>>3573800>I don't place much faith in that guy's calculations. He has had to amend the result several times because of incompleteness etc.
Each time he's just adding more moving mass to the calculation, making it less favorable for his point.
>fails to take into account motion might continue longer because of momentum.
The acceleration has to take place while the force/impulse is acting. It's possible that the ship -eventually- moves 30 feet, but the impulse will only impart a maximum recoil speed around 0.5 feet per second assuming no friction or resistance, just pure transfer of momentum, so it would have to do so over a full minute. With the entire ship pushing broadside against millions of tons of water, it's not going anywhere.