When using a single rod without claiming a peg I can only use rod number 1. The only way to switch to rod 2 and 3 is by claiming a peg.
Its a bit annoying when you have to do that its a big problem on the union canal even more annoying if you wish to switch rods more than once you have to keep claiming a peg where for example on the canal it seems that you can free roam more easily than some other lakes , maybe they will look at it for a future update , I also find for example if your fishing by the bridge on the canal you have to stand in a certain point to cast the area for casting is very limited , its the same on the boat the casting area is limited where you have to stand it needs tweaking slightly to allow more freedom of movement , maybe future updates