back and fill

Verb

back and fill (third-person singular simple present backs and fills, present participle backing and filling, simple past and past participle backed and filled)

1. To manage a sailing ship so that the wind strikes them alternately in front and behind, in order to keep the ship in the middle of a river or channel while the current or tide carries the vessel against the wind.
   • We brought the other end to the capstan, and hove in upon it until we came to the slip-rope, which we took to the windlass, and walked her up to her chain, the captain helping her by backing and filling the sails.1840, R[ichard] H[enry] D[ana], Jr., Two Years before the Mast. […] (Harper’s Family Library; no. CVI), New York, N.Y.: Harper & Brothers […], →OCLC
2. To zigzag, or make a pivot turn by alternately putting the engine in reverse and forward, while turning the wheel or tiller.
   • There were no bells in the engine hold and the signals were passed by word of mouth from the man at the wheel. Backing and filling by turns the desired position was finally secured and I heard the rasping roar of the chain cable as the descending anchor ran it out through the hawse hole.1923, F. Hopkinson Smith, The Arm-chair at the Inn, Chapter 10
   • These people brought up their lantern, then, of course; and as we backed and filled to get away, the precious family stood in the light of it--both sexes and various ages--and cursed us till everything turned blue1883, Mark Twain [pseudonym; Samuel Langhorne Clemens], Life on the Mississippi, Boston, Mass.: James R[ipley] Osgood and Company, →OCLC
3. (figuratively) To take opposite positions alternately; to flip-flop
   • Joe found McDowell a vast improvement upon Hagel. Where the latter had backed and filled and referred to his directors, McDowell, to whom responsibility was as the breath of life, decided instantly.1911, A. M. Chisholm, The Boss of Wind River