Hello, I fly fish off a boat for a few years now using a 10 foot 7 weight I wouldn’t say my cast is the worst I still catch fish. I cast the best when there’s a good breeze behind me and often only cast the length of the head usually delivering it in one false cast from picking up a bit of line on the water to load it hen a false cast back and then it delivers. On calm conditions I usually don’t like fishing in then as I find it hard as I find it harder to present the fly. The line sometimes splashed down and when I’m false casting I try my best but after two false casts the line feels heavy and I sometimes lose control and the cast just crashes down. The line was a present, Rio Grande. From the sounds of it it may be over lined and it maybe an 8 instead of a 7 hence why I think the line feels heavy after a couple of false casts. I apologise if I haven’t been very clear and ask away If you need any further information to diagnose the possible issue.