Cal's Evals » SUNREEF 70

Release Date: 1/19/2005

Sunreef 70

This 70 foot cruising catamaran is one of a large stable of luxury cruising catamarans by Sunreef Yachts ranging in length from 62 to 146 feet. They can be viewed on their website at

The numerical evaluation of the Sunreef 70 is shown below, in comparison with 23 other cruising catamarans with waterline lengths between 65 and 75 feet. The first number is the value for the Sunreef 70. The numbers in brackets are averages for the boats in the comparison followed by the trend-line values at a 70 foot waterline length for over 900 catamarans in the Multihull Dynamics, Inc. database.

Length overall: 70 feet [71.52 average, 70 trend-line]

Waterline length: 64.28 feet [68.67 average, 70 trend-line]

Beam: 34 feet [35.36 average, 35 trend-line]

Displacement: 50 long tons [30.6 average, 25 trend-line]

Upwind Sail Area: 2099 sq. ft. [2680 average, 2600 trend-line]

Displacement-Length Ratio: 94.15 [47.55 average, 39 trend-line]

Sail Area-Displacement Ratio: 14.45 [26.36 average, 28.21 trend-line]

Beam between hull centerlines: 23.53 feet [28.54 average, 30 trend-line]

Base Speed: 10.63 knots [13.62 average, 14.2 trend-line]

Texel Rating: 1145 [110 average, 105 trend-line]

Bruce Number: 0.95 [1.28 average, 1.26 trend-line]

Stability Speed: 37.69 knots [26.74 average, 25.6 trend-line]

Base Speed is about 28% below average as a direct results of the boat being considerably heavier and lower powered (sail area) than most of the others. For the same reasons, however, Stability Speed is nearly 41% above average for boats of this size. The Sail Area-Displacement Ratio is a direct indicator of both of these features.

The designer points out that boat construction is always about compromising. [A] 70 footer, made up to highest comfort standards, with all sort of equipment like a/c, generators etc, being a comfortable, safe and easy to handle vessel will never be a light racer.

Calvin H. Markwood
Engineering Analyst
Multihull Dynamics, Inc.

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