Design # 98; SHEERNESS (KATABATIC)

Built by: Mark Lindsay/Boston Boatworks, East Boston, MA

Launched: 1998

DESIGN #98: 43.7 ft LOA Grand Prix ‘IMS’ Racer 11/20/97

VERY Preliminary Specifications:

LOA 43.7 ft                                                       Sail Area (RSAT) 1,076 ft^2

LWL 37.7 ft                                                      ‘IM’ 52.0 ft

Max Beam 12.6 ft                                            ‘J’ 16.0 ft

Draft 8.9 ft                                                      ‘P’ 55.2 ft

Disp (Meas Trim) 13,750 lbs                           ‘E’ 20.1 ft

Ballast 8,800 lbs                                             Est IMS “GP” (‘97) 556sec/mi

RMC 1,555 ft-lbs                                             Implied PHRF 0 sec/mi

Equipment:

Spar: Carbon 3-spreader fractional w/jumpers;

Rigging: Discontinuous rod

Winches: Lewmar, 2 each; Primaries, Mainsheet, Spin Sheet/Halyards & Runners

Electronics: Ockam

Engine: 34 hp Yanmar Diesel w/sail drive

Construction Details:

The Hull consists of KEVLAR and ‘S-Glass’ composite skins over CORECELL SAN foam cores whose density is varied to suit local loadings. The deck is a similar laminate of FRP skins over CORECELL foam, with high compression core and additional laminate in way of all deck hardware. Gougeon epoxy resins are used throughout. Both hull and deck are locally reinforced with unidirectional KEVLAR to minimize the longitudinal deflections resulting from the headstay, running backstay and mast compression loadings. Methodical weight control is a high priority, and all moldings and components are carefully weighed before assembly.

Design Comments:

• Targeted to rate 556 GPH, just above the “bubble” of current 39-43 footers, e.g. Farr 40OD (560), ILC 40’s (565), Raven (557.5), Tripp 41 (562), N/M 1200 (572) and Farr 39ML (564). This target rating would also be safely slower than the small end of the big class in high-level events that split their IMS fleet into two divisions. It is always a huge advantage on the big, fast side of the class.
• Optimized for both very light air on the one hand, and a solid breeze with a big chop on the other, when compared to our medium air winners NUMBERS and SCHERHERAZADE. This results in less displacement for the sailing length, and more sail area for the displacement.
• Optimized to 1998 IMS rule, with a special eye towards the impact of changes in windage assessments. Both mast sizes and freeboard can go back to more reasonable and attractive values.
• Features a fully adjustable “racing rig,” as opposed to the swept-spreader ‘one-design’ rigs that are simple in concept, but have proved to be very complex on the race course. This design will reliably control these ‘simple rig’ boats upwind, and will also match them more closely downwind than our previous IMS racers. Several significant refinements have been incorporated in the rig details based on our recent research and Admiral’s Cup and America’s Cup experiences.
• Similar overall hull parameters as SCHERHERAZADE and NUMBERS, i.e. long effective sailing length for the rating, narrow waterline beam, generous area foils, and ample stability.