I just tried my turbo fins for the first time on the Amelia River in the Adventure. It was great. I will really feel in shape when I get used to these pedals i.e.- when they feel fairly easy. The normal pedals are too easy and these are another level of difficulty, but the performance is great. You can really cover distance with these and you feel like you've exercised. The big surprise is the way it turns now in combination with my larger sailing rudder. Much tighter radius and response!
I had my GPS on and I almost couldn't go slower than 4 mph. 5 mph was fairly easy. I was in a lot of current and chop and the additional power seemed to give me more confidence, but I still need to make an adjustment (get stronger) to these before I feel at "one with the machine." The use of the thigh muscles is a great cardio work out. I've read that the veins in our legs have check valves (to keep the blood from falling down onto out feet)and when you pump your thighs your veins actually help your heart pump blood through out your body... sort of like giving yourself CPR while pedaling.
There is an article in the current Discover magazine in which an evolutionary biologist claims that since we can out-run all land mammals in endurance over distance including horses, giraffes and wolves...in other words these other species can easily beat us in sprints and over a few miles but can't run marathons. He says that was an adaptation that we have evolved which helps us pursue prey. One of the traits which allows us to do that is lack of fur and lots of sweat glands. We don't overheat and we are more efficient over long distance... we are designed to use our legs to cover distances more so than even herd animals. That's one theory...seems like it could be right. I know I want to use the turbo fins to cover distance and I think as I get into touring more I will be VERY competetive with fast paddlers. Looking forward to the 4 day trip on the Suwannee River in 10 days with my new propulsion system. I think the paddlers I'm going with will be quite envious after a few days around the turbo Adventure. This weekend I will try them on flat water in a lake to measure top end speed and have a few more hours to get myself broken in to go on the longer trip where we'll be doing at least 20 miles per day.