The Aay'han was a DeepWater-class light freighter often used for joyriding. In 21 BBY, Kal Skirata purchased it second-hand from a Rodian in Calna Muun on Agamar for the price of 80,000 credits. He bought it because he wanted a craft with underwater capabilities to aid with his search for the Kaminoan scientist Ko Sai, as he believed that she was hiding on a water world.
Kal Skirata's adopted son, Ordo Skirata, suggested the name Aay'han for it, which was a word from Mando'a that translates roughly as a state of mind of a peaceful and perfect moment where you are surrounded by friends and family, but at the same time missing dead loved ones to the point of pain. Skirata used this name in honor of a clone who died during training, Dov, and Skirata's own adopted father Munin.
They soon got a chance to test it out, as just after they purchased it, they traveled to Mygeeto in it, to extract Walon Vau, who had fallen through Mygeeto's ice and got stuck in a crevice while trying to rob a bank.
After rescuing him, they flew the Aay'han to Bogg V in the Bogden system, to carry out modifications to it and fit it with military-grade sensors and weapons. They also rendezvoused there with Mereel and General Bardan Jusik, who informed Skirata that Ko Sai had been sighted on Vaynai and that Delta Squad had been sent after her.
Using Jusik's information, they tracked her to Dorumaa and Skirata, Vau, and Mereel flew there in the Aa'yhan. Under the alias that they were there on a fishing trip, they used it to search underwater near the Tropix Island Resort and discovered a potential location where Ko Sai could be. They returned to Tropix Island to plan their assault on it and while there, purchased a Wavechaser, which Skirata nicknamed Gi'ka, to use as a runabout that could operate from the Aay'han. Shortly after, Skirata and Mereel found and captured Ko Sai and brought her back to the Aay'han to transport her to Mandalore.
Prior to the activation of Order 66, the Aay'han was moored in the Galactic City in anticipation of planned "strategic disappearance" to Mandalore for all members of Clan Skirata. The Aay'han was moored down there; courtesy of people who owed Jaller Obrim favors, to keep it out of sight.
After the death of Etain Tur-Mukan, the Aay'han was taken to Kyrimorut and was stored in a hangar concealed north of the house.
- The Complete Star Wars Encyclopedia