Originally Posted by crazychemical
forcast says between 3°C and 6°, with watertemps at around 10°. How long do you guys stay in the water at these temps?
It largely depends on a number of variables, but research has shown that the predicted 50% survival times for fully clothed men in water wearing lifejackets are 1 hour at 5°C, 2 hours at 10°C, and 6 hours at 15°C.
However, since windsurfing is done most of the time in air and water spray and not fully immersed in water (except for the few waterstart or unavoidable falls), the most critical variable I've found so far is the wind chill factor for my fingers resistance to cold. Even 10-11 °C water is no problem going barefoot, but cold air + wind is a real killer in the long run. After 2-3 hours, my fingers are usually becoming numb enough that it's about time to give up. I'm wearing a neoprene 5/3 mm drysuit, 2 mm neoprene full hood, 3 mm booties, 3 layers of latex examination gloves or 2 layers of dishwashing gloves (made waterproof by taping with duct tape to the drysuit's wrist/forearm), helmet and a snug life jacket (it does keep you warm as a true wind stopper). As soon as fingers get wet from sweating, they get numb and cold and the game is over just before it hurts (frostbite).
The problem with a steamer is the cold water shock when falling into water for the first time, especially when cold water sneaks into the warm neoprene suit near your vital organs (heart and kidneys). It's a good idea to wear a neoprene shorty underneath your steamer, but not a lycra because when wet, you start to get cold. Unlike the neoprene shorty, lycra is a water sponge with zero insulation power when fully soaked. Wet lycra feels a lot colder on your skin than no lycra at all.
Finally, as Ola has pointed above, safety first: wear a helmet & a life jacket/PFD, know your own limits and plan some "safe harbour" exit strategies if things go unexpectedly wrong...