Riding on the side wash gives you more speed and/or a bit of a rest, but also presents some risk. The boat that is ahead has the right of way, even if it is only 1 inch ahead. When you are going upstream and following the shoreline, the boat on the shore side usually leads. If the boat on the shore side is not ahead, they are vulnerable to being ‘scraped off’ or driven into the shore, and are better off dropping to stern and riding there. Either boat may decide to do a sprint and try to drop the other boat. It is often better for the boat on the outside to ride a little higher so that they can respond to a sprint.