Complex sentence: Tensile plate strength could not entirely compensate for lack of mass and ships of this class were particularly susceptible to structural damage when operating at speed and frequently suffered machinery casualties due to hull deformation in heavy seas.
Split into simpler sentences: Tensile plate strength could not entirely compensate for lack of mass. Consequently, ships of this class were particularly susceptible to structural damage when operating at speed. They also frequently suffered machinery casualties due to hull deformation in heavy seas.