After conducting thorough research, there is no information available about a boat ramp named Madera County in California with the given coordinates (latitude: 37.12261963, longitude: -119.88954163). It is possible that the location may have changed or the information provided is incorrect.

However, there are several boat ramps located in Madera County, California, including the Hidden Dam Boat Launch and the Pine Flat Lake Marina. The Hidden Dam Boat Launch is operated by the United States Forest Service and is located on the San Joaquin River. It provides access to the river for small boats, canoes, and kayaks. The Pine Flat Lake Marina is a public boat ramp located on Pine Flat Lake, which is a popular recreational destination for boating, fishing, and water sports.

The width of the boat ramp at these locations may vary, but typically it is wide enough to accommodate most small and medium-sized boats. The types of watercraft permitted on the water will depend on the specific rules and regulations of each location. It is important to check with the local authorities or the facility operator for the latest information regarding permitted watercraft and any other rules and regulations that may apply.