What ever happened to Cargo Submarines?

They’re very popular for drug smuggling.

I knew the economics of a cargo submarine would be pretty bad But the concept is so fun and interesting, and probably so useful in its niches that I want to see one. Even if its only like 1 giant sub, it would just be fascinating to see.

That thumbnail brought back so many memories as a kid. There was this book I loved growing up that had all these 1950s to 1980s ideas of what the future would have and the picture of the cargo sub in the Thumbnail was one in the series of the Cargosub's entry.

While there may theoretically be applications for bypassing ice, the increased submaritime traffic could increase global tension. Especially that idea of retrofitting Typhoon class subs. First objective is to make them a lot more observable so there aren't collisions or allegations of using civilian* vessels for surveillance or other geopolitical gambits.

Submarine tankers were seriously considered as an alternative to the Alaska Pipeline. Also, Frank Herbert wrote a story about undersea "tug subs" that pulled oil around in gigantic blimp-like bags.

That WWI German sub actually made at least one run and delivered a load of mail from Germany to US. The postmarks are very collectible

As a commercial diver, the deep ocean is scary enough sometimes. Only been in one sub. Props to the sub guys, they’re very brave.

We all live in a yellow submarine,yellow submarine,yellow submarine.

The Germans transported a few items to Japan during WW2 by submarine. They also failed to transport some items because two of the subs were sunk. I gotta say that I do find it surprising that they didn't carry through on plans to obtain industrially important metals by submarine. They had plans to get them from South America, and IIRC they actually bought some of the metals. The metals were needed in relatively small amounts, and a submarine would have been practical. Of course, with the cracking of the enigma codes, the Allies would probably have gotten the details and stopped it. I think that was how the subs bound for Japan were sunk. Ultimately, cargo submarines are only useful in desperation, and unlikely to effect the outcome of a war. But I would bet the nurses evacuated from "Corridor" Island (Corregidor) were grateful for the use of regular subs as passenger subs. Can't help but wonder how many cargo subs would have been needed to maintain the forces on the Bataan peninsula. Losses would have been very high from IJN anti-submarine action.

There is one advantage subs have over surface ships too that I feel is worth mentioning. That is weather resistance, big cargo ships need to chart their courses with weather in mind, avoiding heavy weather systems or charting courses where they don't need to fight the wind. A cargo submarine encountering heavy weather can just dive and continue on unaffected, especially if it is a nuclear sub that doesn't need to rely on batteries when submerged. Once more commercially viable nuclear technology becomes a valuable business model, such as the advent of SMR tech that can open the window for nuclear commercial ships, then its possible that cargo subs could become viable, but only for one specific type of cargo imho, and that would be cargo that is both high priority and ultra heavy. Heavy cargo in general can be handled by current types of cargo vessels, and priority cargo can typically be transported by plane. But cargo that is both can be tricky to transport economically, and that is a niche that a cargo sub could fill.

I think there are some niches - namely cargo that's low volume and heavy, or going places with a lot of storm activity - where the concept still makes some sense.

i can only imagine how much of a pain a cargo sub would be to get though straits channels or canals or how few harbors would be deep enough for a large cargo sub to dock at.

yellow submarine submarines may not work economicly but what about semi submersibles?

A correction: The German WW1 cargo submarines were not U-Boats (i.e. combat submarines) with the torpedo tubes removed. They were purpose-built as cargo vessels. It was in fact the other way 'round. After the souring of relations with the US and its entry into the war, the cargo submarines, freshly out of a purpose, were converted to combat submarines. Specifically, their large size and impressive endurance were taken advantage of to convert them into the first long-range "cruiser" type submarines, intended to operate as far as the US East coast.

Correction 2:07 it is corregidor island not corridor island. Corregidor came from the spanish word corregir meaning to correct. Corregidor island means the corrector's island as it was used by the spanish in their customs sytem where ships entering manila would need to stop at corregidor to have documents check and "corrected".

I'm glad you found and explained these concepts to us

Barracuda class submarines were not cargo carriers. They were smaller and slower than the traditional fleet boats used by the US Navy during WWII, and were intended specifically to hunt other submarines using newly developed sonar and guided torpedoes (the conspicuous bulge on top of the bow that looks like a shorter second conning tower is a housing for sonar). They didn't work very well for that either, and were taken out of service relatively quickly.

Actually, the real reason why there is no cargo subs and there will never be (at industrial scale I mean) is because of physics. A submarine needs to have the same average density as the seawater it is sailing in (1.026). Cargo in a container has a much lower density (remember: containers float). So a cargo submarine would need a huge amount of fixed ballast (typically lead) to keep it underwater and prevent the submarine to float. To get an idea, look at a filled container ship and imagine how much lead ballast you would need to add to drown the ship. That's the amount you will physically need to put in a submarine of the same size. No wonder it doesn't exist and never will.

In the 80s, pop mech had a cover story related to giant oil tanker subs that were very cool looking. I immediately built a large model of one out of legos.

What if it were smaller scale? Like a single cargo container. Perhaps for short distances, or to small islands. Would it be possible to have them in a train like set up?