We are a group of people passionate about diving, admiring this wonderful "World of the Silence". We try to develop our skills and gain in-depth knowledge. We often do quite long decompression diving in cold water, so we decided to get proper undersuits, which could provide us with suitable thermal comfort during diving in water between 3-4 degrees Celsius and will let us "survive" during decompression even when the suit is completely wet. As we were looking for the best solutions we found George Irvine's article (http://www.tue.org.uk/undersuits.htm), where he recommends to use DUI C-4 undersuit and explains why in his opinion this is the best undersuit and how it works. We learnt that DUI C-4 undersuit costs about 500 USD and is not easy to buy it. We discovered however that C-4 is made from Thinsulate 400, so we decided to buy this material and find someone to sew such undersuits in Poland.

We bought 30 meters of Thinsulate 200 and we began to seek a company, which would sew us a undersuit we wanted. It has not been easy, as Thisulate is thick and quite difficult at sewing. The first prototype was sewn by the company producing sportswear. This undersuit was very warm, but material used to finish the edges of thinsulate (polar 200) was too thick, so the undersuit was not very practical. It was difficult to put on the suit, we had to have heavier ballast and it was uncomfortable. This was not the good idea.

We phoned Tomek Stachura, the owner of the SANTI, the company, which had already some experience with sewing undersuits with Thinsulate 100 and 200. Tomek agreed to sew us undersuits using our material, according to the project we worked out together.

Our basic ideas were as follows:

1) the undersuit should fit the body very well to maximize thermal comfort given by gas trapped in Thinsulate fibers;

2) the outer layer must be made of the breathable fabric which remove sweat outside, and at the same time will protect the lining from moisture - we chose pertex - used among other things to sew sleeping-bags;

3) inside layers must be as thin as possible, so it does not limit movements - that is why the lining had to be thin too - it appeared that mikropolar 100 fitted best;

4) we needed additional elbow room, which would be gained by wide, elastic gussets, which should separate sleeves from the trunk and assure full freedom for hands, necessary eg. during turning the valves.

The SANTI company took action very professionally, and the final product was in fact the ideal undersuit. It lived up to all our expectations, and was simply nice and comfortable to wear, that you do not want to take it off after the diving.

An excellent test for the undersuit was 70 minutes long diving in water at a temperature 3O degrees Celcius, when I puropsely did not take the argon with me. During and after the diving I was still warm, what was a big surprise. Other members of our club were also diving in new undersuits even under ice and they had similar opinions. Now we know the difference between "I am not very cold" and "I am warm". I hope that with gained experience SANTI will start to produce this undersuit and all the divers will be able to feel the difference. :-)

We want to thank Tomek Stachura and SANTI for time spent, excellent work done and great patience during project realization.

Robert Klein

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