Well its been a while since I played WC3, but as I remember it, I hated this matchup because the Tbolt couldn't outmaneuver or outrun a Vaktoth so if he had his back to you, you just kept getting a face-full of turret fire. AND you couldn't trade blows with him face to face either, because he was just as well armed/armored as you and you had to face probably 3-4 of them total. Honestly if you thought it was easy I don't think we were playing at the same difficulty level. I've played a lot of games and this is one of those things I just remember as being a major source of frustration.
If you were in a quicker ship, like an Arrow, Excalibur or (hypothetically) a Sabre, Vaktoths were no deal because you could just pound them from 4 or 8 o'clock where the turret couldn't hit you. In a Tbolt it's harder to do that.