|User||Any vessel not powered by sail|
A gastrine is a biologue which functions as the engine for any vessel not powered by sail. They turn the screws, or propellers, that propel the vessels like rams and cargoes. Each one consists of a large wooden metal-bound box that contains gastorids, large muscle-like organs, that have been grown about a metal section of treadle-shaft or shaft-section that is also inside the box.
On a vessel, the gastrines are arranged in rows on the organ deck, each shaft-section connecting by great pins to form a whole treadle-shaft that runs the vessel's length. To operate, the gastrines' muscles are stimulated by limbers, which gets them initially moving. Once they gain enough momentum, they push and pull the treadle-shaft on their own, turning the gears and ultimately the screws.The application of gastrine power is a complex affair: lines of gastrines (and their accompanying limbers), arranged in "gastrine pulls" or "pulls", are attached to dog-boxes, or sets of gears and great levers. This structure allows a ship's gastrineer to precisely control a pull's power and where it applied. The power of a ship's pulls can be applied to one screw, two screws, or, on the largest vessels, even three. Gastrines make almost no noise while working; as a gastrine vessel such as a ram passes by, someone would hear the hiss of parting water running down the length of the ship, and feel a faint pounding or throbbing through their body and the surrounding air. A vessel under gastrine power is referred to as "treading" (past tense "trod"), as opposed to the sailing of sailers. An anchored vessel will usually keep its gastrines slowly treading over, without an engaged screw, in preparation for a quick start following danger or impelling news.
The gastorids used in gastrines are grown by viscautorists, who specialize in the creation of biologues. Starting from basic living matter, they are raised inside empty gastrine boxes. Each box contains wooden protrusions called bones, which the gastorids attach to and used as anchor- and leverage points. A gastrine is "fully grown" when the box and the muscles form a complete organ, the opening of which is tantamount to surgery. Fully grown gastrines are taken from test-mills, or "laboratory-factories", where they are grown, to dockyards to be installed on the organ decks of waiting vessels. Each gastrine's shaft-section is attached to its neighbor's, integrating them all into the pull.
Gastrines, like the ships they move, are usually referred to as "she" or "her." Each day, the gastrines are fed a series of "meals" through special chutes and hatches in the form of nutritious pabulum soup. The waste from these "meals" is expelled by the gastrines into a sluice-way beneath each pull, which in turn carries the waste to the bilge to be expelled to the sea. Organ decks, between all the pabulum and waste, often smell like butcher shops, and nadderers, fond of the taste of the muscles within the gastrines, are attracted to the expelled grime and discharge that trails in a gastrine vessel's wake. A large portion of a vessel's crew is assigned to caring for the gastrines, their limbers, and the mechanisms of the pull. Gastrines and their accompaniments actually have precedence over the crew in terms of food and care, since crew becomes irrelevant on an immobile ship.
Gastrines, being biologues, eventually die for various reasons, including old age, disease, or damage sustained in a fight or storm. When a gastrine dies, it can sometimes seize up, interfering with or even halting the movement of the screw, an event known as clearing. When this happens, the gastrineer's mates, utilizing great axes hanging from the walls, have to break into the gastrine box and hack the rigid muscles away from their shaft-section, allowing the treadle-shaft free movement again. This obviously destroys the gastrine, necessitating its swift replacement. While replacing an entire pull is often the best course, of action, this is costly in time and money, making single-gastrine replacement far more common. If a single gastrine is replaced, its pull neighbors behave slugglishly for a time for unknown reasons. Gastrines can live a maximum of twenty years, if they have even steady lives, such as working a cromster. A drag-mauler on the vinegar seas, on the other hand, with its speeding up, slowing down, stopping, ramming, enduring gigantic waves, and absorbing the shocks of cannon balls and nadderer attacks, will work a gastrine hard enough that it must be replaced in about five years.