Subsubsection Volume Units
These are many different units for measuring volume in use, including different units for dry and wet materials. Here we will focus on those volume units relevant to shipboard operations.
US Standard Units.
In the US standard system, volume is typically measured in cubic feet (\(\ft{1}^3\)) or cubic inches (\(\inch{1}^3\)).
The fluid ounce is commonly used for measuring small liquid volumes, especially for cooking. 1 fluid ounce is about 1.80 cubic inches. The gallon is a larger unit of liquid volume, equal to 128 fluid ounces. 1 US gallon has a volume of 231 cubic inches.
The volume of a barrel depends on the type of barrel, so a beer barrel, a whiskey barrel, and an oil barrel are all different. In the marine and petroleum industries, a barrel means an oil barrel (bbl). The standard size for an oil barrel is 42 US gallons (approximately 159 liters). Many liquid products are shipped in drums. The most common sided drum can hold approximately 55 US gallons of liquid, which is roughly equivalent to 208 liters.
Metric Units.
The standard unit for measuring volume in the International System of Units (SI) is the cubic meter (\(\m{}^3\)) or cubic centimeters (\(\cm{}^3\)).
The liter is commonly used for everyday measurements of liquid volumes. One liter is equal to 1 cubic decimeter. The milliliter is a smaller unit used for precise measurements of liquids. One milliliter is equal to one-thousandth of a liter.
The cubic meter(CBM or \(\m{}^3\)) is the standard unit for larger volumes, and is equal to the volume of a cube with sides of one meter.
The Ton.
A ton has a long history and has acquired several meanings and uses. Depending on context, a ton may refer to a unit measure of mass, volume or force.
A metric ton (tonne) is the mass of water which occupies \(\m{1} \times \m{1} \times \m{1}\) cube, and equals \(\kg{1000}\text{.}\)
A deadweight ton is a measure of the weight of cargo a ship can safely carry.
In transportation, the Measurement Ton, or Shipping Ton, is a volume measure equal to one cubic meter (\(\m{}^3\) or CBM) . A CBM is used in the shipping and transportation industries to describe how much space a shipment takes up, i.e. 1 cubic meter . Note that the weight of one cubic meter of water is one metric ton, but the weight of one CBM of other material will vary depending on the material’s density.
