When we left the dock for what we knew would be a long day of 470 racing the weather was just about as good as we could expect from Kiel, Germany, in early June. It was about 60 degrees and only partly cloudy with about 15 knots of breeze. About six hours later, as the race committee got ready to start the third race of the day, a large black cloud started to block the sun. As the wind increased and the conditions began looking potentially dangerous, the race committee called it quits for the day. It wasn't a bad idea but we were a two-hour beat away from shore. The temperature dropped rapidly and then the hail started to come down hitting my face at an apparent speed of about 25 knots, only interrupted by the cold North Sea water soaking my body. I was unprepared, underdressed, and shaking before we were even half way home. Needless to say we were freezing when we got in. I'd had cold days on the water before but that day at Kiel Week was the final straw. From then on dressing appropriately became an important part of my pre-sailing routine.
The most significant of these developments has been the evolution of the dry-suit. First introduced to the sailing scene in the early '80s the dry-suit allows sailors to stay dry and warm, even after falling into the water. Sailing your Laser all winter all of a sudden became a real possibility. By coupling a good dry-`suit with high-tech synthetic fabrics, cold weather sailing can almost become comfortable.
Choosing the right clothing for you will depend on the temperature and what type of sailing you're doing but the basic principles of staying warm will remain the same. Here are some of the things I've learned sailing dinghies.
When dressing for cold weather your clothing should be broken down into three layers. The first layer, closest to your skin, should move moisture away from your body. The middle layer is a thermal layer that will keep you warm. These two layers are protected from the elements by an outer layer that blocks wind and water.
|"If this moisture is held against your skin it will work to cool your body. Water is good at transferring heat. If your skin is wet it will cool up to 25 times faster than if it was dry."|
No matter how cold it is, your body is constantly expelling water from the surface of your skin. This moisture usually evaporates immediately but when you are bundled up under multiple layers of gear the moisture can build up and condense. If this moisture is held against your skin it will work to cool your body. Water is good at transferring heat. If your skin is wet it will cool up to 25 times faster than if it was dry. Your first layer of clothing should therefore pull this moisture away from the skin. Materials like polypropylene and polyester that tend to resist water retention work best. Although cotton may be comfortable when it's dry, it is one of the worst materials for staying warm on the water. Cotton will retain a high level of moisture and hold it against your skin, rapidly moving heat away from your body.
The middle layer is what will actually keep you warm. You should adjust this layer to match the temperature. This layer will trap warm air and insulate your body. Air is not good at conducting heat and is therefore a good insulator. A good middle layer will also continue to move moisture away from your skin. Fleece and wool are both good insulators. Dressing with multiple middle layers will allow you to easily adjust to a change in temperature.
When sailing in truly cold weather, like New England in December, a dry-suit is a must for safety and comfort. There are two basic types of dry-suits available: breathable and non-breathable. The type of suit for you will depend on how long you spend on the water. A breathable suit allows moisture from your body to evaporate through it while still blocking wind and water from the outside. This will inhibit the buildup of moisture and even sweat, keeping you dryer and warmer. If you are potentially going to be out on the water for more than three hours at a time, a breathable suit is preferable. If you're only going to be out for a few hours at a time a less expensive, non-breathable suit is fine. With a non-breathable suit ,moisture from your body will condense on the inside of the suit but as long as your skin stays dry, thanks to good layering, you will remain warm and comfortable.
On cold days the real limiting factors are your hands and feet. Most dry-suits are available with rubber booties attached. Booties will keep your feet dry even if you have to walk into the water to launch your boat. Here's a trick. If your dry suit doesn't have booties get a pair of replacement booties and tuck them into your ankle seal. It won't be a perfect seal but it works surprisingly well. Rubber booties and boots will keep your feet dry but they will not keep them warm. Rubber is not a good insulator so you must rely on good socks. Unfortunately the available space in your sailing boots will most likely prevent you from layering. If your feet are too tight in your boots the circulation will be inhibited, slowing the flow of warm blood and making your feet cold. Having a slightly larger pair of boots for winter sailing is not a bad idea. Polypropylene, fleece, and wool socks are all good insulators.
It goes without saying that you should never go out on a cold day without a good winter hat. A good hat will have all the properties that have been explained. It will block the wind and it will not retain high levels of moisture. As a test, the fastest drying hat is the one that retains the lowest amount of moisture.
Finally, get dressed in a warm place. Good gear only traps the heat that your body has already produced. You can't expect to wrap a steel pole in fleece and warm it up. If you wait until you're cold your gear will be much less effective.
The Science of Keeping Warm
Dressing to stay warm is all about slowing the transfer of heat from your body to the outside environment. Basically you're trying to put your warm body in the best thermos possible. The process of heat transfer can be described quantitatively using the law of heat conduction: H=kAdT/dx.
In the equation above, H is the amount of heat energy per unit time that moves from your body to the outside. A is the surface area of your body. dT is the difference in temperature between your body and the outside. And dx is the distance from your skin to the outside. The final element, k* is a constant determined by the insulating material.
The k, or thermal conductivity, of water is .6. The thermal conductivity of air is .023. From this you can see that the conductivity of heat through water is (.6/.023 times) or about 26 times greater than through air.
Dry fleece is mostly trapped air and has a thermal conductivity of about .08. Cotton saturated in water is mostly water and will have a thermal conductivity close to that of water. The thermal conductivity of rubber is .2. It's pretty easy to see that dry fleece is the way to go to maintain your body heat.
Last edited by administrator; 02-05-2008 at 09:28 AM.
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