I think they're bloody useless I'm afraid. maybe I'm cack-handed but whenever I try to use them my foot (and the rope or webbing they're on) simply shoots straight underneath the boat. They're a little bit better if the thing lies flat against the hull but it's nigh impossible to get your foot in the next rung as the weight on it means it's about 3" wide and right up against the hull somewhere. With a RIB all I need is a grip somewhere just inside the tubes and the ability to submerge myself a bit to get a "run up". As I bounce up I just flop onto my stomach more or less on top of the tube and half roll, half walrus style waddle, into an undignified heap into the boat. Works with or without a buoyancy aid on for me.