If you’ve done a thorough job winterizing your boat in the fall then your spring pre-launch prep isn’t so bad. You’ll want to replace and test your electronics, and wash and wax the hull. Aluminum boats or those stored in the water in a slip or on a mooring ball need bottom paint. Scrape and sand the bottom, and apply the anti-fouling paint as air temperatures dictate. Charge and install your battery, add fresh gas, and check your navigational and trailer lights. Cold weather and rubber don’t always mix, and fuel lines and tires may be worse for the wear. Look for cracks and replace as necessary.
If you’ve serviced your engine in the fall then water pumps, thermostats, oil and gas filters, and fluid levels are good to go. Nonetheless, check them out and top off as needed. Similarly your prop and lower unit oil will be fine. Larger boats with bilge pumps should be reviewed for functionality, with the circuit, the pump and the automatic switch being the most important.
Cold weather shrinks caulk, so lay a fresh bead around decks, casting platforms, or wherever necessary. Grease also shrinks, so repack wheel bearings. While you’re under the trailer check leaf springs and brackets. They can rust during seasonal storage.
Add your safe boating gear, with one life jacket per boater, a throw cushion, a fire extinguisher, anchor, line, whistle, flare, and mirror. Add GPS, cell phone, clothing, food and water for emergency, too.