Staying warm is very important especially in cold water. When dinghy sailing most of the time you do not get too wet, unless you trolley your boat into the water, then your feet can get very cold and if you happen to capsize you want to reduce "cold water shock" as much as you can. The "Gul Power 4mm wetsuit socks" are one of the best you can buy at a very good price. But with a set of wetsuit boots they work even better. "Gul CZ Windward 5mm Round Toe Boot 2014" or "Crewsaver Zircon Sailing Boots"