What sound signal should a powerboat give underway in fog?

A powerboat underway in fog should sound a prolonged blast on its horn at intervals of not more than two minutes. This signal alerts other vessels to its presence in low visibility conditions. Additionally, if the vessel is maneuvering or making way, it may also sound short blasts as required for specific maneuvers. Always be prepared to adjust your signals based on the surrounding conditions and the presence of other vessels.