There are different type of trolling. There is the type when you put on your heavy sinking line, place the rod into the rod holder, set the motor to whatever speed you want or for some, it can be done while you row as well. This is how I learned how to fly fish, and this type of fishing can be effective. I have done this often when I am fishing with my father in his boat who isn't a sophisticated fly fisher and enjoys exploring different areas of the lake and just likes fishing from his boat. Simple and can be effective. But it does seem like the fish have to on the bite or extremely active to have huge successful days. Also for me, feeling the bite/strike is a my preference, so holding it is important to me, but tough to do obviously if you are rowing.
But when fishing Stillwater, my preference is in my 9 foot pontoon boat with my extra big flippers. Technically I guess I am trolling, paddling along but I am still active, casting and retrieving. I vary my trolling speed (how fast I am paddling), sometimes moving fairly quickly when needed, which can be a workout especially on windy days, or sometimes moving very little or not at all, all depending on how deep I want to fish and the movement of fly. Also, I have three rods rigged up, usually a Midge-Tip or Hoover line for those fish on top and when I fish that rod I am not really trolling much, just slowing paddling as I keep a position but I am doing much more casting and retrieving into shoals or into the bank.
My second rod is a Intermediate or Type III which I guess is the one that I use to troll more, but I am still doing some retrieving and casting.
My third line is a Type V which when fishing I have a tendency to slow down my troll as more often there is no or very light wind and my focus is to get the fly deep so my trolling speed really deceases. This process allows you to do some good wind drifting as well, allows your flipper to act as a rudder and give you some steering and control.
I enjoy the physical aspect of this kind of fishing. After paddling around a lake for a few days, especially in the wind, you get a decent work out which I am looking for. I enjoy exploring lakes as well, I don't like to stay in one area too long unless the fishing red hot in that area. Also, this type of fishing allows me to hold onto the rod and feel the bites and the strikes which is crucial. I don't enjoy anchoring and watching indicators. I do put the rod into the rod holders when I am rowing from one point to the next and I have caught a few fish this way, but I don't see this as being sustainable plus you miss the feel of the strike.
When I go on some annual trips with my friends and family, I am the only pontoon boat without a motor. My brother-in-law and nephew troll a lot and been very successful, out fishing me often. They find the right line, usually a Type III, right speed and they do a good job of finding the holding zone and when they do, it is rinse and repeat for them and I am trying my best to paddle or retrieve my line to match their speed/process and going a little nuts in doing so

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Peach