Design and Construction
The Sirocco 31 has a length-to-beam ratio of 3.35 and displaces 6,500 pounds. Of that, 3,040 pounds is iron ballast, giving a ballast ratio of 47 percent. Along with a capsize screening value of 1.98, these figures place her firmly in the cruiser-racer band rather than the offshore expedition class.
Both the hull and deck are solid fiberglass, and the wetted surface is about 269 square feet. Her displacement-length ratio of 210 earns the “moderate racer” categorization. A Motion Comfort Ratio of 19.7 suggests a tolerable, though not especially soft, motion in a seaway.
The theoretical hull speed for a displacement hull with this waterline is 6.6 knots, although the calculated maximum speed is closer to 4.5 knots in practice.
Rig and Handling
The Sirocco 31 carries a masthead rig and has a sail-area-to-displacement ratio of 14.46. That figure points to modest drive in light air rather than sparkling acceleration.
Her running rig follows the masthead convention of the period: 31-foot jib and genoa sheets at half-inch diameter, a 77.5-foot mainsheet of the same diameter, and 68.2-foot spinnaker sheets.
The fin keel and skeg-hung rudder should allow her to pivot reasonably within her own length. Her relatively shallow, load-dependent draft also makes her forgiving in crowded anchorages. An immersion rate of 774 pounds per inch means she sits sensibly to her ballast and doesn’t squat dramatically when loaded with cruising stores.
Accommodations
The class record provides no interior arrangement, berth count, or tankage details for this design. From the available exterior dimensions, her 9.25-foot beam and 24-foot waterline give her the hull volume typical of a 31-foot cruiser-racer of the era. The specific accommodation layout, however, must be assessed hull by hull.
Known Issues and Maintenance
The Sirocco 31 shows no structural defects, osmotic blistering, or rigging failures in service. For a fiberglass production boat from the 1970s, the absence of flagged problems is itself noteworthy.
There are no class-wide refit campaigns or recurring maintenance regimes specific to the Sirocco 31. The ownership record is limited to her Spanish construction and straightforward, solid-fiberglass build. That implies the usual maintenance associated with a solid-glass hull of the period rather than concerns about core saturation.
The Verdict
The Sirocco 31 is a Primrose-designed, Ballina Marine-built fiberglass sloop that sits comfortably in the moderate-racer category without pretending to offshore-racer credentials. Her numbers describe a predictable, marina-friendly cruiser with a sensible ballast ratio and forgiving draft. The main drawback is the lack of published information about her accommodation plan and tankage.
Pros
- Designed by Angus S. Primrose, a recognized British naval architect
- Solid fiberglass hull and deck
- Iron ballast and a 47 percent ballast ratio
- Load-dependent draft near 5.5 feet eases marina access
- No class-wide structural or rigging defects in service
Cons
- Modest light-air drive from a 14.46 sail-area-to-displacement ratio
- No published accommodation plan or tankage details
- Calculated top speed of 4.5 knots, below the theoretical hull speed
