Question:medium

The weight of a ship is uniformly distributed along its length.
Under which ONE or MORE of the following conditions will the ship be subjected to hogging moment?
Note: The weight is equal to buoyancy in all of the following conditions.

Show Hint

Picture whether the extra upward push sits in the middle or at the ends of the ship in each case.
Updated On: Jul 28, 2026
  • When buoyancy per unit length is greater than weight per unit length amidships
  • When weight per unit length is greater than buoyancy per unit length in the bow and stern region
  • When the ship is on a single wave with its crest at midship and troughs at the bow and stern
  • When the ship is on a single wave with its crests at the bow, stern and the trough at midship
Show Solution

The Correct Option is A, B, C

Solution and Explanation

Longitudinal bending of a ship's hull depends on how buoyancy support is spread along the length compared with the uniformly spread weight. Hogging always means relatively more upward support in the middle and relatively less at the ends.

  1. Buoyancy per unit length greater than weight per unit length amidships: correct. Extra buoyant lift in the middle pushes the center of the hull up faster than the ends, arching it into a hog.
  2. Weight per unit length greater than buoyancy per unit length at the bow and stern: correct. If the ends carry more weight than the local buoyancy can support, they sink relative to the middle, which is again the hogging shape, just described from the ends instead of the middle.
  3. Wave crest at midship, troughs at bow and stern: correct. A crest amidships raises the local waterline and buoyancy there while the bow and stern sit lower in troughs with less buoyant support, giving the classic hogging wave profile.
  4. Wave crests at bow and stern, trough at midship: wrong. Here the ends get the extra buoyant support from the crests while the middle sits in the trough with less support, which bends the hull the other way into a sagging shape, not hogging.

So the conditions that hog the ship are A, B and C; option D instead describes sagging.

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