It's in Ab major - no wonder it sounds strange with your chords, unless you use a capo at pos. 1. With this, the chords are

 
While 

G  
cruising round Yarmouth one 

Em  
day for a spree

 
I 

G  
met a fair damsel the wind blowin 

D  
free

 
I'm a 

G  
fast going clipper my 

Em  
kind sir said she 

 
I'm 

G  
ready for cargo my hold is quite free

 
Singin 

G  
Falderal laddie I'd 

Em  
falderal day

G  
Falderal laddie I'd 

D  
Falderal 

G  
day

Still waiting for an expert to point us to a better tune for the DT, or a discussion of the various versions.