Flood Ballasts

While Seaglass permits a ship the ability to survive beneath the waves. The ballast allows the ship to reach it there.

— A Treastise on Submersible Navigation Within The Great and Bottomless Ocean

Flood Ballasts are specialized compartments built into the lowest portion of a vessel's hull, allowing any ship that is coated in Seaglass Slime to intentionally alter its bouyancy. Though primative in principle, the invention of the Flood Ballast transformed navigation by allowing ships the ability to submerse themselves without harming the vessel. This allowed navigation to go from a dangerous curiousity to a practical means of transporting people and goods.

While Seaglass Slime creates the protective membrane that keeps seawater from crushing the vessle, it is incapable of making the vessel sink. In fact, a properly built wooden ship remains naturally bouyant. Flood ballasts replaces trapped air within seawater, increasing the ship's mass without changing its volume and granting it the ability to sink.

Design

Flood Ballasts are large, reinforced chambers built between the keel and the cargo deck. Their placement is always low within the vessel to help lower the ship's center, improving stability both on the surface and underwater. Each ballast chamber is a series of working mechanisms.

Flood gates, built into the bottom of the ship, open and fill the space with water. At the same time, venting towers extending up through the ship, release trapped air at the same or faster rate. As the flood gates fill the cistern, sailors lock Isolation valves to prevent water from overflowing or causing the ship to become unbalanced or capsizing. When the ship has sunk and the membrane begins protecting the ship, the navigator utilizes the Trim Screw, a large bronze screw in the Ballast tanks that moves water from bow to stern. This allows the ship to pitch up or down, depending on needs.

When surfacing is needed, sailors reopen the Isolation Valves and begin to pump out the bilge. The release of water into the membrane causes the Seaglass Slime bubble to expand and create oxygen faster, pushing the ship up for resurfacing.

Normal ships may have only 2 to 3 Flood Ballast Cisterns, while larger warships could have as many as six to twelve, with whole crews trains on how to operate them. In cases where the hull fails or the membrane is breached, ships may perform an Emergency Blow. Utilizing high-pressure air tanks,

Utility

Flood ballasts transformed Seaglass-coated vessels from experimental diving bells into fully navigable submarines. By allowing a ship to control its buoyancy, they made prolonged underwater voyages practical and reliable.
Outside military applications, flood ballasts have revolutionized deep-sea salvage. Furthermore, Merchant captains use submerged routes to avoid storms, sea monsters, and pirate-infested waters, while scholars have gained unprecedented access to the ecosystems and civilizations of the ocean floor.
Modern underwater vessels are rarely built without flood ballasts. The technology has become as fundamental to submersible navigation as the rudder is to surface sailing.

Social Impact

"The Sail may have conquered the wind, but my ballast has conquered the deep! With this, nothing is impossible

— Mondar Cote, Hematian Engineer

The invention of the flood ballast is widely regarded as one of the defining technological achievements of the modern maritime age. Together with Seaglass Slime, it opened an entirely new frontier beneath the waves, reshaping commerce, warfare, exploration, and diplomacy.
Entire industries emerged around underwater navigation. ballast engineers, Seaglass harvesters, underwater cartographers, salvage companies, and deep-sea merchants became vital parts of imperial economies.
Furthermore, The technology also dramatically altered naval strategy. Fortified harbors that had stood impregnable for centuries suddenly faced the threat of attack from below. Coastal defenses evolved to include submerged barriers, underwater watch stations, and sea mines.
Beyond economics and warfare, flood ballasts changed humanity's perception of the sea itself. Once viewed primarily as an impassable barrier or a source of food, the ocean came to be understood as another realm to inhabit and explore. Previously unknown and unreachable civiliations opened their borders to new trade and ancient ruins long lost have been rediscovered. Though these discoveries have opened to new undersea imperialism, with one ancient cities and states becoming overpowered and taken by mighty empires.

Related Species

• Seaglass Slime

Flood Ballast systems are among one of the most expensive, and technically demanding, additions one can add to a vessel. While basic principles are understood throughout the maritime world, constructing the system requires specialized facilities and expert shipwrights to construct reliable, water tight systems and pumps. Furthermore, it also requires skilled alchemists who specialize in Seaglass Slime to ensure the coating is put on properly.
Most civilian ships which can submerse are large merchant ships or scientific expedition ships. Outside of these examples, most large scale navies utilize these submersible vessels for reconnaissance, blockade running, or surprise attacks against enemy ports. Another reason is to assist in the raising of islands from within the Bottomless Ocean, as these islands can be added to continents or archipelagos to extend population growth. Furthermore, these submersible ships are used to fight rival nations of merfolk or fishpeople which exist under the sea.
Pirates and Pirate Lords also utilize them for similar reasons, but to attack imperial powers or sabotage imperial trade to gain an upper hand.