Hi Robertnaish,
To legally teach you need several pieces of paper:-
1. You need to have some form of recognised accreditation (In Oz, thats IKO, but could be BKSA)
2. You need to have insurance to the tune of between $10M-$20M (Depending upon council, the amount varies but minimum is $10M and again depending upon council, you need to have an approved insurance company not an offshore insurer). IKO Insurers were not recognised by JCC so I had to get an Australian underwriter.
3. You then need the councils approval and permits to operate a business in a public Place. Called a TIPP (Trading In Public Places) License. If you operate your business on Public or council lands, you need it! (Fines are Like $5000 first offense). All those PT's you speak of should have legitimate permits from council. I'd say if one does, they all will.
4. You also require permits from the relevant waterway authority (In WA it is D.E.C. or Dept. Environ. and Conserv.), in NSW it would be Waterways. This may or may not be necessary, need to check with your relevent authority.
If you have an accident teaching and don't have relevent permits, you are deemed to be operating/trading in contravention to the law which null and voids your insurance. So realistically, if you teach illegally, you may as well save money on insurance coz it wont help you anyway.

INsurance costs anywhere between $3000 and $5000 p.a. and that is soley Third Party. Other insurances are also sensible and are cost Plus.
Disclaimer: I am not advocating teaching without permits or insurance. Do it properly or don't do it at all.
This is why there aren't too many legal schools Australia wide. I believe of the 8 or 9 schools in Perth area, only 5 are legal to my knowledge. Up to you to guess which are which. [}:)]
Cheers,
DM