If you don't have a slip or dock where you permanently store your boat, you need to ensure you're protecting that boat while it's on a trailer and in transit. This includes keeping the trailer in good condition and knowing all the accessories needed for proper handling of the boat itself, especially when you're loading and unloading it. Note a few tips for maintaining that trailer so you're protecting your boat while hauling it, and this will ensure you enjoy years of fun sailing while also avoiding unnecessary boat repair bills.
Check the tyres
The tyres of the boat trailer are vitally important for the safety of the boat itself; never assume that you can or should use cheap tyres or mismatched tyres for the trailer, as this can allow them to skid and slide against the weight of the boat. It's also good to check the alignment of those tyres regularly, perhaps even more often than you check the alignment of your vehicle's tyres, as poorly aligned trailer tyres can also mean skidding and sliding. This increases the risk of allowing the trailer to flip when you hit the brakes or take a sharp turn.
Coat the springs
A boat trailer will have springs under the wheel well, just like a car, to absorb impact and keep the boat itself from slamming up and down when you hit bumps. Water can drip from the boat onto these springs, and they can also get wet and coated with refuse from the water when you back the trailer into the lake or ocean to load and unload the boat. This water, and especially saltwater, can easily cause those springs to rust. Coat them every year or as often as needed with a protective lubricant that will keep them from rusting and that will ensure they're always in good working order.
Maintain the rollers
Boat trailers will have boat rollers, or wide and rounded pieces that allow the boat to easily slide on or off the trailer without scraping the bottom. As with springs, those rollers can suffer rust and corrosion from being exposed to water, and especially saltwater. Check these rollers often to ensure they move easily, and spray them with lubricant as needed. Note if the surface of the rollers is chipped or cracked; if so, the rollers need replacing. If you maintain those rollers properly, the boat won't suffer scrapes and scratches when being loaded and unloaded, and this work will also be easier on you.