PROVIDENCE, R.I. — Scientists are using submersibles to explore a German U-boat sunk 7 miles off the Rhode Island coast the day before Nazi Germany surrendered in World War II, and they’re streaming the attempts online as they work to learn more about shipwrecks and how they affect the environment. The submarine, U-853, was sunk in the Battle of Point Judith by Coast Guard and Navy ships on May 6, 1945, the day after it took down the SS Black Point, the last U.S.