How much protection could a small craft carry?

Could small-craft hulls stop 20 mm fire, and where was armor fitted?

Most small boats had little armor; some British craft protected limited areas, while Steam Gun Boats carried more protection than many lighter counterparts.

Most motor torpedo boats, motor gun boats, and Schnellboote could not rely on broad armor protection. Some British craft protected selected positions, while the much heavier Steam Gun Boats carried more protection around vulnerable machinery and fighting spaces. A light hull exposed to 20-millimeter cannon fire could rapidly lose combat effectiveness. The tradeoff helps explain why detection, maneuver, and firing first were more important than trying to absorb damage.