Glossary - Part O

•   Occulter: A mechanical apparatus powered by a falling weight, spring tension, the heat from the lamp acting on a fan assembly, or an electric motor, used to momentarily obscure a constantly burning lamp to give the light an occulting character.

•   Occulting: A light that appears at regular intervals briefly interrupted by periods of darkness, which are shorter than the period of light.

•   Off Shore Tower: Monitored light stations built on exposed marine sites to replace lightships. Sometimes called Rock Lighthouses.

•   Off Station: A floating aid to navigation not on its assigned position.

•   Optic: A navigation light lens or reflector apparatus.

•   Order: A measurement of the size of a Fresnel lens, with 1st order being the most powerful (and largest) and 7th order being the least powerful (and smallest): 7th, 6th & 5th order: small harbor and inland lights.

•   Ornamental Lighthouse: A decorative structure suggestive of a Lighthouse but holds no historic value.

•   Outer (or front) Range Light: The light in a pair of range lights that is situated in front of the other as viewed from the water.