No, it wont work. The forces will be equal, and opposite.
Creative idea however.
Newton's third law tells you the forces will be equal. If both magnets are attached to the boat it won't go anywhere.
How was the story of Baron Munchausen guy lift himself up by his ponytail from the quicksand. Does not work :)
Yup, Newton's third law is the key concept here. As hard as it may be to believe, the smaller magnet pushes back on the larger one with an equal amount of force.
If not for the validity of Newton's third law , stuff like this would be possible (which it isn't):
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