Seriously ... Herakles was the son of the king of the Immortals ... why in the world would he take a raft to Erytheia?
Herakles was a fighter and a lover ... he was NOT a Boy Scout trying to get his raft builder merit badge ... but even if he had talked some Boy Scouts into building a stupid raft for him, Herakles would not have used it to sail to Erytheia ... and really ... how was he supposed to get the cattle back to Greece? On a raft?
Seriously ... get serious.