 15 Mk IIIs were built in 1977 and 1978. This rare variant refined the earlier Cal 46 and Cal 2-46 while retaining the series’ reputation for blue-water cruising and performance.
Design and Construction
The Cal 46 line began with the original, sloop-rigged Cal Cruising 46 in 1967. The redesigned Cal 2-46 followed from 1973 to 1976, and the virtually identical Cal 3-46 was built in 1977 and 1978. The latter differed only in minor interior changes.
Across the family, the hull was hand-laid in solid fiberglass using cloth and woven roving. Lead ballast was precast in a mold, lowered into the fiberglass keel cavity, and glassed over. Wood bulkheads and structural furniture were fiberglassed to the hull. The hull-to-deck joint was sealed with 3M 5200 and through-bolted with 1/4-inch machine screws, forming a double-thick seam.
The boat combines a large spade rudder with a long cruising keel cut away significantly at the forefoot, giving it a balance of maneuverability and tracking ability. Its shoal five-foot draft and relatively high center of gravity mandated a short rig.
Rig, Performance, and Handling
The Mk III carries a ketch rig, which became available across the series in 1973 after the original sloop configuration. The mainmast foretriangle measures 48-foot I and 18-foot J, while the mizzen has a 25-foot P2 and 9.5-foot E2.
Total sail area is around 855 square feet with the 313-square-foot mainsail and 424-square-foot jib. Owners could also fly a 150-percent genoa of 657 square feet or a 1,085-square-foot asymmetrical spinnaker for downwind sailing. A 152-square-foot storm jib was intended for heavy air.
With a 37-foot-6-inch waterline and 30,000-pound displacement, the Cal 46 has a displacement-length ratio in the moderate range. The hull drives at roughly 8.5 knots, and the series’ Perkins diesel gives a cruising range near 1,200 miles.
Accommodations
Lapworth’s layout broke with convention for its era. Center cockpits were unusual in the late 1960s and early 1970s, and the Cal 46’s raised deckhouse provided 270-degree visibility while sheltering the dinette and galley.
A stateroom at each end allowed two couples to cruise in privacy without disturbing the dinette. The original arrangement had V-berths and a private head forward, the raised deckhouse amidships, and a large aft living space with settees and a sofa bed.
Interior joinerwork is Burmese teak, with vinyl-covered overhead panels. Owners across all Cal 46 variants are unanimous in praising the large engine room and its standing headroom—a real advantage when servicing a 30,000-pound yacht.
Machinery
The Perkins 4-236 diesel, described as excellent and installed in an 85-horsepower form on the series, provides strong motivation against drifters. The original Warner V-drive, however, adds expense and complication to the drivetrain.
Known Issues
Not every detail has aged well. Practical Sailor found that the series’ large glazed panels looked fragile and let water in, although their size was progressively reduced after the original 46.
Owners also identify the wooden spreaders as a maintenance item. One owner reported that the black iron fuel tanks rotted out at 15 years. A Cal 2-46 brochure describes two 10-gauge steel fuel tanks with a combined capacity of 135 gallons, while the water tanks—at least in later models—are stainless steel.
Refits and Ownership
With its improved interior layout and efforts to reduce maintenance issues found in its predecessors, the Mk III is the most evolved version of the line. Its plywood-cored deck was structurally sound according to owner observation, while the bonded hull-to-deck seam reflects construction intended for distance cruising.
Its rarity presents a practical drawback. With only 10 to 15 Mk IIIs produced, any refit must account for scarce model-specific parts.
The Verdict
The Cal 3-46 is a scarce, well-considered finale to Lapworth’s Cal 46 series. It combines a shoal-draft, center-cockpit ketch configuration with genuine blue-water credentials, a bright deckhouse, and an engine room that owners particularly value.
Its weaknesses are concentrated in period-typical details—leaky windows, wooden spreaders, and vulnerable iron tanks—that a careful buyer can address. The complicated original V-drive is another drawback. For a cruiser seeking a distinctive American ketch from the 1970s, the Mk III may reward a patient search.
Pros
- Refined final version of the Cal 46 line, with an improved layout
- Center cockpit and raised deckhouse with 270-degree visibility
- Large engine room with standing headroom, praised by owners
- Solid, hand-laid fiberglass hull with glassed-in lead ballast
- Blue-water reputation, roughly 8.5-knot hull speed, and 1,200-mile range
Cons
- Large windows prone to weakness and leaks
- Wooden spreaders require continuing attention
- Black iron fuel tanks reported to have rotted out at 15 years
- Rare production run of 10 to 15 boats complicates parts sourcing
- Original V-drive adds expense and complication
