By John Nelson
Columnist
A recent article in a maritime publication relating how the value of cargo lost off the deck of a ship was
partially covered by the ancient principle of General Average made me recall a course I took decades ago
in the U.S. Merchant Marine Academy.
To refresh my memory on the subject, I found my old textbook on Marine Insurance, and reading it again
brought back more memories. I recalled being a little worried when I learned that we would be taking the
course right after lunch since nodding off in class was not tolerated.
I can’t say that the book was any more of a thrilling read today than it was then, but it did remind me that
Marine Insurance, in a codified form that would be recognized today, is the oldest form of indemnity
known with a traceable history going back at least to the 12th century. And General Average, considered
the origin of Marine Insurance, can be traced back another 2100 years.
The principle originated early in the history of maritime trade in the Mediterranean where shipowners to
increase their profits would allow merchants and traders to keep bringing goods on board until the ship
was dangerously overloaded. If the weather was favorable to the next port, everyone was happy.
But if a gale blew up and the ship started taking on water over the gunnels, it was common practice to
throw cargo overboard – or jettison cargo as it is known in maritime vernacular – to lighten the ship.
To compensate those who lost their goods to save the ship, the principle of General Average was
devised. By this system, the value of the jettisoned goods was prorated over the entire value of the ship
and other cargoes so that all participants in the voyage bore a share of the loss.
My old textbook gives an early example of jettison that occurred during a voyage between Joppa and
Tarshish. It’s interesting that Jonah was a passenger aboard that ship as he attempted to duck out on an
assignment from God to preach in Nineveh.
The book of “Jonah” describes how the ship was tossed about by a mighty tempest on the sea and how
the mariners began throwing cargo overboard to lighten the ship. When it was determined both by
casting lots and by Jonah's own admission that God’s displeasure with him might be the reason for the
storm, the sailors threw Jonah over the side.
Though today no one seems to know the exact location of Tarshish, it’s mention in several biblical
passages led the author of my textbook to estimate that the voyage took place between 800 and 900 BC.
That happens to be just about the time that General Average was recognized in a maritime law code
promulgated by the Rhodians who were then the masters of Mediterranean shipping.
If those dates are accurate, the losses on the voyage to Tarshish might have been covered by General
Average, and if so, the seamen would have had to assign a value to everything jettisoned. I’m not sure if
Jonah was included in that tabulation, but I’m guessing they left out any mention of tossing a passenger
overboard.

Moving ahead about 900 years to the time that the Apostle Paul was being taken under guard on a
voyage to Rome to appeal his case to Ceasar, one can see that little had changed in the practice of
loading ships. The misfortunes of that voyage were likely caused by overloading and the fact that it
started late in the year when winter storms made sailing on the Mediterranean dangerous.
The book of “Acts” relates how during the course of a storm most everything not nailed down was thrown
over the side, and though a good example of jettison, General Average could not have been applied. For
that to be used, a sacrifice of parts of the cargo and ship’s gear would have had to result in the saving of
the rest, but on this voyage, the ship and any remaining cargo was ultimately lost off the coast of Malta.
The textbook reminded me that it was not until the 1870’s that a member of the British Parliament named
Samuel Plimsoll persuaded other members to pass an act requiring markings on the hull of British ships
to indicate safe load lines. The regulation spread to other nations, and today Plimsoll Markings are
displayed amidships on the hulls of all commercial ships.
It’s a curious fact that after devising a method to compensate themselves for overloading losses, men
were content to wait about another 2,700 years before making a serious effort to eliminate the practice.