Wetted Surface Area Calculator

How to calculate the wetted surface area of a boat or ship? The answer of the question is, Wetted Surface Area (WSA) Calculator. Simply enter the water line length, beam, and draft into the calculator, and it will display wetted surface area.

Wetted Surface Area Calculator

Enter any 3 values to calculate the missing variable

Wetted Surface Area Calculation tool

What is Wetted Surface Area?

Wetted Surface Area (WSA) is the part of a ship’s hull that touches the water. It’s important for determining resistance and efficiency in the water, helping to gauge how the vessel will move and perform.

How to Use the WSA Calculator

To use the calculator, follow these steps:

  1. Enter the Water Line Length (ft): The water line length is the length of the boat at the waterline.
  2. Enter the Beam (ft): The beam is the widest part of the boat.
  3. Enter the Draft (ft): The draft is the depth of the boat from the waterline to the bottom of the hull.
  4. Calculate the WSA: Click the calculate button to find the wetted surface area.

Example Input Values

  • Water Line Length: 30 ft
  • Beam: 10 ft
  • Draft: 5 ft

How to Calculate Wetted Surface Area

The formula for calculating wetted surface area is:

WSA=WLL×(B+D)WSA = WLL \times (B + D)


Variable Description
WSA Wetted Surface Area (ft²)
WLL Water Line Length (ft)
B Beam (ft)
D Draft (ft)

Calculation Example

Let’s calculate the wetted surface area with the example values.

1: Identify the values:
WLL=30WLL = 30

ft, B=10B = 10

ft, D=5D = 5


2: Plug the values into the formula:
WSA=30×(10+5)WSA = 30 \times (10 + 5)

3: Perform the addition inside the parentheses:
10+5=1510 + 5 = 15

4: Multiply the results:
30×15=45030 \times 15 = 450

Result: The wetted surface area is 450 ft².

How To Enter Values Into Calculator

1. Basic Calculator

Input Value
Water Line Length (ft) 30
Beam (ft) 10
Draft (ft) 5
Wetted Surface Area 450 ft²

2. Advanced Calculation

Input Value
Water Line Length (ft) 45
Beam (ft) 15
Draft (ft) 7
Wetted Surface Area 990 ft²


What is the wetted surface area used for?

The wetted surface area shows the resistance a boat faces when moving through water. It helps one to understand the boat’s efficiency and performance.

Can I use this calculator for any type of boat?

Yes, you can use this calculator for any boat if you have the waterline length, beam, and draft measurements.

Why is the wetted surface area important?

The wetted surface area affects the hydrodynamic drag on the boat. A larger wetted surface area means more resistance, which can reduce speed and fuel efficiency.

Fine Lines

How was the tool? I hope this calculator helps you easily find the wetted surface area of your boat. Please share your experience and feedback with us in the comment box.

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