The liquid mud tanks on your vessel measure...

Question 1 of 2707066636eec28f7522a1c51c655

The liquid mud tanks on your vessel measure 20'L by 18'B by 7'D. The vessel's displacement is 866 T and the specific gravity of the mud is 1.8. What is the reduction in GM due to a pair of these tanks (p/s) being slack?

Back

Question 1 of 27070

🔍 Key Concepts

• Free surface effect and how slack tanks reduce GM • How to compute the moment of inertia of a rectangular tank surface (I = l × b³ / 12 or b × l³ / 12, depending on orientation) • Using specific gravity to adjust from seawater tons to actual mud weight in the tank

💭 Think About

• First, figure out the volume of one mud tank and the weight of the mud it would contain when full, using the specific gravity of 1.8. How does that relate to seawater density? • Recall the standard free surface correction formula for GM: Free surface correction = (ρ_liquid / ρ_seawater) × (ΣI / Δ). Which quantities do you need to plug in here, and how does having two identical tanks, port and starboard, affect ΣI? • Think about the free surface being transverse. Which tank dimension (length or breadth) should be cubed when you calculate the moment of inertia for a transverse free surface?

✅ Before You Answer

• Be sure you are using consistent units (feet for dimensions, long tons for displacement and tank weight). • Confirm that you are using the correct free surface inertia formula for a rectangle with the free surface spanning the breadth (or length) of the tank. • After computing the free surface correction, check that your GM reduction is a reasonable fraction of a foot (not many feet for just two tanks on an 866‑ton vessel).