After conducting research, it appears that the boat ramp named County Road 600 South in Montgomery, Indiana is a concrete ramp. The width of the ramp is unclear, as it is not specified in any official documentation. However, it is known that the ramp services the White River, which is a popular destination for fishing and recreational boating.

In terms of the types of watercraft permitted on the water, it appears that there are no specific restrictions. However, it is important to note that Indiana does have regulations in place for boating and fishing on certain bodies of water, including mandatory life jacket use and restrictions on certain types of equipment and bait.

It is important to note that specific rules and regulations regarding boating and fishing in Indiana can vary based on location and current conditions. It is recommended to review the latest information from the Indiana Department of Natural Resources before planning any boating or fishing trips.