Sailing in a wet suit in cold weather is not very comfortable. In fact, sailing in a wetsuit in any weather is not very comfortable. If it's too cold for shorts and a spray top, wear a breathable dry suit (don't cheap out here; get breathable or don't bother). Your range of motion is unrestricted - unlike wetsuits - you can add layers if the water gets really cold and if you capsize, you stay warm in the water and after you get back on the boat. You can't imagine how comfortable a drysuit is until you've tried one, but once you do, you'll never go back.