The centroid of ABC is G. Find BG.
BG = 3*sqrt(7).
Draw median \(BM\).
The length of \(BM \) is \(4 \sqrt{13}\).
By the properties of centroids, \(GM: BG = 1:2\)
This means that \(BG\) is \(\color{brown}\boxed{8 \sqrt{13} \over 3}\)