Dog Boats were the small-craft threat E-boats feared

What did an E-boat have most reason to fear among aircraft, motor boats, destroyers, and sloops?

British motor gun boats posed the greatest danger, especially the heavily armed Dog Boats that hunted Schnellboote at very close range.

Dog Boats carried unusually heavy and accurate short-range firepower for their size. They could reverse the hunter-and-hunted relationship when Schnellboote entered a convoy lane. One explicitly unverified anecdote concerns a Cambridge classicist who reinforced a Dog Boat for ramming and cut an enemy craft apart. The caveat matters, but the story conveys how close and physical this form of coastal combat could become.