Design and Construction
The hull measures 24 feet 8 inches on the waterline, with a beam of 9 feet 5 inches and a draft of 4 feet 7 inches. Displacement is 9,250 pounds, including a 4,200-pound lead ballast keel.
The keel is a moulded steel unit set into a deep GRP bilge pocket. Period surveys describe the full keel and internal ballast as encapsulated in abundant layers of unidirectional cloth and resin. Laminate thickness reaches 25 mm at the lowest section, tapering to 15 mm at the waterline and 10 mm above it.
The hull and deck are joined beneath a teak cover-board at the gunwale, a method praised as both elegant and structurally sound. Below, the interior is finished almost entirely in solid mahogany. One circumnavigating Monsun, now retired to a museum, completed three and a half circuits of the globe without receiving any special structural strengthening.
Rig, Engine, and Handling
The mast is a robust, deck-stepped, single-spreader Selden section. With a working jib, the boat carries 430 square feet of sail.
Professional assessments describe the Monsun as neither especially fast nor a high pointer. Test sailors nevertheless found her a very sturdy boat, able to tackle challenging voyages comfortably. One reviewer called her “The smallest boat that will take you anywhere,” and the model has sailed from the Labrador to the Beaufort and Bering Seas.
The original engine was a 25 hp, twin-cylinder Volvo MD 2B. It was later specified as a 23 hp Volvo Penta MD 11 C. The early installation pushed the boat at 7.2 knots at 2,300 rpm.
Accommodation
Below decks, the layout is remarkably roomy for the boat’s length and thoroughly traditional. To starboard, the navigator’s bunk tucks behind the chart table. Opposite, the port-side galley forms a practical L shape, with the sink positioned centrally near the companionway steps.
Amidships, an L-shaped dinette to port converts into a twin berth. The starboard settee also doubles as a bunk, and the upholstered backrests swing up at night to create generously sized sleeping spaces.
The head separates the saloon from the forward cabin, with a sliding door aft and twin swinging doors forward. Stowage is generous, including doored lockers, drawers, and a large two-part hanging locker in the passageway. Period reviews describe the interior as cosy, rational, and incredibly spacious.
Cockpit and Refit Notes
A permanent shockproof-glass windscreen and bikini top protect the cockpit, a hallmark of Hallberg-Rassy yachts. One long-term owner added a hard top for even better shelter.
Refitters have replaced the original Origo alcohol stove and icebox with Engel fridges, added solar installations, and upgraded the ground tackle with larger anchors and longer chain.
Known Issues
Owners refitting these boats report that the original through-hulls used gate valves as seacocks rather than ball valves. They have also found evidence of water entering around the U-bolt-style lower shroud plates. Some older boats have developed a pungent smell from the head and its holding tank.
The Verdict
The Monsun 31 earns her reputation as a capable small voyager through straightforward, substantial construction and a timeless interior. She isn’t quick, but she was built to go far and keep her crew dry.
Pros
- Proven global voyager, with 904 built and circumnavigating examples retired to museums
- Solid mahogany interior
- Encapsulated full keel with a heavy layup
- Protected cockpit
- Spacious, rational, traditional layout
Cons
- Original gate-valve seacocks and U-bolt shroud plates need inspection
- Modest speed and pointing ability under sail
- Head and holding-tank odours on unrefitted boats
