Keep your trash to yourself. Limit the amount of packaging material you take aboard, whether it's for tools or food, by stripping off wrappers and other excess while on land. Bring food aboard in reusable containers rather than disposable plastic bags, and take the containers home. Equip your boat with a sturdy trash container with a lid. Stow all loose items, plastic containers and beverage cans properly so they don't blow overboard, and don't let your crew members or guests toss anything into the water. If trash does fall overboard, retrieve it. The Coast Guard sums it up well in its list of tips: "Whatever you take aboard, bring back."

Don't go overboard. Federal law prohibits you from discharging any garbage into lakes, rivers, bays, sounds or coastal waters up to three miles offshore. You may not dump plastic, packing materials or most other trash anywhere from three to 12 miles offshore, and it's illegal to throw plastic over the side in any waters. (If your boat is 26 feet long or larger, you must display this information in a placard, available at most boating supply stores.)

GLEN JUSTICEWhatever is in your bilge goes into the water when you pump it out. If you see a sheen, stop. It is illegal to dump oil, fuel or other chemicals in U.S. waters. GLEN JUSTICE

Recycle. There is much aboard a boat that can be recycled. The obvious items are glass bottles, plastic packages and metal cans. Not-so-obvious items include sacrificial anodes – the zincs – that are replaced seasonally, and the shrink wrap used during winterization. Batteries too can be recycled, as can oil and antifreeze.

SEWAGE AND FUEL

Be tidy about maintenance. When doing bottom work, collect all paint chips and other residue and dispose of it in designated trash cans ashore. Consider using one of the new, lower-toxicity antifouling paints to protect your bottom. Ordinary bottom paints often contain copper, mercury, arsenic or tributyltin, which harm the underwater ecosystem. The new generation of low-copper bottom paints have received good reviews from boating magazines. The October 2007 issue of Practical Sailor has a report on bottom paint.

Mind your sewage! Ask your crew to use restrooms ashore before coming aboard. Make sure your head is a Coast-Guard-approved model, and that it is in working order before you leave port. Show your guests how to use a marine head and tell them to call you if they forget the instructions. Never discharge raw sewage in U.S. territorial waters – it's a violation of federal law.

If you have a holding tank, be sure your Y-valve is locked in position to prevel illegal discharges (the Coast Guard will ding yo if it isn't). Pump and rinse out your holding tank regularly at a pumping station. Many fuel docks provide this service free when you fill up, and marinas often offer regular service for a small fee. Take care not to spill anything during the process. If you do cause a spill, wipe it up promptly using oil-absorbent pads. Use enzyme-based products to help stifle odors. Avoid head-maintenance products that contain quaternary ammonium compounds and formaldehyde.

Fuel carefully. Before you begin fueling, spread oil-absorbent pads around your intake. Because fuel tanks on boats aren't pressurized, they frequently belch fuel out of the intake without warning. If your boat is on a trailer, fill its gasoline tanks while it is on land, rather than when it is in the water. Fuel carefully to avoid spilling fuel or overfilling your tank. Don't let anything distract you. You can buy a new inline fuel-air separator, also known as a vented fill, for between $20 and $140 that will minimize the danger of overfilling. For safety's sake, have someone call out the number of gallons you take in while you're fueling.

Don't try to top off. Leave a 10 percent gap so fuel doesn't overflow. If you do spill fuel onto your boat or the pier, wipe it up with a rag – don't wash it into the water. If you spill fuel or oil into the water, don't try to disperse it with detergent or soap. That only sends it to the bottom, where it's more difficult to clean out. If the spill is large, you must report it to the Coast Guard's National Response Center at 1-800-424-8802 or via VHF radio. Failing to do so could cost you fines and penalties.

Be especially mindful of the bilge, where oil, fuel, antifreeze and other chemicals can collect. To avoid leaks, inspect fuel lines and hoses frequently, replace those that are worn and secure them properly. Never discharge bilge water that has a sheen.

GOOD HABITS

Motor slowly. How you use the boat also matters. Proceed slowly in shallow waters so as not to disturb fish or wildlife. Avoid plowing through underwater vegetation. Watch your wake: Not only can it cause injuries or damage, but it also can exacerbate erosion of the shoreline. If you run aground, don't gun the engine to try to get free. Not only can that damage your engine and propellers, but it also could hurt the sea floor and marine organisms. If you sight a marine mammal such as a dolphin, manatee or whale, slow down and keep at least 100 yards away. It's illegal to feed, harass or injure a marine mammal.