I wouldn’t use the International Alpha flag. Most boaters don’t even know what the reg. red with white stripe flag means. More likely it’ll draw attention to boaters if your using a bouy/flag set up without a boat around. Thinking that its something floating around on the surface. Use the traditional red/white dive flag. An international ship will not deter from thier course even around a small boat. Your not going to be that far out into any shipping lanes from shore anyways. If your in US waters then use the North American dive flag version.