Provided are, among other things, systems, methods, apparatuses and techniques for generating energy from water current. According to one representative embodiment, an apparatus includes: a paddlewheel having multiple individual paddles, an axis of rotation, a front side that is forward of the axis of rotation, and a rear side that is behind the axis of rotation; and a covering structure having a front portion that (a) covers a first part of the front side of the paddlewheel, leaving a second part of the front side of the paddlewheel uncovered by said front portion and (b) extends a distance forward of the front side of the paddlewheel, with the front portion of the covering structure being tapered, becoming thinner as it extends further forward of the paddlewheel.