The Coastie-candela confusion

(Every Monday, Wednesday, Friday -- a new Mainly about Boats column.)


IN THE CONTINUING SAGA of brass oil lamps for anchor lights, Nikolay R. reports thus:

After some searching, I have successfully located a local store that carries both the DHR and Weems & Plath brass oil lamp for a slightly more reasonable price than procuring it through a West Marine retailer.

I wonder, would the 10-inch anchor lamp be sufficient to meet the intent of international Col-Regs?
Cheers,
Nikolay R.

The short answer, Nikolay, is yes. The COLREGS say that if your boat is less than 164 feet long, you need to exhibit when at anchor at all-round white light “where it can best be seen.” It must be visible for two miles. (If your boat is less than 23 feet long, you don’t need an anchor light at all, provided you don’t anchor in or near a narrow channel, fairway, or anchorage, or where other vessels normally navigate.)

This light doesn’t have to be electric. The COLREGS say so. A flame from a kerosene lantern with a wick a half-inch wide and a half-inch high will do the trick. The regulations say a light needs a brightness of 4.3 candelas to be seen two miles away.

And just what is a candela, you ask? Why, heavens, it’s a unit of luminous intensity of course. You can think of it as roughly one candle-power, so your oil lamp needs to be the equivalent of 4.3 candles.

You sometimes see an advertisement for an oil lamp that states “Not Coast-Guard approved.” So who needs Coast Guard approval? The Coasties didn’t make the laws. They merely enforce them. If your all-round white anchor light can be seen for two miles it doesn’t matter if you’re burning grandma's drawers in a galvanized bucket. As long as they produce 4.3 candelas (as I’m sure your grandmother’s would) they’re legal.

And if the Coasties give you a hard time because you have a non-approved anchor light, slay them with this official definition of a candela:

“The candela is the luminous intensity, in the perpendicular direction, of a surface of 1/600,000 of a square meter of a black body at the temperature of freezing platinum under a pressure of 101,325 pascals.”

Then tell them to back off two miles and open their peepers.

Today’s Thought
And the light shineth in darkness; and the darkness comprehendeth it not.
— New Testament: John i, 9

Boaters’ Rules of Thumb #22
Bosun’s chairs. The golden rule when going up the mast in a bosun’s chair is this: never trust anybody else. Check everything yourself. Have a back-up halyard. Prefer rope bindings to metal shackles; rope is more honest. And the rule once you’re up there is simple: don’t drop any tools. Crews on deck just hate that.

Tailpiece
Exhaustive intensive researches
By Darwin and Huxley and Hall
Have conclusively proved that the hedgehog
Can scarcely be ravished at all.
And further industrious enquiry
Has incontrovertibly shown
That this state of comparative safety
Is enjoyed by the hedgehog alone.