After conducting research, it appears that there are two locations with the name "Powderhorn" that are related to boating in South Dakota: Powderhorn Recreation Area Boat Ramp and Powderhorn Wildlife Management Area Boat Ramp.

Powderhorn Recreation Area Boat Ramp is located at 13212 349th Ave, Gettysburg, SD 57442, with a latitude of 44.969223 and a longitude of -99.945746. It is a concrete boat ramp that provides access to the Lake Oahe reservoir, which is a popular destination for fishing, boating, and water sports. The boat ramp is reported to be 24 feet wide, which should provide ample space for launching and loading boats. According to the South Dakota Game, Fish, and Parks website, all types of boats are permitted on Lake Oahe, including motorboats, sailboats, kayaks, and canoes, as long as they comply with state and federal regulations.

On the other hand, Powderhorn Wildlife Management Area Boat Ramp is located at 42.6292305, -100.88587952, which is close to Crawford, Nebraska, rather than South Dakota. This location does not seem to have any official information or updates regarding a boat ramp. Therefore, it is unclear what kind of boat ramp it is, how wide it is, what body of water it services, or what kind of craft are permitted on the water.

In summary, Powderhorn Recreation Area Boat Ramp in South Dakota is a 24-foot wide concrete boat ramp that provides access to Lake Oahe reservoir, where all types of watercraft are permitted. However, there does not seem to be any information regarding a boat ramp at Powderhorn Wildlife Management Area in Nebraska.