The pleasure craft apparently had three adults and six children on board when power was lost. An anchor was lowered to keep the vessel away from the shore, and help was sought about 4.45pm.
Lox Kellas, of the coastguard, said conditions were calm, everyone aboard the craft was wearing a lifejacket, and the initial alert (apparently near Heyward Point) and the tow back to port went smoothly.
The Vivienne J was in the area and helped the coastguard to bring the craft to safety, he said.