## What Does FSW Mean in Scuba Diving?
### Introduction
“FSW” is a common abbreviation used in scuba diving. It stands for “feet of seawater”. This unit of measurement is used to indicate the depth of a dive. FSW is different from feet of water (FOW), which is used to measure the depth of a body of water.
### Understanding FSW
Definition: FSW is a measurement of the depth of water, expressed in feet.
Calculation: FSW is calculated by dividing the atmospheric pressure at the surface by the specific gravity of seawater. The specific gravity of seawater is 1.025.
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FSW = (Atmospheric pressure in psi) / 1.025
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Example: If the atmospheric pressure is 14.7 psi, then the FSW is 14.34 feet.
### Why Use FSW?
FSW is used in scuba diving for several reasons:
Consistency: FSW provides a consistent way to measure depth, regardless of the salinity or temperature of the water.
Accuracy: FSW is a more accurate measurement of depth than FOW, as it takes into account the specific gravity of seawater.
Safety: Using FSW helps divers to accurately gauge their depth and avoid exceeding their maximum depth limits.
### Comparison with FOW
FOW and FSW are both used to measure depth, but there are some key differences between the two units:
| Characteristic | FOW | FSW |
|—|—|—|
| Definition | Depth of water | Depth of water adjusted for the specific gravity of seawater |
| Calculation | Vertical distance from the surface | Atmospheric pressure divided by the specific gravity of seawater |
| Accuracy | Less accurate | More accurate |
| Use | Not commonly used in scuba diving | Used in scuba diving to measure the depth of dives |
### Practical Applications of FSW
FSW is used in a variety of practical applications in scuba diving, including:
Dive planning: Divers use FSW to plan their dives, including the maximum depth they will reach.
Dive logs: Divers record their dives in dive logs, which include the FSW depth of each dive.
Buoyancy control: Divers use buoyancy control to precisely adjust their depth underwater. FSW helps divers gauge their depth and adjust their buoyancy accordingly.
Decompression calculations: Decompression calculations are used to determine the amount of time a diver needs to spend at various depths during decompression stops. FSW is used in these calculations to ensure that the diver stays within safe decompression limits.
### Conclusion
FSW is an important measurement in scuba diving. It provides a consistent, accurate, and safe way to measure depth underwater. Divers should be familiar with FSW and its applications to ensure safe and enjoyable dives.