Here's some dialog that I have had with my sail maker regarding their input on sail cloth weight for a high tech (string) main

Here's my first e-mail to the sail maker:
The requirement for a Dacron main is a sail cloth weight of 6.25 oz. What is the cloth weight of the Fusion X main that I bought? If I wanted to purchase a Fusion MT main; what is the recommended sail cloth weight of the Fusion MT (in other words, would it be different from the cloth weight of the Fusion X)?
Is there a minimum sail cloth weight you would suggest for a high tech, general purpose main? I appreciate your guidance

Their first response:
Most classes that allow some sort of high-tech sailcloth or sail construction do not use a minimum cloth weight, but rather a minimum finished sail weight. Something around 9-10 kg would work for a J30 main

Their follow up response:
This is an interesting question as I guess most OD classes recommend a bag weight. We looked up several resources and it looks like dpi would be in the 14000-15000 range. High tech string sails can be in the 12000 range. Your sail is a Flex 16, which equals 5.5 Sm Oz.

Not understanding what they told me I sent the following:
Thanks so much for the input. I apologize that I am, however not able to follow all the terminology.
Bag weight I think I understand = weigh the finished sail. I am not familiar with the other terms such as dpi and Sm OZ.
Backing up for a minute; current J/30 Class rules for the main read Minimum cloth weight is 6.25 oz.

The question then is, if the class allows non-Dacron sails what sail cloth weight should be used or if sail cloth weight is not appropriate what measure should be used (if any).
I saw the note that a J/30 main should come in at a finished weight of 9-10kg (I assume tht is bag weight). Can you be specific on weight; is it 9 or 10kg or something else? You have my sail at the loft, it's missing the battens but it could be weighed if you need a sail to weigh?

Next question. When I bought the sail, If I had upgraded to the more expensive Fusion MT alternative, would the Fusion MT sail have weighed the same or less?

To the forum;
I'll keep working on this. If anyone else has input from a sail maker on what wording to use for a high tech main sail weight please jump in here.

Last edited by Russ Atkinson; 03/09/11 05:57 PM.