I emailed the new owner in Denmark
( or some place). He told me the same thing. Want a boat ladder? We can not help. No intent to sell them anymore. He had a very few left in stock he would sell, but would prodipuce no more.
They will continue to all dock
ladders. Maybe you could buy a dock
ladder and modify it to work. Go figure.
The difference is the boat ladders had a kind of extension on the rungs making flats for your feet, the dock ladders don't have that feature. Also the boat ladders had a little push off to keep the ladder off the side.
If you can weld stainless you might have a shot.