The leak was still not found. We knew the water entered the interior of the boat through a stringer under the cockpit, but we din't know where it came through the laminate of the hull. So we removed the rudder and... YES: on both sides of the skeg a crack between the laminate of the hull and the on the inside laminated cavity in which top of the rudder is mounted.

Dolf's clever trick with the bicycle pump proved that this was the leak we were looking for. We concluded that this leak was a result from a heavy crash from the ruddder against the hull: the stopper on the quadrant was broken!

So we did some grinding, repaired the laminate with glassfiber and epoxy, some grinding again and four layers of coating... put the rudder back in it's place and the job was finished! We re-shaped the rudder into a smaller but more effective device, to reduce the pressure while retaining good steering characteristics. More about the boat: construction rudder keel