American PGM gunboats and the PT-boat speed mismatch

The American section asks why a navy associated with speed and firepower produced such awkward gunboat support for its PT boats. PG-1 conversions began with S-497-class submarine chasers designed for convoy escort and patrol at only about 21 knots. Their 3-inch gun, 40 mm weapon, heavy machine guns, and mortar looked suitable in isolation, but a 40-knot PT force had to slow during the approach and again after launching torpedoes if the gunboat was to remain useful. The larger PGM-9 class was slower still despite carrying heavy gun and rocket armament, and it found a better role supporting and protecting minesweepers. The design mismatch helps explain the celebrated tendency of PT crews to improvise extra weapons on their own boats: the fast craft adapted because their assigned fire-support vessels could not keep up.