A boat lift is attached to piles driven into the earth or to another object. The boat lift is held in horizontal position relative to piles or the object to which it is attached, but vertical movement of the boat lift relative to the object is permitted. The boat lift is connected to the piles by modular units or cube constructs that have a post extending there through. The post has a blade extending from it. The blades are attached at an angle, according to the application, to pile guides that engage piles. The pile guides vertically traverse the piles, permitting the boat lift to move vertically relative to the object, but fixing the horizontal position of the boat lift.