Scrap the chords above! The tune is really more like this and, trust me, it's really stabilized now (copy and paste into WORD/TIMES/12 to line up chords):

Dm-------------------------------Gm------------Dm-----------C-----Dm
We were schooner-rigged and rakish, with a long and lis-some hull,
---------------------------------------------Am-------------------Dm
And we flew the pretty colours of the cross-bones and the skull;
---------------------------------------------Am------------Dm
We'd a big black Jolly Roger flapping grimly at the fore,
-------------------------------Gm----------------Dm----------C-Dm
And we sailed the Spanish Wa-a-ters in the happy days of yore.

Sounds something like "The Range of the Buffalo" which is not too surprising.

Cheerily,
Charley Noble