I use large "diver" style fins and cannot for the life of me understand why so many tubers use the silly little half sized, semi useless "float tube" fins
Caddisfisher, if you didn't set sail in something as big as a bouncy castle then you'd be able to use smaller fins!
You have a point right enough and I guess it's horses for courses. I find the 'girly tubing fins' adequate in most smaller water or gentle breeze situations but have seen the benefit of divers fins in more difficult conditions, granted.
I use the 'arm aching' Shakey which you know sits low in the water and therefore is affected less by wind and with the V shape should be easier to propell than the U shaped competitors.
Fishing weedy waters may also have a bearing on the size of fin used.
You are right to bring this up, as using (or at least having the option of) big fins might be easier on a sailor who may have knee problems.
You also mentioned a "slower more powerful kick" which maybe is more to the heart of the issue as I tried a variety of techniques of turning, steering, motoring, etc. when I started out and one concern I had was the possibility of inducing cramp in the calf if an overpowered erratic paddle was adopted.
Conclusion:- I agree that larger fins along with some form of neoprene boot is well worth a try or investment if a loch of any size is to be tackled, if you have any knee issues they may help in achieving a decent output whilst being more sympathetic on the patellas, if you are walking any distance to a hill loch where the combined weight of the standard 'hard' fins and boots MAY be an issue.
For the average tuber I think the 'walter softy' of fins will be adequate.
I know the tubers on this site have their own preferences as to their kit and this is
just a generalisationMaybe see you afloat sometime - how will I know you? is your tube distinctive in any way?
Iain