If a ship sails at 18.5 knots and has 9,000 horsepower vs a ship sails at 19 knots with 12,000 horsepower?

Question

is it a huge speed and power difference and if so by how much

Answer 1

If the hull design is the same for another half a knot for 3000 more horsepower is a waste of resources.  A half a knot might be something in a race.  Shipping companies are looking for the most profit.  Then only thing is the ship is going to burn more fuel and might beat the other ship to the dock.  The 12000 hp would burn more fuel.  I could almost understand if the ship with more horsepower carried more cargo.

Answer 2

Yes it by 97% I guessing. It is interesting how "Design" can make a difference on the Horse Power.

Answer 3

Speed vs. HP is an exponential function for each ship.  Two different ships cannot be compared.  There are too many variables to create a directly proportional relationship.