The boaters -- two Americans, one Canadian and six from Hondurans -- left Roatan Saturday for what should have been a two-hour trip to Utila, ABC News reported.
Rear Adm. Jake Korn, commander of the Seventh Coast Guard District, said had the boaters had a registered emergency position indicating radio beacon on board, they would have been found more easily.
"EPIRBs help us respond quickly to the exact position of mariners in distress," he said in a Coast Guard release.
Rescue crews searched an area more than 4,502 square miles before finding the boaters Wednesday, the release said.
It was unclear what kind of supplies the boaters had on board and what their condition was, ABC News said.
"They will now be evaluated medically, and there's no information on where they'll be headed," U.S. Coast Guard spokesman Lt. Cmdr. Gabe Somma said.