The options are:
1) get one of those GPS and also get one of those GPS coordinates data of coral formations and shipwrecks for the UAE. I recall seeing one being sold in one of the tackle shops....can't remember which one though!
2) make friendships with those local fishermans who are well versed in the fishing spots within the UAE.
3) go on one of the well known fishing charters.....armed with a GPS device (actual GPS reciever....or a fone with build in GPS receiver.....e.g Samsung, Nokia, HTC etc....if you need to be a bit more discreet).
4) A fishfinder sonar can be useful PROVIDED you know where to go to....otherwise U will just be wasting your time trying to locate the spot....without any particular coordinates.
5) The best way of knowing the productiveness of any areas without the use of a fishfinder and/or gps ...is to look out for fishtrap pods which had been laid by the local fishermen BUT....... need to be extra careful when fishing near these pods to avoid your lines/hooks/sinkers from being entangled with them. As they have baits in them....they attract fish.

These pods are usually marked by floats.
Cheers!