The purpose of this research is to carry out the quantitative estimation of the thermal insulation properties of some inner clothes of the wet suit. Four different samples of the inner cloth used for this experiment are selected among the recent typical products in the wet suits market. The first one of the samples is made of the hollow fiber which contains large volume of air, and is one of the most popular materials for the warm wet suits. The second is a very thin plain knit of one layer. The third is coated with the titanium powder for the smooth surface. The fourth is permeated with the fibroin to produce the minus ion. The evaluation was done by using time-constant theory based on Newton's Cooling law. The hollow fiber is effective on the improvement of thermal insulation property for the inner cloth under the condition which doesn't contain water. Thermal insulation property of each wet suit containing water warmed up by the body heat is almost same as the one under the condition which doesn't contain water. When water flows into and out of the wet suit through such openings as a neck or other end parts, the inner cloth with good drainage property is effective on the improvement of thermal insulation property.

DESCENTE SPORTS SCIENCE Vol.26/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE