And while the hinge is readily available, I couldn't find a suitable "locking sleeve." No doubt I should just contact a SS guy and let their knowledge be the guide.
I will look into letting the bottom of the ladder be the top rail too... that may actually work. The ladder is very nice, well stood off so that the angle of the transom is taken into account, but climbing that top rail while wet and slippery and having little to hang onto is a risky business.
Also (jokingly) being able to open that top rail right there gives me a "proper place" to "go" over the side. GRIN