You are probably right about the "add ons" to the original structure I never checked that on the original plans while I was on board. I never really saw the point of the bottle screw. The jib was sitting in a crutch and the crane was hydraulically operated, so with the power off, the hoisting and slewing valves would be closed, hydraulically locking everything in place.
I suspect that a smaller rope for securing the crane hook would have broken before the safety valves lifted on the hoist winch, and that is why they were using the old mooring rope.
I was never a "Monkey see, monkey do" Engineer, I always try to look at first priciples and the Instruction Manuals for the truth, what other people do, and what has "always been done" etc should only be for initial guidance, but a lot of people never look at the underlying Engineering principles or read the manuals.
You mentioned the Portholes. lots of them leaked when it rained, margarine and ice cream tubs in the Port boxes to catch the water. One of the Superintendants Inspection Reports told the Chief Officer to order and fit new rubber seals to the Ports.
The Chief Officer decided it would be easier to cover the outsides with Silicon Sealant and paint over them. He didn't clean the paintwork first so the Silicon didn't stick properly and they all still leaked. He couldn't understand why the screw heads on the internal glass retaining plates were popping.
I had to explain to him that water was leaking between the glass and the metal frame, the frame was corroding, the rust had a bigger volume than the original steel, and the expansion was forcing the glass into the ship and popping the heads of the screws.
The Port openings also had a problem with rust build up underneath the seals between the fixed frames and the opening frame.
The solution is to unscrew all the screws, remove the glass, chip and scrape the frame back to bare metal, treat it with Phosphoric Acid (Rust converting primer/ Metalbrite HD), to prevent any future corrosion and put the glass back, the old fashioned way, with putty, because the corrosion damage would prevent a rubber seal being effective.
Any damage to the opening Port sealing faces could be similarly treated, then made good with Plastic Steel, before new rubbers were fitted.
The Chief Officer preferred to keep putting more layers of Silicon Sealant over everything, even after I pointed out that the opening Ports (especially the main Deck ones) were also Emergency Exits and it was not a good idea to have several inches of alternating layers of Silicon Sealant and paint plastered over them.
Rust is often a good way to find cracks on Deck, it acts like a slow acting Penetrant Dye Kit!
It is always better to ask a stupid question than to do a stupid thing.