Doubled.2C paired or twinned locks Lock (water navigation)

doubled locks. left lock has boat in it, right lock (center of drawing) empty. on erie canal @ lockport

locks can built side side on same waterway. variously called doubling, pairing, or twinning. panama canal has 3 sets of double locks. doubling gives advantages in speed, avoiding hold-ups @ busy times , increasing chance of boat finding lock set in favour. there can water savings: locks may of different sizes, small boat not need empty large lock; or each lock may able act side pond (water-saving basin) other. in latter case, word used twinned : here indicating possibility of saving water synchronising operation of chambers water emptying chamber helps fill other. facility has long been withdrawn on english canals, although disused paddle gear can seen, @ hillmorton on oxford canal. elsewhere still in use; pair of twinned locks has been opened in 2014 on dortmund-ems canal near münster, germany.

the once-famous staircase @ lockport, new york doubled set of locks. 5 twinned locks allowed east- , west-bound boats climb or descend 60 feet (18 m) niagara escarpment, considerable engineering feat in nineteenth century. while lockport today has 2 large steel locks, half of old twin stair acts spillway , can still seen (without lock gates).

these terms can (in different places or different people) mean either two-chamber staircase (e.g. turner wood double locks on chesterfield canal: same canal has three-rise staircase called thorpe low treble locks), or flight of 2 locks (as @ thornhill double locks on calder , hebble navigation). also, double lock (less often, twin lock ) used novices on english canals mean wide (14 ft) lock, presumably because double width of narrow lock, , allows 2 narrow boats going in same direction double . these known broad locks.