One doesn't ever tip one's ship, at least not too far (15% is acceptable), lest one scuttles it! With the exception of, maybe, a canoe, especially if one should want to lay tile in it. A tip of a hat or an iceberg is permittable, though.

Tipping drummers only leads to them getting delusions of being Gene Krupa, or Keith Moon. Not a good move for a galley slave.