h90:
Bowmouth: of course thats possible, but in every sport illegal things may happen. with the same arguments you could block people from renting a car or motorbike (making car races, theach the friend, drive drunk).
It would mean to forbid every diving without a company.
As for Thailand there is no law which does not allow me to instruct my friend without beeing certified.
If someone is certified as OW, AOW or higher that should be enough to know what they are doing.
I've seen the effects of uncertified instructors on new divers or people diving without being taught and no supervision.
The new divers funnily enough ended up dead. Actually, it was not that funny at all. During a search conducted at the dive site, I did find the 'missing' diver. A lot of hurt was involved.
So, please, go ahead and kill some of your friends whilst you teach them, I wonder if you're still looking for tanks to rent after that, since as you stated , there's no law in Thailand that forbids this.:11: (Is that so, it wouldn't surprise me).
Think twice before you write stuff like that, there's a reason that there are training agencies out there.
It seems that some dive shops have their heads screwed on the right way and try to prevent stuff like this to happen.
In respect to the dive shop I work for now, we have rented tanks to individuals before, but aren't too over zealous to do so, you better have a very good reason and are willing to leave a deposit.