Cal's Evals » DEAN 441

Release Date: 1/18/2011

Cals Evals Dean 441

 

This catamaran is a conservative cruising sailboat. The specification, performance and stability figures for comparison come from the averages of 31 cruising catamarans in the 42-44 foot waterline length. These boats are featured in the Multihull Dynamics, Inc. website. The analysis elements, followed in brackets by the average values, are:

 

Displacement: 11.81 tons [8.19 tons]

 

Length Overall: 43.67 feet [Range 42-47 feet]

 

Length at Waterline: 43 feet [43.25 Feet]

 

Sail Area (Main plus genoa): 1345 sq. ft. [1107 sq. ft.]

 

Displacement Length Ratio: 74.27 [50.72]

 

Sail AreaDisplacement Ratio: 24.24 [26.13]

 

Beam between hull centerlines: 18.34 ft. [20.26 ft.]

 

Base Speed: 10.81 knots [11.06 knots]

 

Texel Rating: 119 [114]

 

Bruce Number: 1.24 [1.28]

 

Stability Speed: 20.02 knots [20.72 knots]

 

The Dean 441 is considerably heavier than its peers, but has considerably more sail area. The sail area-displacement ratio shows, however, that the sail area will not bring the boat up to average performance. The Base Speed bears this out. The Dean 441 is also narrower than the other boats, with a beam between hull centerlines that is nearly two feet narrower. So despite her heavy weight and comparatively modest sail area, her Stability Speed is no better than average.

 

The plans and photos on the Dean Catamarans website reveal another characteristic that I am concerned will adversely affect performance over and above the low sail area to displacement ratio. That is, the boat appears to have much of its weight forward, with the widest part of the hulls well ahead of the center of the boat. This would cause the hulls to form larger bow waves than more conventional catamaran design. The photos of the boat sailing show a bone in her teeth, adding to suspicion of too much up front. A bow wave would increase hull drag through squatting and wave interference between the hulls. That suggests that the Base Speed is actually lower than shown.

 

Calvin H. Markwood
Engineering Analyst
Multihull Dynamics, Inc.

Contact Cal: multihull.analysis@comcast.net