Most boat owners take a more hands-on approach to the upkeep of their vessels by performing some of the work themselves. The key to successful DIY boat maintenance is having the right tools and taking the time to learn what to do and how to do it correctly. 
The average boat engine requires oil changes on a regular basis. However, the type of boat, boat size, and frequency of use will determine how often the engine needs to be serviced. Most manufacturers will provide specific maintenance guidelines for the boat model and engine type.
Another basic boat maintenance service is to inspect the propeller for dents and corrosion. The propeller is an important part of your vessel, and even small dents can cause it to work overtime, which increases fuel consumption.
According to Ocean Life Maintenance Like cars and houses, boats require regular maintenance services to ensure safe, reliable operation. In addition to the standard boat cleaning and waxing, there are more substantial services, such as hull washdowns, brightwork (wood surfaces and trim) care, canvas cleaning, and equipment maintenance. These more extensive services can cost $10-$40 per foot, depending on the size of the vessel. 
Annual trailer maintenance is also required to keep your boat in good working order. This service includes a full inspection and repair of the wheel bearings, tires, electrical connections, and skids.
It is also important to check the condition of the keel and rudder. They need to be free of rust and have no severe abrasions or cracks.
Lastly, the battery should be checked to ensure that it is charged and has no physical damage. Also, the fuses should be replaced as needed to avoid damage to the wiring. The anodes should also be checked and replaced as needed to protect the underwater metal components of the boat from galvanic corrosion.
Other basic boat maintenance services include:
Regular hull washdowns are very important, as warm water encourages barnacle and algae growth. This can damage the hull and shorten its lifespan. A simple hull wash can cost $10-$20 per foot, and is best done on a regular basis. Polishing and waxing are less frequent but very necessary. This process can cost $30-$40 per foot, and may also include canvas and brightwork care.
In addition to the above maintenance items, boats need a complete inspection each year before being put back in the water. This is a thorough process that includes looking at the engine, checking the registration, and paying any fees or fines. Lastly, it is very important to perform a safety check on the boat to make sure all lights, horns and safety equipment are in working condition. It is also a good idea to change the oil after winter and check all fluid levels.