After conducting research, I was unable to find any information specifically about the boat ramp named CR 390 Chaffee County. It is possible that this boat ramp may be a local or lesser-known facility, and therefore may not have readily available information online.

In general, boat ramps can vary in size and type depending on the location and the body of water they service. Some boat ramps may be concrete, while others may be gravel or dirt. They may also vary in width, typically ranging from 10 to 20 feet or more.

As for the body of water that the CR 390 boat ramp services, it is unclear without further information. Colorado has many lakes and rivers, each with their own boat ramps and regulations.

The types of craft permitted on the water will also depend on the specific regulations of the body of water and the local governing authorities. Some bodies of water may only allow non-motorized boats, while others may permit motorized boats of a certain size and horsepower.

Without more information, it is difficult to provide a detailed description of the CR 390 boat ramp and the regulations surrounding it. It is advisable to contact local authorities or the Chaffee County government for further information.