but they also said specifically DO NOT turn left too soon  when heading out -  stay on that N/NE line for several hundred metres past the opening cos the swells roll through past the opening on your left as your leaving and then of course approach on the same angle when coming back to enter the mouth

 Good to see the updated chanel markers and cardinal buoy; appreciate the post 

 Shallow water extends to the north of the black rock for a bit. But no need to leave it til the outer cardinal marker if there is no swell. It denotes "clear ground to the north" very conservatively laid. If it is breaking out to that mark, you have absolutely no right to be out there in a trailer boat. The biggest risk in that channel, IMO, is the bit I have marked in red squares against Oyster Reef. It comes up very quickly there, from about 5 fathoms to nothing, and it just breaks very suddenly, particularly bad on a run-out tide. Easiest to fuck up coming in, if someone else is coming out and you look like passing at that point. Get a bit far east to "give them some room" and next moment you will be picked up from behind and broach--and if you broach left, you'll likely end up on Oyster Reef.

 Did the run out a few times on my Hobie a month or so ago , good fun with small outriggers helping ! 

 You weren't one of the hobies getting dragged all over the ocean by big mackerel a while back?

 Na mate , wasn't that lucky , didn't stray to far , it's a bit lonely out there by yourself !