In a swim, the river decides that you will get out of the boat NOW! You have (or believe you have) no choice but to get-out-now.
In the pin you describe, Patrick realized the boat was stopped. He could have eaten lunch there, just sitting in the boat. He exited the boat ON HIS TERMS, got out, stretched his legs, repositioned the boat, got back in, and continued downstream.
I vote NOT a swim.
"So in two seconds, away we went, a sliding down the river, and it did seem so good to be free again and all by ourselves on the big river and nobody to bother us." -Mark Twain (The Adventures of Huckleberry Finn)