Incandescent bulb vs LED bulb

Incandescent bulb vs LED bulb

We often get questions about the use of LED bulbs in our conventional navigation lights. An honest question, since the approved incandescent bulbs don’t come cheap and consume more power. However, concerning  the alternative LED bulbs there is a “but”, a very big “but”: they are simply not approved according the international maritime regulations (Marine Equipment Directive). This LED-alternative causes that your navigation lights are not compliant and the corresponding certificate’s are no longer valid. Imagine what would happen in a case of collision and the use of inappropriate LED bulbs...

But why doesn’t DHR get an approval for LED bulbs? The answer is simple, it’s not possible to have replacement LED bulb that is suitable for navigational light purposes. The explanation is somewhat technical:

1. An approved incandescent bulb has a wide visible spectrum that can be detected by the human eye. LED bulbs, on the other hand, have more narrow spectrum.
The following diagram shows the difference:

So when a led bulb is used in combination with a coloured lens almost no visible light passes through the coloured lens, especially with red lenses. That’s the main reason why LED replacement bulbs are not approved.

2. Another reason is that the conventional navigation lights are designed and approved  to be used in combination with special incandescent bulbs. In case of a sector lantern, the light output won’t be cut-off at precisely the right angle if a LED bulb is used. This can cause a decrease in visibility and thus decrease in safety.

3. Conventional lanterns work with a Fresnel lens. The lamp is designed in such a way, that the filament of the incandescent bulb is exactly positioned in the centre. If you use a LED bulb, (which has several LEDs) the light isn’t distributed correctly by the lens creating an unwanted light output. This makes the navigation light not visible  in all desired vertical angles and therefore not safe.

This is why LED bulbs cannot be used in conventional lanterns.

DHR, we know why, we know how.