Kitty,
As far as we know Delf didn't write this line. The nearest thing to it he wrote is in his 6th verse where he puts,
'.....................the midnight hour was passed,
Their little craft was battling there with the fiery blast.'

Which we presume inspired the line in the later chorus. There is no mention of 'long' or 'longed'. If the Filey men had learnt it orally as seems to be the case they could easily have misheard it. On the only surviving recording the word is 'long...' but the ending is difficult to say for certain. If we take the spirit of what Delf actually wrote 'long did' seems to be the nearest.