Just got back from a 8 day bareboat Charter with DYCs out of Grenada, In SVG used mooring balls in Clifton right off of happy island one night. The moorings are monitored by the Tobago Cays Marina park rangers and looked to be in good condition, 60EC for the night. If you go into Union, and you see a boat boy waving you off of the mooring balls infront of happy island, ignore him, He is just trying you to get to use his mooring ball and charge you 60 ECs for his mooring ball for a couple of hours

Used Mooring ball in Salt whistle bay (good condition - 60EC) - Boat boys were very helpful and appreciated the tip and the cold beer. Used a mooring ball in Tobago Cays (60EC) but this is the place you probably want to anchor unless you are in the channel between the two islands.

Also used a mooring ball off of Palm island - Free! but it was rollie.