You can only yell so loud and its tough to hear you over the roar of the river. So better play it safe and get a whistle! At least you can use it to tease your neighbors dog. Truth be told every paddler out there should have one of these. Most states its a requirement. The Fox 40 whistle will last forever and it doesn’t corrode like a steel one would. Bottom line be safe get a whistle. Make sure you are heard! The Fox 40 whistle is LOUD! These whistles are invaluable for signaling rescuers. Boat safely and carry the necessary equipment. It may save your life.