This is the name given to the in and out movements of the plates at the forward and after ends of a ship caused by changes in water pressure as the waves pass along the ship.

Panting derives from stresses on the ship produced by the vibration of the plating and framing in the positions that are especially liable to fluctuating water pressure when the ship is at sea.

Panting is an in-and-out movement of the shell plating resulting from the variations of water pressureas waves pass along the hull and when the vessel pitches.

The location of the greatest stresses is at the bow when making headway.

These are greatest in fine bowed vessels.

Classification Societies' Rules require extra beams, brackets, stringer plates, etc. to be fitted at the forward and after ends in order to reduce the possibility of damage.

Obviating panting is more a question of providing sufficient stiffness than adding strength.

All side plating must be sufficiently stiff, especially at the ends where as a result of pitching, the vibrations of pressure on the plating are most pronounced.

This applies more at the front end than at the after end, with the additional stiffening taking the form of stringers welded to the shell and of heavy riveted frames.Forward of the collision bulkhead, in the fore peak tank, solid floors are fitted to every frame, with stringers and vertical intercostal plates tying them together.

In large ships the stringers are carried after into the first hold, and where a deck has been deleted in the chain locker, continuity is maintained by the fitting of stringers at the deck level.

The method adopted depends upon the size and form of the ship and the unsupported depths of side framing.

Similar conditions exist, but to a lesser degree, at the after end of a ship, and stiffening must be provided to prevent any development in the movement of the framing.Particular care must be taken in connecting the propeller castings to the floors and shell of twin screw ships.

The necessary compensation against these stresses are:

-tiers of panting beams spaced 2m apart vertically and fitted on alternate frames, and supported by centre line pillars,
-stringer plates at each tier of beams (at the same level as the beams).

The stiffening is amde up of horizontal side stringers, known as panting stringers, fitted at about 2m intervals below the lowest deck.Panting beams are fitted across the ship at alternate frame spacesand are bracketed to the panting stringer.The intermediate framesare connected to the panting stringers by brackets.A partial wash bulkhead or a series of pillars is fitted on the centreline to further support the structure.Perforated flats may be fitted instead of beams but these may not be more than 2.5m apart.Perforations of at least10% of the plate area are required in order to reduce water pressure on the flats.

Compensation extends from forward to collision bulkhead (0.15L) and in after peak.

Strengthening is fitted from forwards to 0.15L (or 0.20L).The collision bulkhead is fitted at 0.15L.Extending stringer back into no 1 hold takes up space.Therefore the alternative of shell plate thickening is adopted.

The regions required by Lloyd's Register to have special strngthening to resist panting are the after peak tank and the portin forward of 0.15L from the fore end.

The frame spacing is generally 24in. in the peaks and 27in. in the remainder of the panting region, except in small vessels where it is less.

In the peaks, besides deep floors, tiers of beams on alternate frames are to be fitted below the lowest deck in association with stringer plates spaced 6ft apart in the fore peak and 8ft apart in the after peak.Where these stringers are not attached, the shell is required to be of increased thickness.

In the remainder of the panting region the side frames and their lower end attachment are increased in strength.The frames are attached to the shell by rivets spaced 5.5 diameters apart or by equivalent welding.Side stringers in line with those in the fore peak are to be fitted.These generally take the form of intercoastal plates in conjuction with face falt stringers fitted at the line of the frame.These stringers may be omitted if the shell is suitably increased.The arrangement of stringers in deep tween tanks is generally similar.

In the fore peak, side stringers are fitted to the shell at intervals of 2m below the lowest deck.No edge stiffening is required as long as the stringer is connected to the shell, a welded connection being used in modern ships.The side stringers meet at the fore end, while in many ships a horizontal stringer is fitted to the collision bulkheadin line with each shell stringer.This forms a ring round the tank and supports the bulkhead stiffeners.Channel beams are fitted at alternate frames in line with the stringers, and connected to the frames by brackets.The intermediate frames are bracketed to the stringer.The free edge of the bulkhead stringer may be stiffened by one of the beams. In fine ships it is common practice to plate over the beams, lightening holes being punched in the plate.

The tank top is not carried into the peak, but solid floors are fitted at each frame.These floors are slightly thicker than those in the double bottom space and are flanged on their free edge.

The side frmaes are spaced 610mm apart and, being so well supported, are much smaller than the normal hold frames.The deck beams are supported by vertical angle pillars on alternate frames, which are connected to the panting beams and lapped onto the solid floorss.A partial wash-plate is usually fitted to reduce the movement of the water in the tank.Intercostal plates are fitted for two or three frame spaces in line with the centre girder.The lower part of the peak is usually filled with cement to ensure efficient drainage of the space.

Between the collision bulkhead and 15% length from forward the main frames, together with their attachment to the margin, are increased in strength by 20%.In addition, the spacing of the frames from the collision bulkhead to 20% of the length from forward must be 700mm.Light side stringers are fitted in the panting area in line with those in the peak.These stringers consist of intercostal plates connected to the shell and to a continuous face angle running along the toes of the frames.These stringers may be dispensed with if the shell plating is increased in thickness by 15%.This proves uneconomical when considering the weight but reduces the obstructions to cargo stowage in the hold.The peak is usually used as a tank and therefore such obstructions are of no importance.

The collision bulkhead is stiffened by vertical bulb plates spaced about 600mm apart inside the peak.It is usual to fit horizontal plating because of the excessive taper on the plates which would occur with vertical plating.

The structure of the after peak is similar in principle to that in the fore peak, although the stringers and beams may be fitted 2.5m apart.The floors should extend above the stern tube or the frames above the tube must be stiffened by flanged tie plates to reduce the possibility of vibration.

Copyright ©, 1997 Marinet