Paddle boats have a rudder system to steer them, the expensive ones have a steering wheel, the cheaper ones have a steering handle in the middle - both devices turn a "fin" in the back of the boat to the left or right.
You have to be in pretty good shape to be able to manage a paddle boat alone. When my daughter was 12, her and I went out on a (4 seat) paddle boat. We had not problem getting out to the middle of the lake. It was a huge problem going against the current to get back to shore. It took us 30 minutes to get to the middle of the lake and an hour and a half to get back to shore. We were both so tired, I was looking for another boater to pull us in but none would stop when they went by. We ended up having to take turns peddling - so only one of us was peddling at a time (an no we didn't just sit there and go in circles).
It has been said that some of the residents along the lake have paddle boats. It is possible that a kid took one of those boats out and was not able to get it back to his residence so (s)he asked the girls to help. The girls drop their bikes, put the purse on the other side of the fence so no one would take it and get on the boat to help peddle it back. Once the boat is back, the girls would start walking back around the path to get their bikes/purse. Perhaps they met with the abductor as they walked back around to get their bikes. So maybe the place the girls were taken from isn't where the bikes were left, but somewhere off the road on the other side of the lake.
Maybe the paddle boat person isn't coming forward because they are a kid that wasn't supposed to be on the boat - the kid wouldn't want to come forward for fear of getting in trouble by their parents and it would be pretty scarey to be a kid and find yourself innocently thrown into this mess. However, if something like that happened, the paddle boat person may very well have seen something or at least seen which way the girls were walking when they went back to their bikes.
moo