...and it definitely included those waters... The boundary was defined by a straight line leaving Mauritius to port, then straight up to the entrance to the Persian Gulf, which places the Cargados Carajos roughly 100 NM within the permitted route...

Not sure what you mean by "doubling down" on their nav systems or procedures, but I doubt that's the required 'solution'... I think a bit of 'reverting' to long-established/classic principles of navigation is what will most likely insure against a repetition of such an incident... Ken J said it best, in his post in the earlier thread below:

New Incident, Old Mistake...

A large majority of grounding and other ship loss incidents that we studied or investigated in the Navy in the "pre-chartplotter" days turned out to be caused by the familiar "failure to keep a proper DR" problem.

In other, simpler, terms, no one bothered to check the road ahead for potholes and detours. The reason large area paper charts were physically big was so a navigator could lay out his entire track from departure to arrival that would show possible hazards like islands and reefs enroute. Scaling limitations make this unreliable on a chartplotter.

Certainly, the maintenance of a DR plot on paper seems hopelessly 'Old School' aboard a VOR raceboat... And yet, in my estimation, nothing else so could have so easily prevented this sort of mishap, and forced the navigator to see the forest for the trees... The simple, time-honored routine of plotting one's Noon-to Noon runs on a chart of the Indian Ocean (or perhaps every 12 hours, aboard boats sailing at such speeds) would have served to gotten the navigator's head out of the game of weather analysis, and tactics, and forced him to see AT A GLANCE their relative position to a clearly marked danger that lay ahead... There is no doubt in my mind that this grounding would have been highly unlikely, if such a basic, elemental navigational procedure had been followed... Unless, of course, the navigator had been so deeply fatigued to the extent that he simply was not capable of seeing, or thinking, clearly...

In trying to assess how something so seemingly inexplicable could have occurred, one thing comes to mind... Sure, this might be grasping at straws in search of contributing factor, but I can't shake the notion of the rather odd naming of this archipelago as the Cargados Carajos SHOAL...

This archipelago is a vast cluster of drying reefs and islands - at least one of them minimally inhabited... Hardly what most of us normally consider to be "shoals", akin to places like Nantucket, Diamond, Frying Pan, Canaveral which are labeled as such... And, which can often be sailed OVER, at least in some places, in benign conditions... I can't help but wonder, that in a preliminary, cursory scan of the e-charts of that area, their designation as being only a "shoal" might have - if only on some subconscious level - contributed to their being filed away in the navigator's memory bank as not necessarily posing a REAL hazard that required a closer look, or pinning as an atoll or island group would have... And, perhaps prevented him at that moment, from hitting the "+", or "Zoom" key one more time...

Look at the pic below, which is a C-Map chart of the area at a certain level of zoom... 2 things are very odd about this view...

First, the Nazareth Bank to the north of the Cargados is exactly that, simply a "bank"... A vast underwater plateau of comparatively shoal water, no portion of which rises above the surface... And yet, a number of "Obstructions" are charted, and indicated...

However, at the same time, down in the Cargados archipelago - which features several islands, and even a lighthouse on Ile du Sud adjacent to the scene of the grounding - there is NOTHING indicated to suggest that area is nothing more there than "shoals"...

In addition, notice how along a line thru the lower portion of the Nazareth Bank, the chart display becomes "quilted", likely the result of a single chart view showing 2 different resolutions as the result of a duplication of 'original charts' of different scales...

Again, I'm probably grasping at straws, here... But what was most striking to me, was the audio from the latest video, where the skipper is clearly heard to say "We're sailing over some SHOALS now, 40 meters..." Would that sort of cavalier acceptance of meeting with such shallow depths in the middle of an ocean, in the tropics, have been on display if that place might have simply been named "Cargados Carajos REEF", instead?