Space

Okay, I had a weird thought and I need an adult to check the math. Let's say I'm in a magical indestructible spaceship and want to go somewhere far away. I travel to the nearest black hole and fall into it at just the right angle that I continue to accelerate at g for 12 years or so getting to 99+% light speed. At the right moment, I boost out towards my destination, possibly in another galaxy where I catch myself on another black hole (at the *precise* angle) and spend 12 years spinning back down to a neutral dilation context. Using this method I can travel between any two black holes in the universe in about 25 years from the internal dilation context.

Next step is thinking about doing this with Von Neuman probes, and then thinking about who else is going to start doing this too.

Is it even possible to fall like that into a gravitational well? A sustained slingshot effect? And doing it in reverse? If so, it seems like black holes would be popular transit hubs.

I have zero technical competence here, but what would you use to "boost" yourself that you could push out of the gravitational pull of a black hole?