Which patrol gunboat class was the U.S. Navy's first entry into the marine gas turbine field?

The Asheville class patrol gunboats represent the U.S. Navy's first venture into utilizing marine gas turbine technology. This class was designed to incorporate advanced propulsion systems that enabled higher speeds and improved operational capabilities compared to traditional propulsion methods.

The decision to implement gas turbines in naval vessels like the Asheville was driven by the desire for faster, more agile ships capable of performing a variety of missions, including coastal patrol and interdiction operations. The efficiency and power-to-weight ratio of gas turbine engines provided significant advantages, making the Asheville class an important milestone in naval design.

Other classes mentioned, such as the Pittsburgh, Blue Ridge, and Riverine, do not reflect this pioneering aspect in terms of marine gas turbine technology, as they were either designed earlier or focused on different operational roles that did not incorporate this technology. Therefore, the Asheville class is recognized as the correct answer for its role in ushering in the era of gas turbine propulsion in the U.S. Navy.