Ah, I can see the logic, although using that...one andalite year would then be, at most, barely more than five years earth time...in which case Ossanlin would actually be five and Efaen would be five or six...idk. :p
And yeah, he's young, but I realized my estimation was off by a few years. When I was fourteen-fifteen, he would've been nineteen or so...which would actually put him at about thirty now that I think about it. Using the logic from above then he'd just barely be six...
He graduated quite early from the academy (around age 16-17 equivalent). I'd have to go into his back-story to look for sure, but I believe he spent a grand total of a month, maybe two, as an aristh. Then he was promoted to Warrior for a short time before being appointed TO of his Dome Ship the Galaxy Tree. After serving as TO for several (human equivalent) months, there was an unexpected battle in a backwoods system while the Tree was on patrol. The Tree stumbled across a small squad of Yeerk ships. The First Officer was an accomplished fighter pilot so he went out with the stunt craft to fight. His ship was destroyed after he ended several Bug Fighters. When the Tree started sustaining direct fire from a Blade Ship, explosions rocked through the ship. One particularly powerful explosion threw the Captain across the bridge where he suffered a fatal head-injury. As TO, Ossanlin was forced to take command and barely destroyed the Blade Ship with a little cleverness and a lot of luck. Turned out that the First Officer had been slated to take over command of the new Mark III Dome Ship Tyrennian and Ossanlin was going to be offered the First Officer position to replace him on the Tree. The Tree was so badly damaged that it had to be scuttled and scrapped for parts so there wouldn't be any more officer positions on that ship obviously. Since both the Captain and the First Officer that had been slated to be promoted had been killed in the line of duty, the solution that the Electorate came up with was to promote Ossanlin to the position of Captain aboard the new Dome Ship at the ripe old age of about 19 (human equivalent).