What will cause the free surface effects of...

🔍 Key Concepts

• Free surface effect and how liquid in a slack (partially filled) tank shifts when the vessel heels or rolls • How moment of inertia of the liquid surface changes with the dimensions (length/width) of the tank • The difference between properties of the vessel as a whole (draft, displacement) vs. properties of the tank and liquid

💭 Think About

• Ask yourself: which option directly affects how FAR the liquid can move side-to-side inside the tank when the ship heels? • Which factor will change the heeling moment caused by the shifting liquid, rather than just changing how heavy or deep the ship is overall? • Which answer choice is about the geometry of the liquid surface in the tank, not about the ship’s overall size or loading condition?

✅ Before You Answer

• Identify which choices are about the ship’s characteristics (draft, displacement) versus the tank’s characteristics • Focus on the factor that alters the width/area of the liquid surface that can shift, because that increases the free surface moment • Verify which option would make the free surface moment of inertia larger, thereby worsening stability when the vessel is in motion

What will cause the free surface effects of a partially full tank on a vessel in motion to increase?

The draft of the vessel

The surface area of the fluid in the tank

The height of the tank above the keel

The displacement volume of the vessel

🔍 Key Concepts

💭 Think About

✅ Before You Answer