The older than you , is between 1892 and 1900, looks more 1892, reason, the Royal Engineers were remodelling the fort, and had removed all the guns and had not yet worked on the walls or removed the old gun positions and the gun tower at the rear of the fort is there also the gun slots in the front wall haven't been blocked up by the west tower.
But then it looks like a painting, so artistic licence leaving the guns out but the ship is a steamer.
I have seen lots of postcards with bits added, one is a liner sailing between the fort and the shore. I have a pic somewhere, hopefully it will turn up. The water would have not been deep enough, I wouldn`t sail a ferry boat between the fort and the shore and they are flat bottomed.
Seen a jet go between the fort and the lighthouse even a couple of seals messing about over that stone abortion runs from the fort past the light, that thing is damaging the fort walls, concentrating the tide directly into the walls, the google map of the fort gives a better idea of what I mean.
Have you any close up pictures of the fort, especially the top of the glacis, I don't go to the place anymore but it still interests me.