Cal's Evals » St Francis 44 MKII

Release Date: 11/23/2005

St. Francis 44 Mk II

This 44 foot cruising catamaran is a bit of a puzzle to analyze because she has a significant bow overhang, unlike most of her sister ships. Thus, it is hard to know whether to compare her with other catamarans in the 44 foot overall length range or 39 foot waterline range. When faced with that, it is always interesting to do both. So in the data to follow, the first value is for the SF44, the second [in brackets] is the average of 34 boats with overall length between 44 and 45 feet and the third is the average of 50 boats with 39-40 foot waterline length:

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Length overall: 44.17 feet [44.42 for the similar overall length boats, 41.38 for the similar waterline length boats]

Waterline length: 39.67 [42.06 ft, 39.40 ft]

Displacement: 6.89 tons [7.78T, 6.65T]

Sail Area: 1238 sq. ft. [1032 sq. ft., 1007 sq. ft.]

Displacement-Length Ratio: 55.20 [52.94, 54.28]

Sail Area-Displacement Ratio: 28.69 [25.22, 27.42]

Beam between hull centerlines: 19.48 feet [19.99 ft., 18.86 ft.]

Base Speed: 11.45 knots [10.76 knots, 10.73 knots]

Texel Rating: 122 [117, 116]

Bruce Number: 1.42 [1.25, 1.30]

Stability Speed: 16.95 knots [21.29 knots, 19.43 knots]

St. Francis 44 Mk II has a displacement that is mid-way between the two groups of boats, but has a sail area that is significantly larger than both. Thus, the sail area to displacement ratio is high, giving rise to the higher base speed than either group, with it attendant larger handicap represented by the Texel Rating. As expected, with average beam between hull centerlines, the greater sail area results in lower stability speed then either group.

The Multihull Maven website description of this boat states While owners won't break any speed records on this boat, she sails well and can easily be operated shorthanded, and turns out good average daily runs for a cruiser of her class.

The numbers pretty well confirm this. The CSK Patty Cat II has a base speed of 12.10 knots, the highest in the 44 foot LOA group of boats, while the Fusion 40 Sport has a base speed of 13.92 knots, the highest in the 39 foot LWL group.

Calvin H. Markwood
Engineering Analyst
Multihull Dynamics, Inc.

Contact Cal: multihull.analysis@comcast.net