Archive | Question of the Week

Tropical (Easterly) Waves

Tropical Cyclones just don’t blow in unannounced.  What eventually becomes a named meteorological event begins as a tropical wave (Bowditch calls it an “easterly wave,” elsewhere it is known as an “African easterly wave”) and progresses from this stage to become a tropical disturbance.  If conditions are encouraging, it evolves into a tropical depression and […]

Continue Reading

Determining Shackle Size

Shackle Size Shackles are a primary means of connecting the parts of rigging systems on vessels and industrial cranes.  In its simplest form, a shackle is a U-shaped piece of metal secured by a clevis pin, screw or bolt at its opening.  Shackles range in size from this extraordinarily large forged wide-body shackle capable of […]

Continue Reading

The Chronometer

Chronometer Error and Chronometer Rate Greenwich Mean Time is invaluable to the navigator and the chronometer is the instrument which provides it. But like any instrument, the chronometer is subject to error. Routinely, candidates for Ocean and Near Coastal deck credentials are required to determine Chronometer Error and Chronometer Rate. This week we will do […]

Continue Reading
20100525_rightwhalebreach

Magnificent Beast

In order to protect the dwindling number of Northern Right Whales, the “Marine Mammal Protection Act” of 1972 mandated that the amazing “Eubalaena Glacialis” be given wide berth by, among others, mariners.  As reported in The New York Times in March 2009, the MMPA was working; the population of Northern Right Whales had increased. But the […]

Continue Reading

Reeving Tackle

Mechanical Advantage Archimedes boasted “Give me a lever long enough and a fulcrum on which to place it, and I shall move the world.” An application of the same mighty principle of leverage is found in the blocks and tackles that are used to lift weights on board ship and in the construction industry. “Give […]

Continue Reading

Great Lakes — Where are They?

In the past, with the exception of examinations specific to Great Lakes’ licenses, USCG “Rules of the Road” questions have not asked for the extended definition of these waters as described in Rule 3(m) Inland. They do now. The mnemonic “HOMES—H(uron), O(ntario), M(ichigan), E(rie), S(uperior)” no longer suffices to answer the questions “What is . […]

Continue Reading

Submarine Signals

Submarine Emergency Identification Signals The US Navy has long authorized certain submarine emergency identification signals.  In the past, these signals could be found in Chapter 1 of a current Coast Pilot.  No more.  Notice to Mariners No. 1, the first publication each year of the weekly NTM includes a section called “Special Notice to Mariners Paragraphs” describing, […]

Continue Reading

Restraint of Rulers

Marine Insurance & the Restraint of Rulers, Princes or Peoples The term in question is found in the Marine Insurance Act of 1906: “Touching the Adventures and Perils which we the Assurers are contented to bear and do take upon us in this Voyage, they are of the Seas, Men-of-War, Fire, Enemies, Pirates, Rovers, Thieves, […]

Continue Reading

Board Feet

Calculating the Number of Board Feet in a Consignment of Lumber Occasionally it is necessary to calculate the number of board feet in a pile of lumber.  The key to the problem is knowing that a board foot is 1′ (long) x 1′ (wide) x 1″ (high).  In other words in every cubic foot of […]

Continue Reading

“Full and Down” Calculations

“Full and Down” describes the desirable but rare condition in which a vessel has all her cargo space filled and is loaded down to her Plimsoll marks.  Achieving the state of “full and down”  requires some arithmetic.  The old examination bank of questions has three “full and down” problems, two of which require elementary algebra.  The new examination […]

Continue Reading

Chart Projections

In 1849, Dr. Samuel Birley Rowbotham published the pamphlet “Zetetic Astronomy: Earth Not a Globe”  in which he asserted that the Earth is an enclosed plane, surrounded by the ice of Antarctica and (somehow) suspended over which are the stars, the Sun, the Moon and the planets.  Nearly three hundred years later, the astrophysicist Neil […]

Continue Reading

ETA

Near Coastal and Celestial examinations for inspected deck licenses over 200 gross tons will often include an ETA (Estimated Time of Arrival) problem. The more interesting of this type are trans-Pacific and therefore cross the International Date Line. The trick to these problems is not to think — not to think about the Date Line […]

Continue Reading

Get Smart, Go Astern

Get Smart, Go Astern In a study published in Psychological Science (May 2009), Dutch researchers determined that “Backward locomotion appears to be a very powerful trigger to mobilize cognitive resources.” The Rules of the Road anticipated this conclusion in Rule 8 by advising that “if a vessel needs more time to avoid collision or assess […]

Continue Reading