Design and Construction
The Sirius 40 DS displaces roughly 11 tonnes and carries a 7,500-pound ballast plank. Beam is close to 13.4 feet, and the waterline measures about 36.6 feet.
The hull is hand-laid fiberglass and built in a one-piece mould. Its laminate includes vinylester gelcoat and resin, fibreglass mats, and rovings. Above the waterline, a vacuum-adhered Corecell M-foam sandwich adds stiffness without excessive weight. Parts of the deck also use foam-sandwich construction. The hull-deck connection and all bulkheads are laminated from every side, creating a single monocoque structure.
The keel carries about 3.45 tonnes of cast iron, or an optional hardened lead bulb. It is glued and screwed to the hull with fourteen 20 mm stainless steel bolts passing through steel reinforcement, while massively laminated bottom floor sections spread the loads.
Below the waterline, the finish consists of one layer of epoxy primer and hard antifouling. Two waterline stripes are applied in the owner’s chosen colour.
A 48° North reviewer found a massive steel rod connecting a deck fitting directly to an athwartships stringer in the midship-cabin closet. The detail underscores how this semi-custom hull is engineered for real offshore loads.
Keel and Draft Options
The range of ballast arrangements sets the 40 DS apart. The standard single fin draws 7.5 feet, while optional fixed shoal-draft versions draw 6.6 or 5.7 feet. The more unusual choices are the swing keel and twin keel.
The swing keel is a real centreboard that raises and lowers all the ballast, providing a draft range of about 3.1 to 8.0 feet. Its box is laminated as an integral part of the hull. The builder describes the mechanism as very reliable and safe, but also complex.
The twin-keel version allows the boat to sit upright on tidal flats every day, rather than treating drying out as a novelty. 48° North sailed this configuration and reported that it was structurally strong and stable enough to support the boat and its contents on land twice a day in perpetuity. The reviewer also found no compromise in sailing performance or tacking angles compared with the fixed keel.
Rig, Steering, and Handling
The Sirius 40 DS carries a 2-spreader aluminium Selden mast, a furling forestay, and a self-tacking jib system. One reviewer also noted a conventionally sheeted genoa arranged in Solent-rig fashion. A carbon-performance rig is available for owners seeking more pace.
All active halyards and trim lines lead aft to the cockpit, running through stoppers into a halyard box served by a single self-tailing winch. This arrangement makes short-handed sailing practical. The main boom has two single-line reefing systems and a kicking strap.
With a sail-area-to-displacement ratio near 4.0 using the self-tacking jib and 4.8 with the genoa, the design is no light-air rocket. However, the broad beam and 15.9 SA/D keep her honest upwind and on a reach.
Steering is through a pre-balanced, half-skegged rudder controlled by a burly, centreline-hinged wheel. An interior helm station also allows the crew to steer from the saloon in foul weather.
Saloon and Accommodation
The deck-saloon layout is the heart of the boat. A raised dinette sits to port, while the large saloon seats six adults around an extending table. The space makes full use of the 360-degree glazing and 1.95 m headroom. The double-use of raised and lower space gives more room than expected on any 47-footer.
Owners have requested more than eight interior plans. Choices range from 2+2 to 6+2 berths and include a lower-lounge version or an office. The builder says a large workshop and a large central cabin can be fitted together—a first for Sirius.
To port, a mid-ship berth is tucked beneath the saloon. It offers one of the largest double bunks afloat and the least boat motion. The aft-most dinette bench hinges out of the way to reveal a passage into a concealed workshop and systems room with a workbench. In some layouts, this space can also be entered directly from an aft cabin.
Four deep underfloor compartments provide substantial room for provisions and spares. The compartment in front of the galley extends nearly three feet down.
The galley includes a two-burner, half-gimbaled stove with an oven, a 130-litre fridge, a double sink, and pressurized water. Two heads and more than 400 litres of water tankage support extended living aboard.
Equipment and Ownership
Every Sirius 40 DS is built to the owner’s requirements, making it a pure semi-custom boat; no two examples are fitted identically. The builder offers personalised onboard and deck stowage beyond expectation.
Standard equipment is generous. It includes a Rocna anchor with 50 m of calibrated chain and an electric windlass, a Flexiteek cockpit, and a fold-down transom door. The specified engine is a Volvo Penta D2-55 saildrive, paired with a 53-gallon diesel capacity.
The swing keel is the one system a buyer should plan to understand and maintain because of its complexity. The fixed- and twin-keel versions avoid that system entirely.
Torsten Schmidt, owner of Sirius, spent seven weeks living aboard nonstop, an indication of how the firm views the boat’s liveaboard credentials.
The Verdict
The Sirius 40 DS is a thoughtfully engineered semi-custom cruiser. Its deck-saloon volume, flexible interior plans, and genuine shallow-draft or drying-out options are unusual in a 40-foot bluewater hull. It is solidly built and comfortably appointed for long passages, although the swing keel deserves respect as a complex system.
Pros
- Multiple keel options, including a true swing keel and a twin-keel arrangement designed for daily drying out
- Exceptional semi-custom layout flexibility, including the option to combine a workshop with a large central cabin
- Strong, thoroughly laminated hull and deck structure, with substantial keel-bolt reinforcement
- Raised saloon with 360-degree views and an unusually calm mid-ship berth
Cons
- The swing keel is described as reliable, but it remains complex technology to own
- The displacement and moderate sail plan make the boat no light-air rocket
- The blocky, high-freeboard hull form won’t appeal to classicist eyes
