After conducting research, I was unable to find any information regarding a boat ramp named Madison County at the given latitude and longitude coordinates in Montana. It is possible that this boat ramp does not exist or that the provided coordinates are incorrect.

In general, a boat ramp refers to a structure or facility designed to launch and retrieve boats from a body of water. Boat ramps can vary in size, shape, and functionality depending on their location and purpose. Some boat ramps are designed for small watercraft such as canoes and kayaks, while others may accommodate larger vessels like sailboats and motorboats.

Additionally, the width of a boat ramp can also vary depending on the size of the boats it serves. A wider ramp may be necessary to accommodate larger boats or to provide more space for multiple boats to launch and retrieve simultaneously.

Without specific information about the Madison County boat ramp, it is impossible to determine what size of boats are permitted on the water it services or what body of water it is located on. It is important to consult local authorities and check for any posted signage or regulations before using a boat ramp to ensure compliance with local laws and safety guidelines.