I would say the deepest part to be treated wouldn't be more than 6'. So probably 3' depth could be used. I'm going to add some additional dye soon which I expect to help prevent future growth and that depth could become less. I could also rake it to remove a lot of the weeds, but I don't think it will get the roots. Should I apply the treatment first and wait for it to begin dying before I rake?

As for the boat, my wife doesn't care for the look of having a john boat on our beach. Our lake is new enough that it isn't even full yet. It is going on the third year of filling, so it's quite slow.

If I spray on the surface of the water instead of injecting, that won't be nearly as effective, correct? I could use an inflatable boat or our floating foam raft too and just hold the spray wand down below the surface. Seems like there may be a science to this. Thanks for talking me through it.