People are naturally drawn to water, both for recreation and relaxation, and a house on the water is an almost universal desire. But building that house poses design and construction difficulties that few subdivisions can match. Site conditions are often problematic - rocky, hilly, sandy - and the house is constantly exposed to sun, wind, salt, sand, and storm. A suburban home can't withstand those challenges. So what will? In A House on the Water, Maine architect Robert Knight distills his year