Blue Block says they set up camp on public footpath near warehouse, massed with hidden treasure and followed a pirate map which included a (small) bottle of rum. They woke up this morning with 4 other crews and a raft crew all in same location. Coordinated launch happened at 08:20 - police cars were nearby and a helicopter was overhead but they were supposed to launch at 08:30 - but launched early. Police came running down just as they were launching. The rafts floated away in the nick of time with hoisted sails. Police have been watching from the south bank since then. Reports that 5 boats got to jetty, floating there, apparently too shallow for the police to get there! One boat approached by police, told to get back to shore. Paddled around a bit, harbour master chased but they escaped to an island and got away from them! 30-40 forecast reporter saw 15 people launch with 7 boats: a catameran, a raft, lots of boats on the river. Locals were well up for it - the marina were well impressed with safety precautions taken. Many more peopl on the river than normal. Including local boats watching it. Harbour master reported to towing one of the boats - but it managed to escape.