Speed Length Ratio Calculator

Calculating the Speed Length Ratio (SLR) of a boat is essential for understanding its performance characteristics relative to its size. The SLR is a dimensionless number that helps in assessing the efficiency of a boat's hull design in moving through water.

Speed Length Ratio Formula

To calculate the Speed Length Ratio, the formula is quite straightforward:

\[ SL = \frac{V}{\sqrt{L}} \]

Where:

• \(SL\) is the Speed Length Ratio.
• \(V\) is the speed of the boat in knots.
• \(L\) is the waterline length in feet.

How to Calculate Speed Length Ratio

Calculating the Speed Length Ratio involves a few simple steps:

1. Determine the Speed of the Boat: Measure or obtain the boat's speed in knots.
2. Determine the Waterline Length: Find out the length of the boat at the waterline in feet.
3. Use the Formula: Apply the values to the formula \(SL = \frac{V}{\sqrt{L}}\).
4. Calculate: Perform the calculation to find the Speed Length Ratio.

Example Problem

Given:

• Speed of the boat = 5 knots
• Waterline length = 20 ft

Calculation: \[ SL = \frac{5}{\sqrt{20}} = \frac{5}{4.4721} = 1.1180 \]

This example shows how to use the Speed Length Ratio formula to determine that a boat with a speed of 5 knots and a waterline length of 20 feet has a Speed Length Ratio of approximately 1.1180. This metric is useful for comparing the potential speed and efficiency of different boat designs.