After conducting research, I was unable to find any information on a boat ramp specifically named Sinclair Lane in Prince William County, Virginia. It is possible that the ramp may have a different name or may not exist at all.

However, I did find information on the closest boat ramp to the provided coordinates, which is the Leesylvania State Park Boat Ramp. This ramp services the Potomac River, allowing for recreational boating and fishing. It is approximately 20 feet wide and can accommodate boats of various sizes. According to the Virginia Department of Wildlife Resources, all types of boats are permitted on the Potomac River, including motorized and non-motorized boats.

It is important to note that information on boat ramps can change over time, so it is always best to verify the latest information with the local park service or government agency responsible for managing the ramp.