If I remember, the diagram shows them mounted on top of the transom. But, on my H23, I couldn't get the correct angles because the top of the transom is too narrow. So, I mounted them vertically on the inside wall of the stern. I posted a picture last year - should be in the archives. There is an optimum up-down orientation to get maximum holding power, but I can't remember which way it was without looking. Anyway, if you mounted them "upside down," you would simply unscrew them and turn them around.