How are LCF and CT related?

• A. Weight shifts about the LCF can change the draft, affecting CT
• B. They are independent and do not affect each other
• C. CT determines the LCF position
• D. LCF is only a function of hull length

Answer: (A)

The key idea is that trim is controlled by weight distribution about the Longitudinal Center of Flotation. The LCF acts as the pivot point for longitudinal trim, so when you shift weight forward or aft around that point, you create a pitching moment. That pitching changes the vessel’s angle and which parts of the hull are submerged, i.e., it changes the draft at the bow and stern. Because CT is a parameter that depends on how the hull sits in the water (the draft and the buoyant distribution), any shift in weight that alters draft will also change CT. In short, moving mass about the LCF changes the draft, and the draft changes CT.