A peak tank is a ballast tank located at the very forward end (fore peak tank) or very aft end (aft peak tank) of a vessel’s hull.
Fore Peak Tank
Located immediately behind the collision bulkhead at the bow, the fore peak tank serves two functions:
- Trim adjustment — water can be added or removed to help fine-tune the vessel’s trim
- Structural protection — combined with the collision bulkhead, it provides a buffer zone at the bow specifically designed to contain flooding from a bow collision without immediately affecting cargo holds further aft
Aft Peak Tank
Located at the stern, the aft peak tank similarly assists with trim control and provides structural protection around the stern area, including around the rudder stock and propeller shaft penetration through the hull.
Trim Control Function
Peak tanks are commonly used as the primary trim-adjustment tool during loading — since they sit at the extreme ends of the vessel, relatively small volume changes in a peak tank have a proportionally larger effect on trim than the same volume change would have in a more centrally located tank.
Structural Significance
Both peak tanks are integral to a ship’s SOLAS-mandated damage stability provisions — their specific positioning and the collision bulkhead’s location relative to the fore peak tank are governed by regulatory requirements, not arbitrary design choices.
Exam Relevance
Peak tank functions, trim adjustment using peak tanks, and their structural role are core Ship Stability and Ship Construction topics in deck officer competency exams.