Peak tanks are those found at the forwards and aft extremities of the ship, that is, forward of the collision bulkhead and aft of the after peak bulkhead.

The construction within these tanks differs from that of the rest of the ship, the reason being that the stresses suffered in these parts is considerably different.

The cellular double bottom arrangement is the rest of the ship is discontinued in these tanks.  Solid floors are fitted at every frame space.  This is essential in the fore peak to counteract pounding stresses. The center girder will be extended for a few floors and discontinued as the width of the bottom gets narrow.

There are two types of Peak Tanks:

1. Fore Peak Tank

2. After Peak Tank

The Fore Peak Tank

Above the floors, a wash plate (not watertight) divides the tank longitudinally into two. 
If the collision bulkhead is corrugated, then no further strengthening is provided for the bulkhead itself, otherwise, suitable stiffening is to be found on the bulkhead, the collision bulkhead forms the after boundary of the Fore Peak Tank.

The side shell plating is either transversely framed (with frames) or longitudinally frames ( with frames ) or longitudinally framed with longitudinals depending on the framing system used in the rest of the ship.

Strengthening against painting is the most outstanding feature of the Fore Peak Tank.  This takes the form of Panting beams and stringers.  The panting stringers are essentially triangular plates bordering the tank horizontally at two or three levels.  These stringers are further reinforce by panting beams as in the figure.  Breast hooks (smaller horizontal triangular plates) are fitted between and at each level of panting stringer.  These provide additional strengthening in the vicinity of the stem.

Usually in the after portion and at a higher level, the Chain lockers will be fitted.  The anchor chain for both anchors is stowed in these lockers, with the ends being secured to the collision bulkhead or other suitable point called the Bitter End.

The After Peak Tank

This compartment extends from the after peak bulkhead to the stern frame and aft end of the ship.  In this tank also, solid floors are fitted at every frame space as additional strength is required here.  The floors are quite deep and the double bottom is discontinued.

There are floors fitted abaft of the higher than the stern frame to support the part of the stern which overhangs the rudder and propeller.  At the head of the rudder of the rudder post an extra-strong floor is fitted called the Transom Floor.  This floor is designed to support the overhanging mass and framework of the stern.

The entire tank is divided longitudinally into two by a wash-plate with lightening holes which runs vertically forwards and aft on the centerline.  The stern tube which house the propeller shaft extends from the after peak bulkhead to the stern frame.  This passes through the after Peak tank.  In the aft portion a rudder turn is provided through which the rudderstock passes.

Access into the after peak tank is by manhole either on the after peak bulkhead or from the top through the steering flat deck.  This tank is usually used for water ballast or sometimes as a fresh water tank.