Nautical Equipment · Navigation Lights
MASTHEAD LIGHT CLEAR A-2, DOUBLE POLYCARBONATE LENS 370421
Double masthead light with polycarbonate lens: COLREG 225° arc, 6 nm range for ships of 50 m+, bulbs, and what to check before ordering.
What it is
IMPA 370421 is a clear (white) A-2 masthead light, double, with a polycarbonate lens.
A double lantern has two lights in one fitting. Glamox, for example, sells its 70M double-lens masthead light (225°) without a bulb and says the bulb has to be ordered separately.[2]
How to specify and order it
Order by the number of masthead positions. A power-driven vessel of 50 m or more under way shows a forward masthead light and a second one abaft and higher. A vessel under 50 m may carry only one. Each position needs a lantern.[1]
The code name does not define "A-2", so ask the supplier to state the rated range in nautical miles and the approval held. Under Rule 22 a masthead light must be visible at 6 miles on a vessel of 50 m or more. It needs 5 miles on a vessel of 20 m to under 50 m, and 3 miles from 12 m to under 20 m. Annex I gives 94 cd as the minimum intensity for 6 miles.[1]
Give the supply voltage and order the bulbs in the same requisition, with spares for both lights. Give the mounting as well, and match it to the existing seat or ask for an adapter.
Rules and approvals
Under Rule 21(a), a masthead light is a white light on the fore-and-aft centreline. It shows an unbroken light over 225°, from right ahead to 22.5° abaft the beam on each side. Under Annex I section 9, the minimum intensity must hold to within 5° of the sector limits. It must then fall to practical cut-off no more than 5° outside them.[1]
On a power-driven vessel of 20 m or more, Annex I section 2 puts the forward masthead light at least 6 m above the hull. If the breadth is more than 6 m, it goes at least the breadth above the hull, but need not be higher than 12 m. A second masthead light goes at least 4.5 m higher than the forward one. Section 14 leaves the construction and installation of lights to the flag State.[1]
Questions buyers ask
- What range does a masthead light need?
- Under COLREG Rule 22: 6 miles on vessels of 50 m or more, 5 miles from 20 m to under 50 m, and 3 miles from 12 m to under 20 m.
- Does a double masthead light come with bulbs?
- Not always. A double lantern holds two bulbs, and Glamox, for one, sells its 70M double-lens lights without them. Ask, and order the bulbs with the fitting.
Sources
- UK MSN 1781 (M+F): Distress Signals and Prevention of Collisions Regulations 1996 (COLREG text, incl. Annex I)
- Glamox: 70M MASTHEAD WHITE 225 W/O BULB, item 3581000000 (Series 70M double-lens navigation lights)
No prices: offers come from suppliers at the port.
Published by Sherif Awad, founder of GeoMarineHub — in ship supply since 1990, a family business since 1981 (45 years). Last checked .
Specification · IMPA 370421
Read off the catalogue name · priced per piece
- IMPA code
- 370421
- Unit
- PCS
- Colour
- clear
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