The Heavy Fire Raft is the second upgrade of the Fire Ships unit class. It becomes available in the Medieval Age and is built at the Dock. Heavy Fire Rafts, like all Fire Ships, are weak ships loaded with explosives, intended to detonate when they hit an enemy ship or structure. Enemy ships will usually take heavy damage or are immediately destroyed. All Fire Ships are effective against Heavy Ships and Bombardment Ships, but can be countered with Light Ships.