Design and Construction
The Sirius 31 has a solid, hand-laid fiberglass hull and a partly balsa-cored deck. Around the important openings for rigging and deck fittings, the deck is solid. A floating teak deck covers the structure, while a fixed windscreen provides genuine protection forward.
The yacht’s most distinctive underwater feature is a hump in the hull lines just ahead of the pronounced skeg. Schmidt borrowed the shape from whales to promote a well-behaved stall anchor. The skeg also contributes notable stability.
There’s no inner GRP shell, so incipient leaks reveal themselves early rather than remaining hidden behind liner panels. Construction is very solid, and the timber work is of high quality throughout, from the cockpit details to the dark teak wall panelling below.
History and Production
The first three hulls were built with the hump, but an oil-price shock in 1979 delayed further progress. Production then ran from the early 1980s until 1991.
Around 170 boats were completed in this hull form, roughly 70 of them in the original configuration. A deck-saloon version using the same hull appeared later and proved popular. Most Sirius 31s have a lead keel, although cast keels were used briefly at the start—and were already epoxy-coated at the time.
Rig and Handling
The Sirius 31 is a masthead sloop with a 13.0 m mast, a 21.5 m² mainsail, and a 29.9 m² Genoa I. A 70 m² gennaker or spinnaker was also available.
She came in three draught variants:
- A fixed keel drawing 1.65 m
- A shoaler fixed keel drawing 1.35 m
- A ballast centreboard with draught ranging from 0.9 to 2.1 m
At just under 4.3 sail deadweight, the Sirius 31 counts as a comparatively heavy cruising boat. Even so, owners report that she needs only 3 Beaufort to get moving and then sails very well and stably above that, handling waves comfortably. Period observers did note that the rudder feels somewhat cumbersome. All control lines lead aft to the deep, well-protected cockpit.
Accommodation
Below, beautifully finished woodwork surrounds a large central table in a classic saloon arrangement. Long Plexiglas panes originally lit the interior. The builder later replaced them with three oval, aluminium-framed windows, although some boats retain the earlier glazing.
Fixed doors take the place of loose bulkheads. In the compact wet room, a pull-out washbasin makes practical use of the available space. A pull-out navigation table above the starboard dog bunk is well suited to paper-chart work.
The companionway steps lift out to provide access to the Volvo 2002, which has dual-circuit cooling. Overall, the layout is well thought out, though the passages read as somewhat dark.
Known Issues
Osmosis isn’t considered a concern on this design, and the boats aren’t known for it. The teak deck, however, deserves critical inspection. It was very often fitted and can suffer when neglected.
Any later openings cut through the balsa-cored deck by previous owners may have been poorly sealed, creating a source of leaks. Old screwed windows can also weep. On centreboard versions, the board’s operation should be checked.
Refits and Ownership
At an owner’s request, the builder developed a stern extension as a retrofit kit, and it remains available from the yard today. The extension incorporated a swim ladder and step, quieted the engine, and improved the under-power stall.
Because the original shipyard still exists, parts supply and repairs remain practical for owners.
The Verdict
The Sirius 31 is a very solid, harmonious cruising yacht with many strengths and few real weaknesses. She suits sailors who value accessible construction, thoughtful accommodation, and a stable manner at sea over outright racing sparkle.
Pros
- Unusual whale-inspired hull hump for controlled stall, with stability from the skeg
- Solid, hand-laid hull with no inner shell to conceal problems
- High-quality timber interior with practical pull-out fixtures
- Deck-saloon and stern-extension options supported by the original yard
Cons
- Teak decks and old screwed windows require careful inspection
- Rudder described as somewhat cumbersome
- Interior passages read as somewhat dark
