Torsion in ships is caused due to forces which do not pass through the sheer centre line axis of a ship’s hull cross section. Torsion basically tends to twist the vessel just like how we rinse a cloth by twisting it.
Torsional moment has two main components namely –
a) static torsion or still water torsion,
b) dynamic torsion or wave induced torsion.
Other forms of torsional moments arise from
A ship heading obliquely to a wave will be subjected to righting moments of opposite direction at its ends, twisting the hull and putting it in ‘torsion’.In most ships these torsional moments and stresses are negligible but in ships such as large container ships with extremely wide and long deck openings they are significant.