Perko, Masthead, All Around Light, Combination, 12v Volts

In accordance with the ‘72 COLREGS, navigation rules state that the center of the bulb filament of white lights must be mounted at least 1 meter (approx 40”) above center of the filament of the red/green lights. The "vertical height" (H) of a light is measured from the deck of the boat to the center of the light filament. Most pole lights (all of Perko’s) are sold by their "nominal (or approximate) overall length".

Three factors affect the difference between overall length and vertical height. 1) The depth the pole goes into the base is typically less than two inches. 2) The distance from the filament to the top of the light is typically less than an inch. 3) Rake angle can shorten the vertical height by as much as an inch (for bends under 16 degrees).

So, as a general rule, the installed "vertical height" will be between 2 and 4 inches less than the nominal length of the pole. Select the shortest light that will insure that the requirements are met after taking this difference into account. Be sure the light is long enough to be seen over any obstructions. If this light is too long to store easily, consider a old-in-half light for easier storage.