Posted on 01 August 2011 at 09:25h

Although this week has been sunny at last the rest of the summer has been overcast and rainy, good weather for fishing. Where I live there are many possibilities for fishing both in salt and fresh water. My particular passion is fly-fishing but due to an elbow injury have had to limit myself to a lightweight fly rod that I can cast without pain. The rod is very thin so bends quite a lot even with a small fish on the hook. One of the functions of the flexible rod is to prevent the line breaking when the fish tries to get away. When fly fishing for trout the last bit of the line is very thin with a breaking strain of only a couple of kilogrammes, however it can be used to catch fish that are both heavier and capable of exerting more force. When the fish tries to pull away, the rod bends, this makes the time of acceleration greater and hence the force less (F=m(v-u)/t). To get the fish on land it either has to be dragged into shallow water and picked up or netted with a landing net (in my dreams).

There is a lot of interesting physics in fly-fishing; The way the tapered rod bends, the stretch of the line and most interesting, the flight of the line. There are many different types of cast but the one I use the most is called the single haul. In this cast the line is taken in with the free hand just before it is propelled forwards, this gives the line more speed sending it out further. To cast well the weight of the line must be matched to the rod, the weight distribution of the line is also important, line with weight forward seems easier to cast further. Lots of interesting EE topics here, pity I only have 2 candidates this year. maybe I'll have to do another one myself.