Related, CD-Rs. When I left my submarine in 2013, they (by which I mean the entire Virginia class) were still using them to store archived logs, despite my explanation that they’d be lucky to get a decade out of them. The first chosen storage location was literally the hottest part of the engine room, right in between the main engines. Easily 120+ F at all times. After protest, we moved ours to a somewhat cooler location. Still hot, and still with atmospheric oil and other fun chemicals floating around.
I look forward to the first time logs from a few decades ago are required, and the media is absolutely dead.
EDIT: they weren’t even Azo dye, they were phthalocyanine. A decade was probably generous.
I was curious how some of the more wealthy yacht owners solved the marine puzzle. What kind of computer would they use? What kind of parts would go in? What would a basic system cost? So I asked one, he opened up a compartment with a stack of cheap Acer laptops vacuum sealed in bags. They last 2 to 6 months, when they stop working he throws them away. The sealed one has everything installed, a full battery and will sync as soon as internet becomes available. When plugged into something the new laptop is never the problem. He spend a small fortune arriving at this solution.
Looked at doing this on a moderate sized yacht, before decent chartplotters were reasonably priced. We wanted to have a decent spec PC drive a chartplotter at the helm, nav table, TV in the living area. To build a PC that would survive was near impossible for a performant system. We were looking at fanless sealed industrial machines.
Everything. Someone could bring a lawsuit up years later, and logs would be necessary to determine if they had standing.
The aforementioned optical media storage was specific to the nuclear reactor and electric plant; I think everyone else’s were stored differently. Not positive.
EDIT: sibling comment below mentions performance data. Yes, that too. I graphed (nuclear) fuel consumption on one underway, and was surprised to find it didn’t match expected. My Captain was also surprised, and thrilled, because it meant he got to be more important (fair enough; who doesn’t want to be listened to by their boss?)
> Knowing nothing of submarines or seafaring, I'm genuinely curious as to what is logged on a ship that may be necessary a decade later?
I noted in another comment that the National Archives say only "deck logs" are retained permanently, and it looks like this site lists what they contain: https://www.history.navy.mil/content/history/nhhc/research/a..., which includes all kinds of things.
Stuff like "Actions [combat]", "Appearances of Sea/Atmosphere/Unusual Objects", "Incidents at Sea", "Movement Orders", "Ship's Behavior [under different weather/sea conditions]", "Sightings [other ships; landfall; dangers to navigation]" seem like they'd be useful for history and other kinds of research.
Stuff like "Arrests/Suspensions", "Courts-Martial/Captain's Masts", "Deaths" seem like the kind of legal records that are typically kept permanently.
Stuff like "Soundings [depth of water]" were probably historically useful for map-making.
Good question. As far as I'm aware, outside of a few special circumstances (like birth records), the vast majority of legal record preservation requirements are seven years with some being as long as ten years. Of course, with the service life of some military ships and aircraft now being stretched >30-40 years, I can imagine it might be useful to have records of component failures and replacements, especially for statistical modeling.
In the case of a ship (or sub), I'd assume that they'd rotate optical media archives off the vessel every year or two and transfer them to some central database. After all, a vessel can be lost and the data is also useful in the aggregate.
> outside of a few special circumstances (like birth records)
Also IIRC several US states require medical record retention for minors of up to one year past whenever they become adults, so that's a potential 19 years there.
No idea what they actually log but it seems like performance data from the propulsion system under a wide range of conditions would be useful when designing the next generation of such systems.
I look forward to the first time logs from a few decades ago are required, and the media is absolutely dead.
EDIT: they weren’t even Azo dye, they were phthalocyanine. A decade was probably generous.