If you will be taking out a loan, talk to your bank. You may be required to have insurance. Get some price quotes on insurance. Your automobile driving record will play a part in your boat insurance rates. You might need different levels of insurance during the summer months when the boat is being used than when the boat is in storage over the winter.
Storage is definitely an issue to consider in Wisconsin.
If you plan on storing your boat outside your house, make sure local deed restrictions allow this. When calculating the expense of gas it's helpful to know that an average motorboat will use about 5 gallons of gas per hour. The type of boating activity plays a large role. Cruising to your favorite fishing hole and parking the boat for a few hours will not burn nearly as much gas as 3 hours of waterskiing. Remember to include the cost of boat registration which will need to be renewed every three years.