Ijmuiden locks

We had to pass through the locks to enter the North Sea Canal which will take us the 24km up to Amsterdam. We passed through the smallest lock which is used by recreational craft and always takes a little while. It works 24 hours a day and is completely free of charge. Red lights turn to green after the road bridge and lock gates swing open . A scramble to get tied on making sure that fenders are in place to preserve the shiny paintwork on the hull. Gates and bridge shut.Will we be going up or down ? Actually most of the Netherlands is below sea level so we dropped about a metre.
We first went through these locks in the early 1980's in our first little wooden boat. We had had a long sail up from southern Netherlands and arrived at midnight on a sunday. We were not sure where to go and were just trying to work out where the locks were when a harbour patrol boat offered to escort us to the right place.There are four locks here ranging in size from the yacht lock to one big enough for cruise liners .For some reason we were popped into the huge lock which was so large we just motored round and round. We had to laugh when they call out to us to find out what our gross tonnage was ...... 4 tonnes ! Again this was all free of charge.