Design and Construction
Enderlein’s hull runs 24 feet 8 inches on the waterline and 9 feet 5 inches in beam, drawing 4 feet 7 inches with a displacement of 9,250 pounds and a lead ballast keel of 4,200 pounds. The keel is a moulded steel unit set into a deep GRP bilge pocket, and period surveys describe the full keel with internal ballast encapsulated in abundant layers of uni-directional cloth and resin, its laminate thickness reaching 25 mm at the lowest section, tapering to 15 mm at the waterline and 10 mm above it. The deck and hull are joined by a teak cover-board at the gunwale, a method praised as both elegant and structurally sound. Below, the interior is executed almost entirely in solid mahogany, and one circumnavigating example retired to a museum had never received any special structural strengthening for its three and a half global circuits.
Rig and Handling
The mast is a robust single-spreader Selden section stepped on deck, carrying 430 square feet of sail with a working jib. In professional assessment she is neither especially fast nor a high pointer, yet test sailors found her a very sturdy boat able to tackle challenging voyages comfortably. The smallest boat that will take you anywhere, in one reviewer’s phrase, she has sailed from the Labrador to the Beaufort to the Bering Seas. The original engine was a 25 hp twin-cylinder Volvo MD 2B, later specified as a Volvo Penta MD 11 C of 23 hp, and that early installation pushed her at 7.2 knots at 2,300 rpm.
Accommodations
Below decks the layout is super-classic and remarkably roomy for the length. The navigator’s bunk tucks behind the chart table to starboard, while the galley to port forms a sensible L-shape with the sink placed centrally near the companionway steps. Amidships, an L-shaped dinette to port converts to a twin, and a starboard settee doubles as a bunk; upholstered backrests swing up at night to form generously sized sleeping spaces. The saloon is divided from the forward cabin by the head, with a sliding door aft and twin swinging doors forward, and storage is generous with doored lockers, drawers, and a large two-part hanging locker in the passageway. Period reviews call the interiors cosy, rational, and incredibly spacious.
Known Issues and Ownership Notes
Owners re-fitting these boats report original through-hulls fitted with gate valves as seacocks rather than ball valves, and evidence of water entering from U-bolt-style lower shroud plates. Aged boats have shown a pungent smell emanating from the head and its holding tank. The cockpit is well protected by a permanent shockproof-glass windscreen and bikini top — a Hallberg-Rassy hallmark — and one long-term owner added a hard top for even better shelter. Refitters have swapped the original Origo alcohol stove and icebox for Engel fridges, added solar, and replaced ground tackle with larger anchors and longer chain.
The Verdict
The Monsun 31 earns her reputation as a capable small voyager through sheer structural honesty and a timeless interior. She is not quick, but she is built to go far and stay dry.
Pros
- Proven global voyager with 904 built and museum-retired circumnavigators
- Solid mahogany interior and encapsulated full keel with heavy layup
- Protected cockpit and spacious, rational classic layout
Cons
- Original gate-valve seacocks and U-bolt shroud plates need inspection
- Modest speed and pointing ability under sail
- Head and tank odors on unrefitted boats
