The passage from Tantas is well marked and quite deep. Watch the southern side of the ramp as it was full of silt when we were there. couldnt launch a 4m tinny there.  

We only tried fishing there once but didnt have any luck though a mate went and got a wahoo and coronation trout. Further south, we bottom bounced squid in 15-20m and did quite well on bottom species. 

 We were also going to the gulf for a fish....any pointers on how far out or were to go ...never been there...got a 5.5m cuddy aluminium 140 ltr fuel....

 Not a lot outside pelagic in the gulf, can always try the shoals (on map) but they are pretty heavily fished due to being easiest area to find.

Better off sticking to the west side at that time of year. It's a decent treck back to town and the gulf from Osprey and typically SE winds blowing in the gulf that time of year so wont be very nice. 

From Tantabiddi, troll the back of the reef in 20-22m and chance of mackies. I usually head out the main channel and then head down to south passage before I start trolling. 

Inside the reef, I just anchor up wind of any bombies and drift extra lightly weighted baits back on to them. Will pick up spangoes and the yellow tail emperor are usually a pest. 

Otherwise.... Walk up to the point between Osprey and Sandy Bay and same as above.... Drift lightly weighted baits along or over the reef for the exact same and save the fuel money!

Double up

 Good advice so far and lines up with my experience. Don't be afraid to troll a bit shallower as we've got plenty of mackies around 17m too. Osprey Bay is a beautiful spot and Sandy Bay great to swim and snorkel. It will be where we camp the next time we go.

Seemed to me the coronation trout seem to favour around 15m along the reef front, so a zigzag troll in the 15-20m zone could yield anything, but especially mackies, or it you use a 10m depth deep diver some trout can add to the bag. Otherwise have found a drift in 25-30m with floaters or live bait half way down the water column can get the macks. If the wind has some west in it and you do go over onto the Gulf side, don't forget you can also get squid along the reef edge south of Bundegi ramp.

 Just another question regarding  travelling inside the reef ...can you travel from Tandabiddi ramp down to Osprey and moor there..if so is there safe passage through the reef to outside?

Haven't been to Osprey enough to notice if boats ever moor up in there.... I suspect that is probably because most people staying there are towing caravans and you can launch tinnies at Osprey. 

Osprey is approx 50km south of Tantabiddi so would be a much easier trip outside the reef than having to keep an eye out for coral bombies the whole trip inside. There is a passage as Osprey..... I've never been through it but to know what it is like if the swell is up.