Design and Construction
The German naval architecture firm Judel/Vrolijk & Co drew the 511 in the early 2000s. Both the hull and deck are solid fiberglass.
With a beam of nearly 15 feet and a length-to-beam ratio of 3.44, she is beamy for her length. Her displacement-length ratio of 220 places her firmly at the heavy, seakindly end of the cruising spectrum. A capsize screening value of 1.70 and a Motion Comfort Ratio of 38.7 reinforce the picture of a stable, volume-rich offshore yacht built to carry a load without punishing the crew.
The 33 percent ballast-displacement ratio, combined with a fin keel and skeg-hung rudder, points to predictable righting behavior rather than race-bred agility.
Rig and Handling
The 511 is a masthead sloop. Her sail-area-to-displacement ratio of 18.42 indicates a moderately powered rig suited to a heavy hull without requiring extreme sail handling. Theoretical hull speed is 8.9 knots.
An immersion rate of about 2,262 pounds per inch means she sits deep and changes trim slowly as stores and water come aboard—a trait that rewards careful loading. Standing- and running-rigging estimates in the design record specify 16 mm sheets throughout: roughly 50-foot jib and genoa sheets, a 127-foot mainsheet, and 112-foot spinnaker sheets. These are sized for the loads generated by the 511’s 1,388.54-square-foot sail area.
Accommodations
Below, the 511 offers above-average headroom for a yacht of this size. That fits with a hull whose 39-point comfort ratio and 166-gallon water capacity are intended for extended living aboard.
The beamy midbody behind the 3.44 length-to-beam ratio also provides the interior volume expected by a cruising family or two-couple crew in a 50-foot Najad. The available sources, however, don’t itemize the berth count or specific layout.
Verdict
The Najad 511 is a heavily built, beamy offshore cruiser from the marque’s Judel/Vrolijk era. Her design emphasizes stability and carrying capacity rather than speed. The ratios describe a yacht intended to look after her crew in weather and absorb the weight of long passages, while the masthead rig provides manageable power.
The trade-off is a heavy hull that won’t leap onto a plane and, given its immersion rate, rewards disciplined load management.
Pros
- Solid-fiberglass hull and deck from a recognized offshore design bureau
- High stability and comfort ratios for bluewater cruising
- Above-average interior headroom
- Large water capacity
Cons
- Heavy displacement limits responsiveness in light air
- Deep immersion rate demands careful provisioning and tank management
