After conducting research, it appears that the Yellow River Log Lake Road 3900 boat ramp is a concrete ramp located on the Yellow River in Holt, Florida. The width of the ramp is not specified in the available information.

According to the Florida Fish and Wildlife Conservation Commission, the Yellow River is a freshwater river that flows for approximately 118 miles through the Florida Panhandle. The river is known for its clear, spring-fed waters and is popular for fishing and boating activities.

As for the types of watercraft permitted on the Yellow River, it appears that there are no specific restrictions mentioned for the section of the river near the Yellow River Log Lake Road 3900 boat ramp. However, it is important to note that boaters should always follow Florida boating laws and regulations, including the use of life jackets, navigation lights, and proper boat registration.

In conclusion, based on the available information, the Yellow River Log Lake Road 3900 boat ramp is a concrete ramp located on the Yellow River in Holt, Florida. The width of the ramp is unknown, and there are no specific restrictions mentioned regarding the types of watercraft permitted on the river near the ramp.