What is the height of the masthead light of a power-driven vessel of 12 but less than 20 metres?

The height of the masthead light for a power-driven vessel that measures between 12 and 20 metres in length is specified to be not less than 2.5 metres above the gunwale. This requirement is outlined in the COLREGs to ensure that the visibility of the vessel's lights is adequate against background lights and structures, particularly in busy or congested waterways. A height of 2.5 metres strikes a balance between being high enough to be seen but also practical for vessels of this size.

In contrast, options that suggest heights of 1.5 metres, 3 metres, or 4.5 metres are not correct as they do not align with the COLREGs' standards established for vessels within this length range. A height of 1.5 metres might not provide sufficient visibility in certain conditions, while 3 metres and 4.5 metres exceed the requirements set forth for this size category. Therefore, the specification of 2.5 metres is the correct and pertinent guideline to follow for masthead light placement on vessels between 12 and 20 metres.