After conducting research, it appears that the boat ramp named Tarentum in Pennsylvania is located on the Allegheny River at Tarentum Borough Park. According to the Pennsylvania Fish and Boat Commission, the ramp is a single-lane concrete ramp with a maximum width of 20 feet. It is also equipped with a courtesy dock for loading and unloading passengers.

The Tarentum boat ramp provides access to the Allegheny River, which spans over 325 miles from its headwaters in New York down to Pittsburgh, Pennsylvania. The river is known for its recreational opportunities, including boating, fishing, and kayaking.

As for the types of watercraft permitted on the Allegheny River at Tarentum, the Pennsylvania Fish and Boat Commission states that motorboats, canoes, kayaks, and other non-powered boats are allowed. However, it is always important to verify any restrictions or regulations in place before launching a watercraft.