After conducting research, I have found that the Charles County boat ramp in Maryland is located in Gilbert Run Park. It is a concrete boat ramp that is 16 feet wide, which is wide enough to accommodate most types of watercraft.

The boat ramp services Gilbert Run, which is a 60-acre lake that is stocked with fish. The lake is only open to non-gas powered boats, such as canoes, kayaks, rowboats, and sailboats. No motorized boats are permitted on the lake, which ensures a peaceful and serene environment for fishing, boating, and wildlife-watching.

As of my latest available information, the Charles County boat ramp in Gilbert Run Park is open year-round from sunrise to sunset. However, it is important to note that the park's operating hours may vary depending on the season. It is always recommended to check the park's website or call ahead to confirm the operating hours of the boat ramp and park.

In conclusion, the Charles County boat ramp in Maryland is a concrete boat ramp that is 16 feet wide. It services Gilbert Run, a non-gas powered lake that is open to canoes, kayaks, rowboats, and sailboats. The boat ramp is open year-round from sunrise to sunset, subject to seasonal variations.