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This is an endless discussion. The simplest way is to have it done without any real heavy tools. Grinders and blasting will leave their signatures.
As to how difficult:
Much depends on the size of your boat.
How much paint and what type is on the boat?
Some comes off very easily while others are really thick and difficult to remove. Then there are layers.
How much time do you have?
Do you have a place to work on the boat?
Are you willing to get real dirty?
Most of the anti-fouling paints are toxic, so you need protective clothing and masks.
Do you have a means to lift the boat off the trailer? etc.......
I would try a small spot with 80 grit, then 80 grit wet, both on a sanding pad with soft backing.
Then you will know a lot of the answers.

There is one means that has some appeal; Go fishing and contemplate the problem, while it wears off.
Good Luck!