Design and Construction
Marine Projects built the S31 with a solid fiberglass hull, a balsa-cored deck typical of the era, twin keels, and a skeg-hung rudder. She displaces 10,617 pounds and carries 3,650 pounds of iron ballast. Her ballast-displacement ratio of 34.38 places her among moderately ballasted cruisers, while a displacement-length ratio of 254.4 reflects a volume-driven design.
Accommodations
The large aft cabin spans the full width of the boat. Even with its full-size double berth, there is still plenty of space. It also has its own hatchway to the cockpit.
The forecabin sleeps two, and the saloon settees provide another two berths, bringing the total to six.
Rig, Engine, and Handling
The S31 carries a masthead sloop rig with 422 square feet of sail area. Auxiliary power comes from a 19-horsepower Volvo Penta MD2020 diesel driving through a saildrive.
Period tests by Yachting Monthly, Yachting World, and Yachts & Equipment in 1994 documented her launch behavior. For access to the water, the center section of the transom folds down to form steps.
Maintenance and Known Issues
The MD2020’s saildrive leg is a sealed underwater unit. Its rubber boot and shaft seal are the wear points to understand on this design.
The folding transom steps are another wear item when used frequently for swimming, though they are straightforward to maintain.
Ownership
With 145 boats built, the S31 has a small fleet, which limits the choice available to buyers.
The Verdict
The Moody S31 is a compact cruiser that trades sportiness for a practical layout and a full-beam aft cabin. She is best suited to couples or small families who value interior volume and the flexibility of twin keels.
Pros
- Full-width aft cabin with ample space and its own cockpit hatchway
- Six berths across the forecabin, aft cabin, and saloon settees
- Solid fiberglass hull with a balsa-cored deck
- Folding transom steps for access to the water
Cons
- Saildrive boot and shaft seal require attention
- Small fleet limits buyers’ choice
- Moderate ballast favors comfort over pace
