To prepare your boat for the water, follow these tips-and refer to your owner's manual for specific maintenance instructions.
Change the engine oil and spark plugs.
Many boat manufacturers recommend that you change the engine oil in the spring, because during storage, the oil can separate, causing condensation to build up — potentially harming your engine. While you're changing the oil, replace the spark plugs and set the gaps according to the manufacturer's recommendations.
Prepare the outdrive.
Check or change the oil in the gear housing, inspect the seals for signs of deterioration, check the power steering oil level and grease the entire drive.
Check the battery.
Clean the cables and terminals with a wire brush and reconnect them. Fill the cells with distilled water, if necessary.
Flush the cooling system.
Flush out any antifreeze from your system and replace it with a proper coolant. Replace any cracked hoses, too.
Check the fuel system.
Replace the fuel filter and examine the fuel lines for cracks. Make sure the lines are connected and supported with approved clips and straps. Also inspect fuel tanks and pumps for leaks.
Perform other basic maintenance.
Check the belts for signs of wear and tear. Inspect the bilge pump, adjust the steering cables and check all navigational equipment.
Prepare the trailer, if you have one.
Check the tires — including your spare — for cracks, worn treads and correct tire pressure. Check and grease the hubs, and test the backup and taillights. If necessary, replace any burnt-out bulbs or cracked wires. You also may want to operate the winch to be sure it is working properly.
Prepare safety equipment.
Inspect personal floatation devices, check the expiration dates on fire extinguishers, replace old flares, test the radio and sound all warning horns.
Be sure you're covered.
Review your boat insurance policy to make sure it fits your current needs. If you've added any equipment to your boat, for example, you might need to buy more coverage. Also, make sure you know how to report a claim.