Bomb Vessel. This ship gets +1 to her cannon rolls against American ships and forts.Bomb Vessel: Ramming cannot eliminate this ship's masts. This ship has an additional rank-4 mortar cannon assigned to each of its first two masts. These mortars can only shoot once per turn each, and can only hit targets more than L away but not more than L+L away. These shots are not blocked by other ships, and get +1 to their rolls when targeting a fort. If a mortar shot hits, replace a mast on the enemy ship with a fire mast instead of eliminating it; if the mortar roll is a 1, replace that mast on this ship with a fire mast. The following cannot be applied to these mortar shots: specialists, grape shot, chain shot, smokepot shot, other abilities that improve cannon accuracy.