I'm trying to set up a chart of accounts for a branch of a city government, but am unsure as to how to do it. My best idea so far is to enter our yearly budget in as an opening balance, and then journal entries from there. As a Marina, we do have income, but operate on a yearly budget from the city. Has anyone done this yet?

Set up your $ from the city as a revenue account, just like other monies you collect. Then receive the $. You can set up your budgets in the same accounts. If you need help establishing a Chart of Accounts - look at your old manual ledger and go from there or speak to an accountant.
Good luck.