They are many things that can tear a ship to pieces with one mighty blow, all the more reason to keep the gates up, so they never get into the harbor. - Sailor
Halting the BeastsOriginally the Sea Gates was used as a means of defense against the many sea monsters that resided in the oceans of the world from getting into a harbor. It would often go on a rampage and cause damage to the ships and harbors in the area. The first gates were created in the Eastern Lands due to their dependency on the ships they had for fishing and trading, and wood was considered rather expensive as their desert environment makes it only possible for a few trees to survive.
Towers: Two towers or fortifications must be built to connect the chains. They also must be across from one another often while the chain is across a body of water. Depending on the distance between them, the chain length will vary, and if necessary, more towers will be built to strengthen the chain's grip on the water. Tower strength will also vary to prevent it from being damaged if more force is applied to the chain. Along with defenses in case it is ever attacked to avoid its destruction, often being projectile weapons and fortified gates. Chains: The chains of a sea gate must be strong and can take the stress of an object pushing on it without breaking. This means they are just more extensive and stronger than most chains. It also must be controlled by an anchor system that wraps around the chain to raise and lower it. They are also meant to last a long time before needing to be prepared or replaced again. Nets: Depending on where a sea gate is, they may have netting deep underwater as a defense against more giant sea creatures from getting in. They will often be thick and large to ensure that nothing too large is strong enough to easily break through it. There may be metal spikes or other items attached to it to scare anything away.
Protected Waters: Since the creation of the sea gates, harbors have become much more protected than ever before as it has allowed waterways to be protected from both sea beasts and hostile ships such as Pirates from getting into harbors and wreaking havoc. As long as the gates are up, nothing can get into a harbor or waterway without permission. There are also places where tolls are needed to be paid to cross them. Water Blockades: These gates have also become a way for the militaries to block access ships from entering harbors and waterways during wars. Using them to deny the enemy access to entering waterways and trap them to capture and destroy ships. Making it essential to either capture or destroy a sea gate to allow access to waterways unopposed.
Access & Availability
Sea gates are standard across most parts of the world and are often used in most harbors and even rivers to settlements that use them as defenses and to block access through waterways.
The chains are attached to two towers or defense positions linked together in a series of metal chains meant to stop anything in the water from passing them and gaining access to the water past it. Depending on the depth of the water, the chains will go deep underwater to create a defensive wall of chains designed to keep anything too significant from getting through them. Often using netting to ensure that nothing gets through them in the deep waters.
Sea Gates did not become well known until the rising of the Paranth Sultanate and the desire to protect their trading ships from being destroyed by anything while docked.