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Gary Hendrickson (Garyh)

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Posted on Friday, March 01, 2002 - 09:23 pm:   

2001 9.1 Keel Investigation Summary

Adopted by Resolution at Annual Class Meeting Feb. 2, 2002

Prepared by Gary Hendrickson (#094), Class Rules Committee


The goals of this investigation were:
1. Validate the specification drawing for the 9.1 keel.

2. Try to get an idea how well keels as-built by S2 conform to that drawing.

3. Determine if the commercial CompuKeels keel template set for the 9.1 conforms to 9.1 drawing specifications

1) Scott Graham of Graham & Schlageter Naval Architects, designers of the 9.1, confirmed to me that the drawing I have was the one used by S2’s vendors to build 9.1 keels. In addition, measurements we made on several 9.1 keels all agreed with the basic proportions & dimensions required by this G & S drawing.

2) A keel measurement project on 9 boats with hull numbers between 002 and 094 (out of 128 built) showed that their keels all complied closely to the dimensions and proportions called for on the G & S keel drawing. This held true for both the earlier keels supplied by the original vendor using the two-half molding method and for the later-keels vendor who used a sand mold for the keel. (The shoal-draft keel was not considered)

The measurement system we used collected 12 or more thickness measurements from each keel. The measurement points were located at 20%, 40%, 60% and 80% along each of three section chords. These sections were positioned near the top of the keel, at its mid-point, and near the keel’s bottom.

3) A comparison of dimensions and foil shape of the 5-section keel template set offered for the 9.1 by Computer Keels of Edina, Minnesota with the G & S keel drawing showed very good agreement between the two. This comparison was done by a) carefully extrapolating the G & S keel dimension specifications to the 5 locations on the keel that correspond to the 5 positions for the CompuKeels templates, b) measuring thicknesses along each of the 5 templates, and c) comparing the template thickness measurements to the G & S thickness requirements for each of these 5 locations.

Conclusions:

A. Graham & Schlageter Naval Architects Inc. Drawing No. 035-09A Sheet 1 of 4, 9.1 Keel Sections etc., is the document that defines the shape & dimensional design of the S2 9.1 Meter keel.

B. The drawing’s dimensions for the 60 inch Root Chord and the Tip Chord (separated by 48” top to bottom) can be proportionally extrapolated to any other section location on the keel, for the purpose of determining if a 9.1 keel complies with Class Designs.

C. The keel template set for the S2 9.1 Meter offered by Computer Keels as of April 2000 have been found to conform to the G & S keel drawing.

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