A vessel aground may have negative GM since...

🔍 Key Concepts

• Grounding and buoyancy – what happens to a ship’s buoyant support when part of the bottom is resting on the ground • Lost buoyancy method – how grounding changes KB, BM, and therefore KM and GM • Virtual rise of G (metacentric height) – when support is partly from the ground instead of from water

💭 Think About

• Think about what GM is (GM = KM − KG). During a grounding, which term actually changes first: KG, KB, BM, or KM? • When a ship takes the ground, is all the support still from water buoyancy? Or is some support now from the seabed? How does that affect KM and the calculation of GM? • Which option correctly describes the mechanism that can make GM negative—i.e., what physical change could make KM drop below KG?

✅ Before You Answer

• Be sure you know that GM becomes negative when KM < KG, not when draft simply changes • Check which answers confuse point of action of displaced water with point of reaction from the ground • Verify which statement correctly links lost buoyancy and reduction in KM to the risk of a negative GM, instead of just mentioning draft or displacement in a vague way

A vessel aground may have negative GM since the __________.

displacement lost acts at the point where the ship is aground

lost buoyancy method is used to calculate KM, and KB is reduced

virtual rise of G is directly proportional to the remaining draft

decrease in KM is equal to the loss of draft

🔍 Key Concepts

💭 Think About

✅ Before You Answer