How to Calculate Dead Weight

How to Calculate Dead Weight
••• Tryaging/iStock/GettyImages

Dead weight (often referred to as Dead Weight Tonnage or DWT) is a term used to measure the carrying capacity of a ship . It refers to the difference between the ship's displacement while full and while empty. Put another way, dead weight describes the weight of everything aboard the ship: passengers, crew, cargo, ballast, provisions and fuel. This is an important figure for anyone involved in shipping to understand and is relatively simple to calculate.

Calculating Dead Weight Directly

    Note down all provisions and cargoes being loaded onto the ship.

    Add together the weights of each piece of cargo, each passenger or crew member, and all provisions that have been loaded onboard.

    Calculate the weight of fuel. This is done by multiplying the volume of fuel taken aboard by its density. Calculations are commonly done in metric units. Fuel oil has a density of 890 kilograms per cubic meter, meaning that a ship that has loaded 1 cubic meter (or 100 liters) of fuel has added 890 kilograms to its weight.

    Add the fuel weight to the weight of cargo, passengers and provisions to calculate total dead weight.

Calculating Dead Weight by Displacement

    Find the ship's displacement marks. These are white ruler lines on the bottom of the bow and stern of the hull.

    Note which displacement line is sitting at the water level before loading the ship.

    Load the ship with all crew, cargo, fuel and provisions.

    Note which displacement mark is now at the waterline.

    Consult the ship's displacement tables, which have formulas to calculate how much water has been displaced based on the shape of the ship's hull. Because the weight of the displaced water is equal to the weight loaded onto the ship, that is the dead weight.

    Things You'll Need

    • Ship
    • Draft marks
    • Calculator or computer

Related Articles

5 Space Science Kits That Are Out of This World
How to Calculate The Underwater Volume
How to Calculate Buoy Floatation in the Water
How to Calculate the Force Needed to Move a Railroad...
How to Calculate Weight Per Linear Foot
How to Tell if an Object Will Sink or Float
How to Find Mass in Weight
How to Calculate Proportionality
Tractor 574 International Specifications
Specifications of the E-Z-Go Engine
How Does a Hydraulic Dump Truck Work?
Gallons to Kilograms Conversion
What are Gehl 4625 Skid Steer Specifications?
How to Calculate Weight of Plastic
How Can the Study of Density Be Used in the Real World?
How to Convert Newtons to Kilogram-Force
How to Convert Metric Tons to Cubic Meters
How to Calculate Hydraulic Cylinder Tonnage
How to Calculate Rebar Lengths
How Does Thrust Affect Aerodynamics?
Mustang Skid Loader Specifications