Design and Construction
Ericus Gerhardus van de Stadt's hull is solid fiberglass, as is the deck, built by Jupiter Yachts though records note the boat has also been produced at other yards. The 40 percent ballast-to-displacement ratio and 2.13 capsize screening value tell the story: at 2.13 the capsize screening figure falls outside the threshold accepted for ocean racing anchor, which marks her as a coastal and inshore performer rather than a bluewater contender. Her displacement-length ratio of 221 classifies her among moderate racers, and two-thirds of comparable designs are heavier, so she sits light on the water for her length. The immersion rate of about 895 pounds per inch means she loads predictably, and the 2.83 length-to-beam ratio gives her a roomy plan for a 30-footer — more spacious than 76 percent of similar designs by that measure.
Rig and Handling
The masthead rig carries an ISO 8666 reference sail area giving a sail-area-to-displacement ratio of 16.4, rising to 19.7 with a 135 percent genoa, and that higher figure helps explain why she is calculated to be quicker than 54 percent of similar boats in light wind. Her theoretical hull speed is 6.7 knots, while the calculated maximum under engine power is about 4.5 knots through the shaft-drive transmission. The standing and running rigging follow predictable masthead proportions: mainsail, jib/genoa, and spinnaker halyards each run about 87.5 feet at 5/16 inch diameter, the mainsheet is 73.5 feet of 3/8 inch line, and jib and genoa sheets are 29.4 feet of 3/8 inch. A Motion Comfort Ratio of 19.4 puts her above 31 percent of similar designs for ride quality — not plush, but credible for a moderate racer of this size.
Accommodations
Below, the boat is equipped with five berths, a count that fits the beamy hull and supports weekend cruising or a small racing crew. The generous length-to-beam ratio that ranks her roomier than three-quarters of her peers translates directly into usable interior volume rather than merely deck spread, which is the sort of proportion that makes a 30-foot boat feel larger than her length suggests.
The Verdict
The Jupiter 30 is a van de Stadt–penned moderate racer with a light, roomy hull and a masthead rig that performs respectably in light air. Her capsize screening value excludes her from ocean racing, and her comfort ratio is middling, but for inshore racing and coastal weekends she offers a well-proportioned, solidly built platform.
Pros
- Roomy for her size, exceeding 76 percent of similar designs in space by length-to-beam ratio
- Light, moderate-racer displacement with good light-wind speed potential under genoa
- Solid fiberglass hull and deck from Jupiter Yachts' early-1980s build
Cons
- Capsize screening value of 2.13 bars her from ocean racing
- Comfort ratio better than only 31 percent of comparable boats
- Engine speed limited to about 4.5 knots
