Cal's Evals » DISCOVERY 50 CATRelease Date: 1/17/2011
Cals Evals Discovery 50
The specifications for this 50 foot cruising catamaran show it to be significantly heavier than the averages of 42 catamarans in the 46-47.5 foot waterline length range featured in the Multihull Dynamics, Inc. website. The displacement, taken from the designers website, is 47% above average and the upwind sail area is 2% below average, which will result in a slower but more stable boat. The specification, performance and stability numbers, followed in brackets by average values are:
Displacement: 14.5 long tons [9.87 tons]
Length overall: 50 ft. [48.82 ft.]
Waterline length: 46.75 ft. [46.64 ft.]
Overall beam: 25.17 ft. [26.43 ft.]
Hull length to beam ratio: 8.52 [10.79]
Beam between hull centerlines: 19.68 ft. [21.4 ft.]
Sail Area: 1281 sq. ft. [1371 sq. ft.]
Displacement-Length Ratio: 70.96 [48.68]
Sail Area Displacement Ratio: 20.13 [27.59]
Bridgedeck Clearance: 33 inches (3 higher than MSI standard)
Base Speed: 10.42 knots [11.64 knots]
Texel Rating: 169 
Bruce Number: 1.13 [1.31]
Stability Speed: 23.93 knots [20.81 knots]
The Sail Area/Displacement ratio is the telling factor for the boat being nearly 1.2 knots slower than average (Base Speed). Although the boat is slightly narrower than average (beam between hull centerlines), the greater displacement makes it stable as shown in Stability Speed. It is only fair to point out that the 44 boats in the comparison include Tektron 50 and Fastcat 525 designs on the very fast end and Manta 50 and Hughes 50 Motor Sailor on the slower end.
The Discovery 50 is clearly designed to be a cruising boat. Its Bruce Number places it well down in the Conservatively Rigged category using upwind sails. It is assumed to be fitted with low aspect ratio keels.
It can be seen on the Discovery Yachts website at www.discoveryyachts.com.
Calvin H. Markwood
Multihull Dynamics, Inc.
Contact Cal: firstname.lastname@example.org