The math has been explained to you here, and you have received copious references to the available published figures and the century-old methods for applying those figures. You simply ignore them. It is no great secret; it's published in books freely available to all, a reference to which I provided pages ago.

Yes, I agree all is very easy - to slow down a heavy (43 000 kg) space ship in space from one high speed to another, little lower high speed, you apply a substantial force on it (eg 97 400 N), e.g. by using a 1960's rocket engine. The rocket engine consumes fuel in order to slow down the space ship. What is the fuel consumption (kg/s) to produce a certain force (N). According my calculations one kg fuel can produce 1.63 MJ energy to produce the required force.

It is not very efficient = more fuel is needed than can be carried, it seems.

Applied to a seagoing ship means that the ship sinks prior departure. Not very nice.

Imagine a 43 tons car on your door step. Imagine the engine you need to accelerate this heavy car to 2 400 m/s speed. It will be quite big. And now you want to brake from 2 400 to 1 500 m/s speed using a brake. You agree it is a big brake.

Or take the Shuttle - about 78 tons - flying at 7 800 m/s speed around the Earth at 400 000 m altitude to/from the ISS. To slow down for going back to Earth, the Shuttle is turned around and the engines are on full blast but the only result is that the altitude becomes lower and the speed increases to 9 000 m/s at 150 000 m altitude ... while you are still going backwards. You are flying backwards! How to stop?

It is not possible. Not even a computer can land the Shuttle. But Captain Mark Kelly managed to do it. I explain how in my presentation. Enjoy.