1. Field of the Invention
The present invention relates to rope ladders.
2. Description of Related Art
Ladders that have flexible stiles—colloquially “rope ladders” or in nautical usage “pilot ladders”—are better suited to certain applications than are ladders that have rigid stiles.
Rope ladders are particularly well adapted for: (a) compact storage between uses; (b) suspension, including from great height, and (c) conformance around surfaces. Thus, for example, rope ladders may be well suited for escaping from buildings, climbing into rescue helicopters, and embarking on or disembarking from large ships.
Conventional rope ladders do however present challenges; perhaps most significantly, they can be very precarious. When ascending or descending one, a user typically grasps the stiles on either side of the rungs. Problematically, although a line of force runs vertically through each stile above the point grasped, the line of force below the point grasped is redirected by the user's lower body as his legs drive the supporting rung forward. This effect can leave the user in an inverse position, with his back to the ground.
Furthermore, if one of the user's hands loses its grip on a stile, both the user and the conventional rope ladder are likely to twist away from each other, further raising the risk that the user will fall.
Additionally, when using a conventional rope ladder, it is possible for a user's hands to become pinched between the rungs and a hard surface adjacent the ladder, for example a ship or a building. Alternatively, where the adjacent surface is soft, for example the gunwale of an inflatable rubber watercraft, a conventional rope ladder may become enveloped and thereby inaccessible.
Finally, a conventional rope ladder is challenging to mount for descent, for example from a high-rise building roof or window or from a buffeted vessel such as a ship or helicopter. A user has to swing his weight backwards out over the top of the ladder and then reach down with his legs to feel for the closest rung, precariously shifting more weight outside until—hopefully—his foot securely finds a rung.
Accordingly, what is needed is a rope ladder that addresses these challenges.