The HMS Posideon, which is really called the Sea Trident, is a Stormchaser Sloop under the command of Captain Tyler Wellington.
While sailing aboard the HMS Nobel (Noble Titan), Wellington noticed its leaks and chipped wood. Although the Nobel was a new ship, it was nearly destroyed in the Invasion of Ireland. He ordered a new ship to be constructed for him to go along with his promotion of Captain in the Navy.
The Sea Trident is an upgraded ship, capable of taking down entire Spanish Treasure Fleets. It is the newest ship in the British Navy.