In a fixed trim basis, how might a GZ curve differ from a free trim basis?

In stability analysis, the GZ curve represents the leverage or righting arm of a vessel at various angles of heel, reflecting the vessel's stability characteristics. In a fixed trim condition, the vessel's trim – the difference in draft between the bow and stern – is held constant. This can lead to a situation where the distribution of weights and the shape of the underwater body affects buoyancy and center of buoyancy differently than when trim is allowed to adjust freely with the angle of heel.

When a vessel operates in a free trim condition, it can adapt to varying angles of heel, which typically results in better utilization of the vessel's underwater form. This can allow for a potentially higher GZ curve since the center of buoyancy may shift more optimally, enhancing the righting moment at increased angles. Conversely, in a fixed trim scenario, the inability to change trim as the vessel heels can limit the effective righting arm, leading to a lower GZ curve due to the stability variations.

Therefore, the notion that fixed trim may lead to a lower GZ curve captures how the constraints imposed by maintaining a specific trim can alter the vessel's dynamic stability characteristics compared to a free trim basis, where the vessel can optimize its balance and stability with changes in