Discovery - Swing Tree chords

I'm really into this band, Wes and Rostam work wonders together.
This is "Swing Tree", which is extremely simple
[ Tab from: http://www.guitaretab.com/d/discovery/206611.html ]
Bb
If I was a boy at sea I would be
Gm
Swinging from a broken tree I would be
Bb
Down on my back looking 
Gm
Up at stars at night


Repeat the Bb- Gm progression over and over throughout the song, it doesn't change. 

Nifty right?
Remember, you can stream the whole album at dscvry.net.

-shiek