Effects of water temperature on performance: a practical evaluation of a neutral buoyancy facility

Manual and cognitive performance of two female and four male divers was evaluated in "cold" and "warm" water in a Neutral Buoyancy Facility (NBF). A test battery of six manual and cognitive tests was applied in a fixed sequence in three separate, 3-h dives: Dive 1) Water temp.: 18-19 degrees C, wet suit 3-5 mm thick; Dive 2) Water temp.: 32-33 degrees C bathing suit and T-shirt; and Dive 3) Water temp.: 18-19 degrees C, tailor made wet suit 6.5 mm thick. No significant differences in performance between the three conditions were recorded. Mean rectal temperatures decreased by 1 degree C in all dive conditions, except in females in Dive 2. Ventilation was significantly higher in Dive 1 than in Dives 2 and 3. Thermal discomfort was reported only after 2 h in Dive 1. We suggest that support divers may work safely, comfortably and effectively for at least 2 h in water of 18-19 degrees C, if dressed in thermal protective wet suits.