For a

displacement boat, the

maximum efficient speed that a particular hull can attain is called

hull speed.
It can be calculated by the formula:

Hull Speed = 1.34 * sqrt(LWL)

Where:

Hull Speed is measured in

knots, and

LWL is the

length at the waterline of the hull in

feet.

For example, a boat with a

waterline length of 500 feet
would have a hull speed of:

1.34 * sqrt(500)
= 30 knots

To achieve this

speed, a boat needs

power of approximately
2-3

horsepower per

ton. To exceed hull speed, a boat
needs 50-100 horsepower per ton.

If the 500 foot boat above weighed 10000 tons, it would
need about 30000

horsepower to travel at 30

knots.
To go faster than 30 knots, the boat would need more than 500000 horsepower.