Abstract: A signaling device for a water-skiing tow boat that displays a warning flag in the event of a fallen skier. The device can be attached to a boat hull or other structure and includes an electro-mechanical actuator operated by a local or remotely controlled switch or sensor to retract or extend the warning flag in or out of a weatherproof housing. To further enhance skier safety, an indicator light is used to attract attention in bright daylight as well as under low light conditions. The device can be operated by a radio-frequency link to remotely control the flag from any location around the tow boat and can be powered by the electrical system of the towing boat or by a rechargeable battery pack.