E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Thrown on my beam-ends. Driven to my last shift. A ship is said to be on her beam-ends when she is laid by a heavy gale completely on her beams or sides. Not unfrequently the only means of righting her in such a case is to cut away her masts.
On the starboard beam. A distant point out at sea on the right-hand side, and at right angles to the keel.
On the port beam. A similar point on the left-hand side.
On the weather beam. On that side of a ship which faces the wind.