http://www.outcastboats.com/outcast/products/accessories.aspx?cat=15&id=280

I fished the lake today and tried a new set of outcast fins as linked above. They are designed to be used with either a wading shoe or boot foot waders, which I wore today. As you can see in the link, the fins come with 2 adjustable straps and a non adjustable rubber heel sling. One of the adjustable straps is for retaining purposes and attaches around your ankle to keep from loosing the fin in case it parts ways with your foot. The other adjustable strap goes over the top of your boot and with the heel strap, securs the fin to your boot.  I needed to adjust the throw on the top strap slightly to snug them down over the top of my boot , which was an easy adjustment. While the heel strap was fairly tight, it would have been nice to have some means of adjustment to make it tighter.  In my previous experiences with a float tube I have used scuba diving fins over stocking foot waders without using a boot. I've never used an ankle strap with them and they have never come loose. The top straps on the Outcast fins loosened up over time, enough for me to notice but not worry. The total time on the water was roughly 4 hours.

The wind was blowing easily 5-10mph with frequent stronger gusts that made paddling against it rather difficult. Rounding the tip of a small island on the main lake body side presented a challenge to keep from being blown out to open water but was doable for an out of shape old guy. As I type this, it is an Advil moment. To make a more effecient kick I was required to lean forward on my float tube,  Not doing so, resulted in wasted effort in the form of splash  My only other option was to minimize the stroke length. 

Performance wise, the Outcast fins were dismal compared to the scuba fins. My 15 year old son was with me in an identical float tube,  using my older scuba fins and had little trouble with the wind. Only a few leg kicks would keep him on pace with my 10.  I feel that the stiffness of the outcast fins, in congunction with less surface area to push against the water due to the use of a boot is the main deterent.

Given a choice, with stocking foot waders,  I would prefer to use a pair of scuba dive fins over the outcast.  With that being said, the outcast fins work as advertised with a boot foot pair of waders.  The outcasts work, but you have to work harder to use them.