Design and Construction
The hull is solid fibreglass, as is the deck, and the boat draws between 7.64 and 7.94 feet depending on load — a draft deep enough that she can only enter major marinas. The displacement-length ratio sits at 79, which classifies her among the "ultra light racers" of her era, while a length-to-beam ratio of 3.39 and a motion comfort ratio of 12.0 to 12.6 place her firmly in the territory of a lively, responsive hull rather than a slow, voluminous passage-maker. Her capsize screening value of 2.38 meant she would not have been accepted to participate in ocean races under that metric, a reminder that the design was conceived for coastal and performance cruising rather than bluewater minima. The wetted surface of the bottom is about 548 square feet, and the immersion rate runs roughly 1,561 pounds per inch, so she responds quickly to added load and sail trimming alike.
Rig and Handling
What distinguishes the Rainbow 42 on paper is her rig. She carries a fractional sloop layout and, by one assessment, more rig than 100 percent of all similar sailboats, which indicates that the boat is significantly overrigged. The sail area for mainsail and jib totals 808 square feet, and the sail-area-to-displacement ratio runs 30.4 on the ISO reference sail, climbing to 34.9 with a 135 percent genoa. That overdriven sail plan, paired with the ultralight displacement, produces a Relative Speed Performance figure of 97 and a theoretical displacement-hull maximum of 8.1 knots. The running rig is sized generously: halyards for main, jib, and spinnaker each run 133.4 feet at a half-inch diameter, while sheets — jib, genoa, and mainsheet — are 14 mm line, with the mainsheet alone 104.2 feet long. A buyer or crew should expect a boat that accelerates in modest breeze and demands disciplined sail handling rather than a sluggish, forgiving hull.
Accommodations
The available authority material provides no descriptive detail on interior arrangement, berth count, or joinerwork, and the builder's background offers no elaboration. What can be said with confidence is that the 12.3-foot beam and 42-foot length provide a contemporary cruising footprint, and the 37 percent ballast ratio with 3,108 pounds of lead in a bulb fin suggests a stiff platform once heeled. The motion comfort ratio in the low teens reinforces that she is built to move with the sea rather than smother it.
Known Issues
The single design-level caveat is the deep draft — between 7.64 and 7.94 feet with load — which historically restricted these boats to major marinas and excluded many shallow anchorages and smaller harbours. That is a constraint of the bulb-fin configuration rather than a defect, but it shaped where the fleet could reasonably cruise.
Refits and Ownership
The guiding rig dimensions form a useful baseline for any re-rigging or line replacement: halyards at 133.4 feet by half-inch, sheets at 14 mm with the mainsheet 104.2 feet long, and control lines such as the cunningham and kicking strap at 36-foot lengths. Owners maintaining the original overdriven rig should plan line inventories around those figures rather than typical 40-foot-boat assumptions.
The Verdict
The Rainbow 42 is a Harter-designed, Farsø-built performance cruiser that trades volume and offshore certification for sparkling light-air speed and a responsive, ultralight hull. She is a specialist's boat — quick, stiff, and demanding of a crew that enjoys sail power over motoring — and her draft will dictate her cruising range more than any accommodation limit.
Pros
- Ultralight displacement (DL 79) with overdriven rig for high speed potential
- Stiff, lead-ballasted bulb fin with 37 percent ballast ratio
- Generous, well-documented running-rig dimensions for easy maintenance
Cons
- Deep draft (7.64–7.94 ft) limits marina and anchorage access
- Capsize screening of 2.38 excludes ocean-race acceptance
