Possible Clues:

• Stern guard for Captain Dorling
• Turn fat and feeble in the stern on board
• The opposite of being fat and also delicate makes it hard to go overboard
• Well-padded backing applied to weak barrier aboard ship
• Welsh river bird seen round the stern
• The barrier on board is stern but weak at last
• Backward, overweight and weak on board
• Captain Dorling identifies corncrake on Welsh river
• Come at the end with a couple of females entering bar on deck
• Barrier around ship's stern