Oldport Shipbuilding Co. was in dire straits by the mid-19th century, its major contracts for naval arms lured away by competitors and its bread and butter of Nantucket whaleships gradually dwindling away.

Many companies would have folded under the pressure, but OSC decided to embrace innovation. It was able to secure a contract from Lesbos Fisheries Supply Ltd. for a fleet of fishery support ships that would use new technologies to freeze whales and fish as they were hauled in by trawlers, allowing for fewer costly trips to port. Rather than simply construct simple ships, OSC decided to dazzle their investors with something new.

Using steam engines sourced from surplus Royal Navy ships laid up after the end of the Crimean War, OSC employed Irishman John Philip Holland to encase them in submersible, watertight, and fusiform hulls. Holland’s design drew inspiration from mako sharks, and substituted a jointed metal fin for a screw propeller. Norwegian explosive harpoons built into the vessels served to incapacitate larger prey, while a series of deployable trawling nets could be used for smaller fish. Either way, the captured sea creatures would be fedd into a series of whirling processing blades (which, when locked together, doubled as watertight doors for the bow).

OSC also contracted Charles Babbage to produce a series of sophisticated difference engines to control the ships; Babbage’s design was capable of following a number of simple commands and had the ability to re-coal itself from suitable stocks. The refrigeration plants were of a revolutionary design by Carl von Linde, early prototypes of iceless systems that would come to dominate commercial iceboxes for the next 50 years.

Both Holland and Babbage left the project disillusioned by its rather crass commercial nature, but that didn’t keep OSC from manufacturing 100 of its “Shark-Class Autonomous Boats” or SCABs. The latter acronym was particularly pertinent as the fishermen and whalers based nearby feared that those boats would drive them out of a job. The SCABs underwent a series of spectacularly successful shakedown cruises, returning enough product to pay for their development and construction.

However, Lesbos Fisheries Supply–pressured by sailors–insisted that OSC had not delivered what had been asked of them and refused to pay for the SCABs or accept delivery. The breakout of the American Civil War also meant that OSC had to clear its slipways and harbor for a sudden influx of naval contracts. This led OSC management, unable to find a buyer for a product well ahead of its time, to simply remove the part of Babbage’s mechanism that ordered the craft to return to base. They would, it was thought, simply fish until their stocks of coal were exhausted and then sink.

Such was not in fact the case. Babbage’s innovative difference engines and Holland’s revolutionary design meant that the SCABs continued working unabated for many years. They simply dumped excess product when their holds were full or accepted coal as payment for the fresh fish they had caught. This led to them becoming a notorious navigation hazard as the difference engines powering them began to break down, and SCAB attacks were a fact of life for oceangoing vessels as late as the 1940s, with unconfirmed reports of attacks as late as 1996.

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