The only time I would recommend people doing the Yongala trip from Townsville is if they've got time up their sleeves. As in, they're in Townsville for 2-3 weeks at a minimum, so if it gets cancelled on their original date, they've still got alternative dates to do it. The trip only runs twice weekly, and it's not always a pleasant journey out regardless of the weather - it's a shade over 3 hours each way. I've seen it get cancelled 6 weeks in a row (earlier this year). It's not a bad way to do it, the boat from Townsville is nice, and fairly large - whereas Yongala Dive has smaller boats that bounce around a lot.
There's nothing wrong with Adrenalin Dive who run the Yongala trip from Townsville, it's just that it's unreliable due to the weather around these parts. If you've only got a day or two, you're best off going to Alva Beach and diving the Yongala from there. It's at much less risk of being cancelled, a far shorter 40 minute boat trip out, and the conditions are generally calmer on the way.
There's nothing wrong with Adrenalin Dive who run the Yongala trip from Townsville, it's just that it's unreliable due to the weather around these parts. If you've only got a day or two, you're best off going to Alva Beach and diving the Yongala from there. It's at much less risk of being cancelled, a far shorter 40 minute boat trip out, and the conditions are generally calmer on the way.