Why did the tide did not bring the coracle to the shore?

The tide pulled the coracle northward, thus, Jim was unable to get the coracle to shore.

I remembered what Silver had said about the current that sets northward along the whole west coast of Treasure Island, and seeing from my position that I was already under its influence, I preferred to leave Haulbowline Head behind me and reserve my strength for an attempt to land upon the kindlier-looking Cape of the Woods.