A storyboard is a term used most often to refer a visual sequencing of the shots of a movie or animated film. The storyboard is meant to show the image that the camera would capture in each frame of its shots. So for example, a storyboard of someone eating an apple might show an apple in a bowl in shot one; a hand reaching into the frame to take the apple in shot two, a mouth biting and chewing the apple in shot three; and an apple core (already eaten) back in the bowl in the final shot.
The shipwreck is an obvious choice for a storyboard, since the storyboard will allow you the freedom to imagine all kinds of pictures of this scene that would never be feasible to present onstage.
I don't think it matters how you mount your board for presentation, just make sure that you are telling the story, in the correct sequence of pictures, that you want to tell. You needn't try to cover every possible angle, only focus what you think is important, visually, to tell the story.