First of all, English is not my native language, excuse me for all the grammar mistakes I will make.
At the same temperature, water feels cooler than air. This is explained here. I know the temperature we feel is highly related to the rate of heat loss of our body. At water, we lose heat faster, and that's why it feels cooler. Knowing that, I wanted to calculate at which temperature the air has to be to feel the same as water at 11ºC. To do so, I need to calculate the rate of heat loss of our body in water at 11ºC.
How can I calculate it?
The person is completely naked and submerged into the water. His temperature is 37ºC. He does not move in the water. The water flowing past the person is moving at a V speed, for example 10m/s.