I like the subject. The rust plays well off the blue sky and water. I think the composition would be improved by cropping out some of the "extra" sky at the top. And the lighthouse seems overexposed and out of focus detracting from the otherwise strong lines.
I would have cropped the sky to just above the rail for more dramatic impact. Still, it's a very nice composition. I like the shadows quite a bit. They add further emphasis to the vanishing point.