Boat Draft Calculator

Formula

To calculate the Boat Draft (DR):

\[ DR = \left( \frac{W}{D} \right) / (L \times W) \times 3 \]

Where:

\(DR\) is the Estimated Draft in feet
\(W\) is the Weight of the boat in pounds
\(L\) is the Length of the boat in feet
\(W\) is the Width of the boat in feet
\(D\) is the Density of the water in pounds per cubic foot

Note: This draft does not include motors or rudders. Those should be added to the total draft.

What is Boat Draft?

Boat draft is a measure of the distance from the waterline to the bottom of the hull. It is used to estimate where a boat can travel safely based on water depth. Boat draft is dependent on the overall shape of the boat, the weight of the boat, and the density of the water (i.e., saltwater or freshwater).

Example Calculation 1

Let's assume the following values:

Weight of the boat (\(W\)) = 2000 lbs
Length of the boat (\(L\)) = 20 ft
Width of the boat (\(W\)) = 8 ft
Density of the water (\(D\)) = 62.4 lbs/ft³

Using the formula:

\[ DR = \left( \frac{2000}{62.4} \right) / (20 \times 8) \times 3 = 0.48 \text{ ft} \]

The Estimated Draft is 0.48 ft.

Example Calculation 2

Let's assume the following values:

Weight of the boat (\(W\)) = 5000 lbs
Length of the boat (\(L\)) = 25 ft
Width of the boat (\(W\)) = 10 ft
Density of the water (\(D\)) = 62.4 lbs/ft³

Using the formula:

\[ DR = \left( \frac{5000}{62.4} \right) / (25 \times 10) \times 3 = 0.96 \text{ ft} \]

The Estimated Draft is 0.96 ft.