Just got more input from my sailmaker. Look to my 03-09-11 post if you want to follow this dialog from the beginning
From the sailmaker:
Here is a bit more info that hopefully will help you and the class make progress towards the proposed changes in mainsail material.
Sm. Oz. is just an abbreviation for sailmaker's ounces, the generally accepted measure of the weight of cloth in the sailmaking industry.
"dpi" stands for denier per inch. With dpi, you are measuring how much fiber is in a given cloth or a specific sail. High-tech "string" sails (Fusion M, 3DL, D4, Tape-Drive, etc.) are generally referred to as having a certain dpi. For example, North Sails offers a J 105 class jib with 16800 dpi, that meets the class minimum finished sail weight of 23.8 pounds. The problem with dpi, with regard to string sails, is (unlike cloth weight) there is no standard throughout the industry on how exactly dpi is measured. So, jibs from 3 sailmakers for the same boat, each one at say 15000 dpi, could all be quite different in finished weight.
Your last main was built with cloth that has an overall dpi content of approx 16000.
Your last main weighs approx 29 pounds (13kg). If it had been a Fusion M main, it would have certainly weighed less. The 9-10kg number is an estimate for a J30 main, based on comparing the minimum mainsail weights in several other classes, and obviously taking area into account - Rick
To the class... any thoughts on how to deal with this? Perhaps a minimum DPI and a minimum bag weight?