▁pier ▁constructed , ▁and ▁sl u ice ▁gates ▁that ▁tra pped ▁the ▁se aw ater ▁at ▁each ▁high ▁t ide . ▁At ▁low ▁t ide ▁the ▁gates ▁were ▁opened , ▁fl ushing ▁the ▁sand ▁out ▁of ▁the ▁har bour . ▁Hence for th ▁the ▁village ▁became ▁known ▁as ▁Se aton ▁S lu ice . ▁ ▁The ▁har bour ▁remained ▁like ▁this ▁until ▁the ▁ 1 7 6 0 s , ▁when ▁Sir ▁John ▁Hus sey ▁Del aval ▁had ▁a ▁new ▁entrance ▁made ▁for ▁the ▁har bour ▁by ▁bl ast ing ▁a ▁channel ▁through ▁solid ▁rock , ▁providing ▁what ▁was ▁known ▁as ▁' The ▁C ut ', ▁ 5 4   ft ▁deep , ▁ 3 0   ft ▁wide ▁and ▁ 9 0 0   ft ▁long . ▁The ▁new ▁channel ▁was ▁opened ▁in ▁ 1 7 6 3 ▁and , ▁as ▁a ▁result , ▁the ▁land ▁between ▁the ▁old ▁har bour ▁entrance ▁and ▁the ▁new ▁channel ▁became ▁an ▁island , ▁known ▁as ▁' R ock y ▁Island '. ▁The ▁new ▁channel ▁could ▁be ▁se aled ▁off ▁at ▁both ▁ends ▁to ▁allow ▁loading ▁to ▁continue ▁no ▁matter ▁what ▁the ▁state ▁of ▁the ▁t ide . ▁On ▁the ▁other ▁side ▁of ▁the ▁old ▁channel , ▁opposite ▁Rock y ▁Island , ▁was ▁a ▁ball ast ▁hill ▁known ▁as ▁Sand y ▁Island , ▁built ▁up ▁from ▁the ▁ball ast ▁of ▁ships ▁entering ▁the ▁har bour . ▁The ▁ball ast ▁hill ▁and ▁The ▁C ut ▁can ▁still ▁be ▁seen . ▁ ▁The ▁new ▁entrance ▁proved ▁to ▁be