Which of the following is a reason for a vessel being considered in unsuitable condition?

A vessel is considered in unsuitable condition when it lacks essential safety equipment, such as life jackets for every person on board. Life jackets are crucial for ensuring the safety of all passengers, as they provide buoyancy and help prevent drowning in the event of an accident or capsizing. Without having an adequate number of life jackets, the vessel fails to meet safety regulations and poses a significant risk to its occupants.

In contrast, having additional equipment might be beneficial for certain situations but does not inherently indicate unsuitability. Operating under guaranteed safety checks suggests that the vessel meets required safety standards and is fit for navigation, while safe weather conditions do not affect the vessel's suitability in terms of equipment and safety compliance.