SL-300-2D5 Series
13-19NM Marine Lanterns
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Case 2:
SL-300-2D5-1-W, White, 17NM, Flash Character = Occ(3) 16s [2s on, 2s off,2s on,2s off,6s on,2s off]
1. Calculate the Flash Character Duty cycle (%)
= (2+2+6)/(2+2+2+2+6+2)*100 = 62.5%
2. With a range of 17NM, use IALA E-200-2 and determine the Effective Intensity (cd)
= 32,308cd
3. Using the Method of Modified Allard, determine the Peak Intensity (cd)
= 35,539cd
4. Calculate the desired Intensity step setting (0 to 32=100%) based upon the SL-300-2D5-1-W
Maximum Peak Intensity (cd)
= 35539(cd) / 46700(cd) * 32(steps) = 25 (rounded up)
5. Calculate the MULTIPLER (%)
= 62.5% * (25/32*100%) = 48.83%
6. Compare this to the Max Power Thermal Limit for a SL-300-2D5-1-W
= 34.375%
The MULTIPLER > 34.375% and exceeds the Thermal Limit.
As such, go back to Step 5 and reduce the Intensity Step from 25 until the MULTIPLIER is less
than Max Power Thermal Limit.
7. In this example, an Intensity Step of 17, results in a MULTIPLIER of
= 62.5% * (17/32*100%) = 33.20%
Which is less than the Max Power Thermal Limit of 34.375%
8. With this reduced intensity step, recalculate the reduced range.
Peak Intensity = 33.2% * 46,700cd
= 24,809cd
9. Using the Modified Allard method in reverse, the new Effective Intensity is
= 22,554cd
10. Using IALA E-200-4, the new range is reduced to 15.3NM. (1.7NM less than desired range of
17MN)
