How to Refuel a Boat Safely (Gas Dock, Gas Station and Portable Tanks)

Tie the boat to the fuel dock with bow and stern lines so it can't drift away from the nozzle. Then:

• Shut off all engines.
• Turn off electronics, the stove, heaters and anything else that could make a spark or flame. That includes a running generator.
• No smoking anywhere near the dock.

BoatUS and Discover Boating both suggest having everyone who isn't fueling step onto the dock. It keeps them out of harm's way if something goes wrong, and it means no one is moving around or switching things on while vapor is present.

Close every port, hatch, window and cabin door before fueling. This stops vapor drifting from the fill into the cabin and bilge. (After fueling you will do the opposite.)

Treat fueling as a job that needs both hands and full attention. Put your phone in your pocket, and lay an oil-only absorbent pad (or a fuel collar) around the deck fill to catch drips. Keep the fire extinguisher where you can reach it.

Open the correct fill cap and insert the nozzle. Keep the metal nozzle touching the edge of the fill the whole time. BoatUS explains this keeps static electricity from building up and sparking. Hold the nozzle yourself with a firm grip: BoatUS says never use the hands-free clip on the pump handle.

Boat tanks are vented to the outside of the hull. If you fill to the top, fuel comes out the vent fitting and runs down the hull into the water; BoatUS's spill guide describes exactly this happening at a busy fuel dock. Fuel also expands as it warms, so a tank topped off in the cool morning can push fuel out the vent in the afternoon sun. BoatUS puts a number on it: fuel pumped from a cool underground tank can expand by as much as 10 percent once it heats up in a boat or portable tank.

Marina pumps don't always shut off by themselves the way car-station nozzles do. MasterCraft's fueling advice is simply never to leave the fill unattended, and to make sure a snap-shut fill cap clicks fully closed when you're done.

• Slow the flow as you get close to full.
• Listen and watch: a change in the sound at the fill or a gurgle means you are nearly there.
• Stop at about 90 percent of tank capacity, as BoatUS recommends.

Close the fill cap tightly. Wipe any fuel on deck or around the fill with an absorbent pad. If fuel dribbled out of the vent, wipe the hull too. Put used pads in the fuel dock's container for oily waste, not loose in the trash or the water.

Now open all ports, hatches and doors so fresh air can move through the boat. On boats with an engine compartment, open the engine hatch if you can.

Turn on the bilge blower and let it run at least four minutes before starting the engine, per the BoatUS checklist. The blower pulls vapor from the low spots that natural airflow can't reach. Leave it running while you start the engine.

The four-minute rule isn't just advice: federal boatbuilding rules require gas-inboard and sterndrive boats with a blower to carry a warning label near the ignition switch telling the operator to run the blower for 4 minutes and check the engine compartment bilge for vapor before starting. If that label is missing or faded on your boat, replace it so guests and new operators see it. Listen for the blower and feel for airflow at the vent outlet; a blower that hums but moves no air (crushed hose, clogged intake) is not protecting you.

Before you touch the key, put your nose in the engine compartment, the bilge and near the blower outlet. If you smell gasoline:

• Do not start the engine. Do not operate any switches.
• Keep ventilating, look for the source (a loose fill hose, a leaking fitting, a soaked bilge), and get help from the fuel dock or a marine mechanic.
• A raw-fuel smell that doesn't fade is a leak, not "just fumes."

Only when the boat smells clean do you start the engine, bring passengers back aboard and cast off.

For boats with portable tanks, BoatUS says to take tanks of six gallons or smaller out of the boat to fill them. The same goes for gas cans:

• Set the tank on the dock or the pavement, never in the boat, a truck bed or a car trunk. A tank sitting on a plastic bedliner or a boat deck can build static charge. BoatUS adds a habit worth copying: touch something metal as you get out of the vehicle, before you handle the nozzle, to drain off static you picked up from the seat.
• Put an absorbent pad under it and keep the nozzle in contact with the tank opening.
• If you premix for a two-stroke outboard, add the oil your manual specifies.
• Close the cap and vent, then strap the tank down in the boat so it can't slide around.

Many trailer boats fill up at a roadside station, where gasoline may be cheaper but ethanol content varies. BoatUS suggests leveling the boat (adjusting the hitch height if needed) so fuel goes in more easily and is less likely to spill, and standing where you can see the deck fill and hold the nozzle comfortably, even if that means a step stool. Check that the pump is not E15 or E85.

PWCs have small fills and short distances to the water, so drips land in the lake quickly. Tie up to a stable dock, fill slowly with a pad around the fill, and stop short of full. Before starting, open up the engine compartment:

• Sea-Doo suggests removing the seat to let any fumes that built up in the engine compartment escape.
• Yamaha's pre-launch checklist says to remove the seats and storage compartments and leave the compartment open for a few minutes, then check the fuel system for leaks by looking and sniffing.

Yamaha also suggests the "thirds" rule: one third of your fuel to go out, one third to come back, one third in reserve.

Spills happen even to careful boaters. BoatUS explains the rules:

• Federal law prohibits discharging fuel or oil into the water. Any spill that leaves a sheen must be reported to the National Response Center at 1-800-424-8802.
• Stop the source, use oil-only absorbent pads or a boom, and tell the marina.
• Never use dish soap or any detergent on a sheen. It is illegal and it makes the fuel sink, where it does more harm.