Since you still have them, when is the last time you took them out and used them?
I never used them after high school or college, except I think we messed around with them a few years ago. Like I said in the old link, it was really hard to keep your legs from splaying outwards. It may have worked better in still water, but the Sound isn't usually that calm.
I used them with two short raft oars, but they might work better with a kayak or standup paddle. The flaps never really worked because they didn't drop down enough to catch water when you pushed back, so I used the oars. If you lashed them together and used a standup paddle, that might be best of all, but at that point you're basically just paddling a horrible standup board.
Best thing is being out there in the same place doing standup, saying hello to some of the same people sitting on their decks who remember me out there on my weird aqua shoes in the 70s.