Great resource which allows one to get an idea of the issues involved in Tanker safety. Thank You for posting the link.

Just browsed the book and immediately found "the smoking gun" in the preface itself!

Mandate twin screw in the form of two fully independent engine rooms. Under the current system, 99.5% of all tankers, however large, are single screw. These ships are always a single failure away from being helplessly adrift. The book presents evidence, never before public, that there are at least ten total loss of power incidents on tankers every day. Twin screw, properly implemented, would reduce this failure rate by more than a factor of one thousand. Twin screw would also drastically improve tanker low speed maneuverability which is implicated in a number of big spills including the Aegean Sea shown on the cover.