Why Do They Call It “Breeches Buoy”?

Breeches Buoy:  This was a life ring with old pants cut off at the knees to fit                                            it.  Men would be carried from their ship to a land location                                            or another ship sitting in the “breeches buoy.” Due to the motion                                of ships, the line would often slacken and the passenger would                                    become drenched.