What is a major disadvantage of dead reckoning as a navigation method?

Dead reckoning is a navigation method that relies on calculations of distance and direction traveled from a known point, rather than external visual references or GPS data. A significant disadvantage of this method is that it can lead to substantial navigational errors. This occurs because dead reckoning does not take into account variables such as wind drift, ocean currents, or other environmental factors that can affect the actual path taken. As a result, if the initial course or speed is miscalculated or if unforeseen circumstances arise, the navigator can easily find themselves far from their intended position, thus compounding errors over time.

In contrast, the other options highlight different aspects of navigation that do not directly address the intrinsic limitations of dead reckoning in terms of accuracy and reliability. The requirement for visual references is more relevant to visual navigation methods, while time consumption and accuracy issues can vary depending on numerous factors not specific to dead reckoning alone. The core issue with dead reckoning is its susceptibility to errors that can accumulate without correction, making its navigational reliability a critical concern.