Nobody likes to make repairs to their boat during the boating season, and if you maintain your boat, you may not have too. There will be times when things come up that need to be dealt with right away but if it can wait. There are a lot of things that can only be done in the offseason while the boat is out of the water and some that can be done with it still in the water. In either case, neglecting the needed work on the vessel may leave you stranded, and that is the last thing you need or want.
Getting your boat out of the water allows you the time to get under the hull and clear it properly. If you boat in salt water, barnacles, and other organic matter can attach to the boat's hull, and over time the build-up can cause damage. If it is not removed, it can add weight to the bot as well as causing the boat to lose the shape that allows it to cut so cleanly through the water. The time spent cleaning the boat is necessary if you want to repaint it as well.
Painting - in and out of the water
Painting your boat is another offseason activity that is easier out of the water. The boat can be painted above the water line in the water, but care must be taken to ensure no paint gets in the water. If you are taking the boat out for the winter, try to plan your cleaning and painting time to correspond with the time that the boat is in storage. If you are painting, make sure you use a good quality marine paint to ensure the job will last. If the boat is a fiberglass boat, the gel coat used on the boat is pretty resistant to color fade or any real damage that would require painting, but it should still be cleaned while you have the opportunity.
Engine and drivetrain Maintenance
On boats with inboard or inboard/outboard motors, the best time to work on them is while the boat is out of the water. On the I/O (or inboard/outboard) design, the motor is in the boat's hull, and the lower unit is attached to the outside in the rear of the boat. That lower unit has oil in it that lubricates the gears and bearings, and it should be changed at the end of the season. The lower unit can get water inside it so changing the oil and drain the case completely will also remove the water from the inside. While it is not required to take the boat out of the water to work on the inboard motor, it is easier to do.
Contact a boat repair service for more information and assistance.