Since our float cabin doesn't have any flat land, when Wayne and I aren't riding our quads they stay parked on our barge.
When we get back from a dirty ride, Wayne hooks up the garden hose to our Hewscraft Ocean Pro's deck rinsing system and gives the bikes a good washing. Fortunately, we live on a fresh water lake.
Then, to protect the quads from the elements (sun, rain, snow depending on the season) we purchased a set of QB (Quad Boss) ATV Quad Covers. We chose black, but they also come in woodlands camouflage. The XL size completely covers our Yamaha 450s from top to bottom. They also come in 2XL for larger quads. The cloth is water-repellent and UV resistant. Elastic hems tuck the edges in to keep them from blowing off, but to be extra sure we use several long bungees to make them ultra secure for our windy winter weather.
UPDATE: Well, they worked great for one year and three months, but being outdoors 24/7 took it's toll. I would still give them a good recommendation as long as you know that constant use in sun, rain, wind, and snow can shorten their lifespan. (December 30, 2015) -- Margy