Jawin' tackle

This means he will stop talking. {As expounded upon in our chapter for H.M.S. Pinafore, a sailor would probably pronounce the second word as TAY-kill; but there is less reason for it in this context, and the meaning might be more obvious if it were spoken in the usual lubberly way: TACK-ill.}

Context: 
I'll just stow my jawin' tackle and belay
Opera: 
Act: 
Act I