4 ms·

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?

Mountain_Skies 2y ago
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.
sgarland 2y ago
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?)
- bushbaba 2y ago
  If lawsuit related. Maybe they wanted the backups to fail?
tivert 2y ago
> 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/archives/Collections/deck-logs/what-is-a-deck-log.html 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.
mrandish 2y ago
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.
- Terr_ 2y ago
  > 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. But otherwise it's usually seven-ish.

Mountain_Skies 2y ago

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.

sgarland 2y ago

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?)

bushbaba 2y ago
If lawsuit related. Maybe they wanted the backups to fail?

tivert 2y ago

> 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/archives/Collections/deck-logs/what-is-a-deck-log.html 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.

mrandish 2y ago

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.

Terr_ 2y ago
> 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. But otherwise it's usually seven-ish.