Try,
above board,all at sea,any port in a storm,batten down the hatches,betwixt wind and water,brought up short,chewing the fat,cut and run,deep six,between the devil and the deep blue sea,fish or cut bait,flogging a dead horse,fly by night,grease the skids,gunboat diplomacy,hell's bells,weather eye,true blue,taken down a peg or two,(our favorite) splice the main brace,slush fund,shove off,ships that pass in the night,rub salt in the wound,scraping the bottom of the barrel,pipe down,shake a leg,over a barrel,letting the cat out of the bag,