This phrase actually came from a phrase from the 19th century. "More days, more dollars." I've found the quote in several books and magazines in the 19th century. The oldest I've come across is 1853 Adventures in Australia pg. 38 and in 1857 in Nine Years a Sailor, pg. 273
The phrase refers to how the sailors were paid and the monotony of their days at sea.
Here's the quote from Adventures in Australia
A Calm at sea is, when it continues for several days, a most wearisome and monotonous occurrence. Every sail flapping lazily against the mast, the rigging creaking and straining with the heavy roll of the ship, and to no purpose, as far as regards the attainment of our object, the completion of the voyage. It is what is called by Jack himself, a sailor's wind, because their axiom is " more days, more dollars," especially at the high rate of wages they are now receiving on board of the ship in which this is penned. But even he gets tired of it, the pulling and hauling of the ropes for every shift of light airs, is what he calls " humbugging;" and it does not generally improve the temper of the " skipper," i. e., commander; his perceptions are doubled, and he sees faults where, under a fine stiff slashing gale, he would have seen none. All seem alive and exhilarated, when going along under a ten-knot breeze ; even the mates throw the reel over the side of the vessel with a swing of satisfaction and excitement.