Hi Rachel, missed you posts for some reason, now your links are kaput.
Re the Dredger location; don't know if this link will work but the dredger wreck is marked.
http://www.visitmyharbour.com/harbou...our-chart-2012
zoom in and find the north pier and follow a line straight out to sea to the "1/8 wk" -(wk = wreck) it is about 275 metres from the end of the pier, and about the same distance north from the pole on the pan rock ends you mention (pole is now keeled over and gone)