A truly huge number of nautical terms have entered normal parlance. Some are so deeply engrained that we don't even realize they were originally nautical metaphors. Examples:

* Taken aback

* Above board

* Adrift or at sea

* Afloat versus underwater

* Ahead

* All hands

* Anchored

* Awash

* Batten down the hatches

* Bitter end

* Boiler room

* Buoyed up

* By and large

I stopped after B. Also, "cut of your jib", of course.