Military Transport Submarines Make Sense

Unlike Ukraine—with porous borders ripe for foreign weapons shipments and aid—Taiwan will be “very hard to arm” during a conflict, says Blake Herzinger, a Pacific security expert. The island sits about 100 miles east of China and is within range of its missiles—along with U.S. forces that would presumably respond from Japan and elsewhere in Asia.

From the Ruck. 

One solution to this problem could be a military transport submarine.

Submarines aren't immune to anti-submarine warfare tactics, but it is much, much harder to sink a submarine than it is to sink a lightly armed military transport ship and is only marginally slower. The fastest submarine ever built, the Soviet K-222 had a top speed of 51 miles per hour. A speed of 23 miles per hour traveling nearly silently, or 40 miles per hour at the expense of stealth, would be more common.

A submarine can be built to be 10,000 to 20,000 tons (only a portion of which can carry cargo, of course), which while smaller than a commercial freighter, can carry vastly more cargo than a C-130 (about 20 tons), or a C-17 (about 80 tons with a much longer range). I've previously considered the idea here. Historically, capacities of 95-800 tons have been used in practice, although cargo in the tens of thousands of tons are well within the reach of current level technology. Colombian drug cartel submarines can carry about 200 tons. Well developed designs for cargo submarines carrying 6,000 to 11,000 tons of cargo have been serious considered in the past.

The idea isn't entirely conceptual either. The Russian merchant marine has built some nuclear powered transport submarines to deliver freight under the ice pack on the Arctic Ocean.

The basic concept is that the military frequently would like to have the capacity to supply substantial amounts of supplies and equipment by surprise or in blockaded coastal areas.

This could be smuggling supplies to a friendly nation, like Taiwan. This could be delivering supplies in support of a hostile D-day style invasion force. This could also create a capacity to evacuate civilians, injured soldiers, or soldiers who need to be rotated out of a combat zone, away from an interdicted area.

It wouldn't be cheap, but if one used an air independent propulsion diesel-electric power supply, designed it to withstand depths more shallow that nuclear attack submarines and ballistic missile submarines, and the cargo submarine was only minimally armed, it would also probably be cheaper than a nuclear attack submarine.