Ship's Weight: Lightweight, Deadweight, and Displacement l Ship Stability Basics

Summary

This video explains key terms related to a ship's weight and capacity, starting with 'lightweight,' the ship's weight without cargo, fuel, or passengers. It then discusses 'dead weight,' the total carrying capacity, which includes cargo, fuel, and passengers. The concept of displacement is also covered, including light ship displacement (empty weight) and loaded displacement (full load weight). The video walks through calculations for dead weight and displacement, with examples to illustrate how these terms apply in practice. Viewers will understand the importance of these metrics in ship stability and operation.

Takeaways

• 😀 Lightweight refers to the ship's weight without cargo, fuel, ballast, provisions, crew, or passengers. It includes the ship's structure, machinery, and fixed parts.
• 😀 Dead weight is the total carrying capacity of the ship, including cargo, fuel, provisions, fresh water, ballast, crew, and passengers.
• 😀 Displacement represents the total weight of the water displaced by the ship when floating, which equals the weight of the ship and everything onboard.
• 😀 Lightweight and light displacement are often considered synonymous, as they both refer to the weight of the empty ship.
• 😀 Dead weight is calculated as the difference between the ship's displacement at full load and its lightweight.
• 😀 Displacement can be measured in metric tons or cubic meters, depending on whether the weight or volume of displaced water is being calculated.
• 😀 When a ship is fully loaded, its displacement is equal to its lightweight plus its dead weight.
• 😀 Hydrostatic tables in the stability booklet help determine the ship's displacement based on its current draft.
• 😀 A ship's displacement at a specific draft can be used to calculate the weight of the load currently onboard.
• 😀 The example in the script shows that for a ship with a lightweight of 10,000 metric tons and dead weight of 50,000 metric tons, the total displacement when fully loaded is 60,000 metric tons.

Q & A

What is the lightweight of a ship?

The lightweight of a ship is the weight of the ship itself without any cargo, fuel, ballast, provisions, crew, or passengers. It includes the weight of the hull, machinery, equipment, and any fixed part of the vessel.

How is lightweight typically measured?

Lightweight is typically measured in metric tons and represents the empty weight of the ship.

What is the difference between lightweight and light displacement?

Lightweight refers to the weight of the empty ship, while light displacement refers to the weight of the ship when it is floating in the water with no cargo, fuel, passengers, or consumables aboard. In most cases, they are considered synonymous.

What does dead weight represent on a ship?

Dead weight represents the total carrying capacity of the ship, including cargo, fuel, provisions, fresh water, ballast water, crew, and passengers. It is the difference between the ship's displacement at full load and its lightweight.

How is dead weight typically expressed?

Dead weight is usually expressed in metric tons and indicates how much weight a ship can safely carry when fully loaded.

What is the formula for calculating dead weight?

Dead weight is calculated using the formula: Dead Weight = Loaded Displacement - Lightweight.

What are the two types of displacement mentioned in the script?

The two types of displacement are light ship displacement and loaded displacement. Light ship displacement refers to the weight of the empty ship (equal to the lightweight), while loaded displacement refers to the weight of the fully loaded ship, including all cargo and other onboard weight.

How is displacement measured?

Displacement can be measured in metric tons or in cubic meters for the volume of displaced water.

How do you calculate the total displacement when a ship is fully loaded?

The total displacement when a ship is fully loaded can be calculated by adding the ship's lightweight and dead weight. For example, if a ship has a lightweight of 10,000 metric tons and a dead weight of 50,000 metric tons, the total displacement would be 60,000 metric tons.

What resources can provide detailed information about a ship's displacement and dead weight?

Details about a ship's displacement, lightweight, and dead weight can typically be found in the ship's stability booklet and general particulars.