To fellow TC members, i have been contacted by Rafal Sielicki P-254 Commodore of Polish DN Fleet with the following letter;
Hope you are well.
As a Commodore and active competitor of DN class I want to share with you my thoughts about Karol Jablonski sail cloth proposal.
First of all the DN class rules should be clear with no room for overinterpretation.
I know that TC is working on that already so I think that’s good time for clarify sailcloth specification too.
Today’s specification is :
- The cloth must be made with high tenacity polyester (dacron) yarns. Sail cloth
must be made with either of the following cloth constructions: 6.5 oz. cloth
with 220 denier warp and 440 denier fill yarns or 280 grams/square meter
cloth with 250 denier warp and 410 denier fill yarns.
1.Sail ( interpretations)
1977: It is not legal to use two ply Dacron 6.5 oz cloth for the top panel and bottom
panels for reinforcement.
9/1/99: It is legal to use Contender 6.5 oz. Polycote cloth in the construction of the sail.
Which means we have two sailcloth suppliers with different weight ( 6,5oz is not exactly 280grams) and also different arrangement in denier warp and fill ( Contender 200x 440, Polyant 250 x 410). These are not the same products, but I’m completely sure that this difference has no any advantages or disadvantages to one of them – just look at the results of top sailors using both types of cloth.
That’s why I agree with Karol that to keep denier warp and fill in the sailcloth specification is pointless. Moreover all producers in the world doesn’t matter if they produce sailcloth, textiles or other materials they produce with specified accuracy, which means that there can be and for sure there is batch to batch difference in weight as well as denier warp and fill, which means that two sails made from different batches of sailcloth are not the same, but again it has no effect on the sail performance at all.
As long as the grammage of sailcloth can be measured in workshop conditions, then to measure weft and warp is impossible.
Another think comes to my mind: what if somebody will find new sailcloth (e.g. in China)
which will be cheaper but with slightly difference in construction or weight – 275grams for instance, from DN class point of view this is good to have cheaper equipment which allows to acquire new sailors, but this type of sailcloth is illegal due to class rules.
Summarizing: we should get rid out of denier warp and fill and specify the tolerance +/- 5 or 10%. And in my opinion TC could decide that change directly without the ballot, because most of the people are not aware of that issue at all.
As I know following topic was added immediately to class rule without ballot :
9/1/99: It is legal to use Contender 6.5 oz. Polycote cloth in the construction of the sail
Jeff as a Chairperson of Technical Committee how do you see the way to implement these changes? In my humble opinion it should be done asap, that in coming season everything will be legal.
Waiting for your reply.
Commodore of Polish DN Fleet
As TC chair i acknowledge that out specification can be confusing but at the same taime ove r the decades the sailmaker have done a good job working with them. to my understanding the materials do change from roll to roll and selective inspection has been done to get best quality fabric to meet their requirement’s. the rolls still met the class specification within the specific allowed denier counts but the sailmaker might not liked the quality or some other aspect of a specific roll of product.
In my opinion the class does not have a real big issue here to deal with. some sailmakers are requesting to open the specifications to say a specified areal weight cloth only similar to what we use currently, However no warp and fill counts. Specified. this will open sail material to many variants on 6.5 oz cloth . Currently the ones we specify are nearly a balanced weave warp x fill with their suggestions a warp oriented cloth could be used satisfying the 6.5 oz requirement but it is a totally different material. with these material full radial designed sails would be legal. honestly not sure if they would be be better or not that would be for the sailmakers to persuade us the sailors.
Again my opinion, they would look cool as compared to our simple crosscut sails , possible could have better control to get a better designed shape. . I do believe they will be more costly though as they are considerably more seam etc..
being on the board i ask you to read the above letter and consider what direction the TC should go on this.
the class may be be calling for this change . so far I have only heard it from a very few.
I look forward to you responses
jk TC chair