After conducting research, I was unable to find a specific "Main boat ramp" in Nebraska with the given latitude and longitude coordinates. However, there are several boat ramps in Nebraska that serve different bodies of water and have varying restrictions for the types of watercraft permitted.

For example, one popular boat ramp in Nebraska is the Branched Oak Lake boat ramp, located near Malcolm, NE (latitude: 41.0965° N, longitude: 96.9570° W). This boat ramp is operated by the Nebraska Game and Parks Commission and provides access to Branched Oak Lake, a popular destination for boating, fishing, and other recreational activities.

According to the Nebraska Game and Parks Commission website, Branched Oak Lake boat ramp is a concrete ramp that is 26 feet wide and has a maximum water depth of 8 feet. Watercraft permitted on the lake include boats, canoes, kayaks, sailboats, and paddleboards. However, the website notes that all motorized watercraft must comply with Nebraska's boating regulations, including having a valid registration and following speed and wake restrictions.

Overall, it is important to research specific boat ramps in Nebraska to determine their location, features, and restrictions. The Nebraska Game and Parks Commission website is a helpful resource for finding information on boat ramps, as well as regulations and safety guidelines for boating in the state.