Sail Shape Help

Introduction

This program was initially written to assist in the design and layout of marblehead yachts.  It gives a visual display of the shape of the sail and a calculation of the sail area corresponding to the current rules for Marbleheads.  It creates a pair of sails (main and jib) and treats them together to enable the sail area to be calculated.  Any measurement factor may be varied on either sail to see the effect on the sail area remembering that the maximum allowed sail area for a Marblehead is 0.5161 square metres.  It calculates and displays the ratio of the sail area in the main and jib as percentages.  It automatically adds the 'free' roach measurements at the 1/4, 1/2 and 3/4 points on the sail.

When using the program for another yacht type the roach measurements used in Marbleheads are removed (though it leaves the 20 mm head width) resulting in a triangular plan form.  Additional roach measurements must be added manually to produce the required leech curve.  The resulting sail area calculation is only approximate but surprisingly accurate even for a Ten Rater where measurements are normally taken every 100 mm.  It is certainly accurate enough to get to the general shape and area.  Just leave a small excess along the leech to allow final fine adjustment using the appropriate rule.

The program is not useful for one metre sails where their dimension are already prescribed in their rules.

The program runs in Windows on any version of Microsoft Access after 2000.  The information about the program and information about the sail definitions are stored in separate databases allowing an update to the program to be made at a later stage without interfering with the sail definitions created.

The databases come with some examples of Marblehead and Ten Rater sails.  These can be deleted, copied or altered to suit.

While neither the program or data databases are in anyway locked, I would advise very strongly against attempting to change the structure or programming within the databases.  Instead contact me if there is an issue or a suggestion to improve the functionality

Contact Ben Morris

 

The following help items will assist understanding and using the program