How to stop the illegal boat "refugees" for little cost

The problem of the illegal boat "refugees" can easily be solved at a fraction of the present cost by issuing appropriate orders to the Australian Navy.

The people smugglers need to be officially told by memo etc that henceforth our Navy will patrol the Indian Ocean solely by submarine and there will be NO surface vessels available for taxis service. At last we have found a use for our operational Collins Class submarine (sorry smugglers, it can't carry passengers). All surface vessels will until further notice be confined to the Pacific and Southern Oceans (they can check out the whales and report any poachers).

Also a warning should be attached to the smuggler memo about the deadly hazards of trying to land on mainland Australia, mention being given of the Great White Pointer shark, deadly sting rays and blue-bottle jelly fish, huge crocodiles, poisoness snakes, scorpions and lack of water along the largely uninhabited coastline. They land at their peril and may encounter stroppy kangaroos. I suggest that genuine refugees come via our front door with our approval, and do not try and sneak in via the back door.