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When you are ready to go boating there are a few resources you will need to ensure a safe and enjoyable day out. Checking the weather, the tides and currents, and filing a float plan should be part of your pre-departure routine.
Washington DC Tides (Official)
Washington DC Currents (Official)
Having good reference guides will make you a better and safer boater. The USCG has downloads available that will help you understand the rules and regulations.