The key factor is that the pilots need to plan for what they hope never happens...an engine failure on takeoff after accelerating past the V1 speed. V1 is the speed by which time the decision to continue flight if an engine fails has been made. It can be said that V1 is the "commit to fly" speed. V2 is the speed at which the airplane will climb in the event of an engine failure. It is known as the takeoff safety speed.

In addition, in an engine out emergency you never turn into the dead engine: if the left engine fails you make right turns, if the right engine fails, you make left turns as you position yourself for an emergency landing back on the runway you just left.

With one engine out, the rate of climb is drastically less than with both engines operating so taking off over the ocean is required so that you don't have to fly over rising terrain if the "wrong" engine fails. That decision is driven by the weight of the aircraft on that particular takeoff and is calculated before flight in a formula that includes the wind direction and speed in addition to the weight and engine out performance data for that aircraft.