I had first asked about the BWY ladder in another thread, Terry gave a full description of it and I've pasted his comments below. As it turns out the BWY ladder is for use with low docks (even at low tide most docks here are still at least 2' above water), and not really a swim ladder since the first step doesn't reach the water. I've asked Cheryl at BWY if they would sell just the Genoa cars but so far they have declined.
James, with this setup the force applied to the tracks should be somewhere between straight down and horizontal, not sure how a backing plate would come into play. Please let me know if I'm wrong, I don't want to screw anything up.
Terry, I would be interested in a close look at the ladder so I'll PM my email address to you. Perhaps a mod to extend the ladder is the ticket. But, I really like the look of Scott Vos's ladder posted in his mod.
Response from Terry copied from other thread
Yes I have noticed it is not listed, but they do have it and sell it. Funny thing is I saw a manufacturers sticker on the underside and see it is made here in Vernon, B.C. and shipped to BWY where they put the genoa cars on it. It now retails for $250.00 but was $150.00 when I bought it two years ago. It is solid SS with heavy plastic steps and holds my 220# easily. My wife insisted on it for her short legs while at the slip. It would easily hold you with scuba gear but I am not sure it extends down low enough to the water level to reach, it only has two steps and extends maybe a foot below the rub rail, perhaps if you got a short extension for it. It is great for side entry at the docks but I don't see it being a swim ladder.
On Edit: OK curiosity won, I went out to the garage and retrieved it, it is definitely heavy duty. The top step is SS tubing with two round plates welded on it to bolt the hard thick plastic step on. The bottom plastic non-skid step is bolted onto a 3" X 14" SS plate that is welded to the side SS tubes. Now, there is 1.25 inches of exposed SS plate on each side of the plastic step where one could drill a couple holes for attaching a removeable extension, I say removeable because you want the ladder to do double duty both as a slip ladder and swim ladder when diving. Alternatively perhaps BWY would sell just the cars with quick pins, one is taller than the other to keep the ladder paralllel while mounted on the not so parallel track. They may or may not be compatible with a WM ladder. I can send you a pic with an e-mail address but I don't do pics here, too onerous.