It’s hard to believe, but nearly every day within the narrow confines of the Houston Ship Channel (HSC), massive commercial vessels (some in excess of 80,000 deadweight tons) engage in a hydrodynamics dance face off. When two of these vessels meet bow to bow within the HSC (one heading inbound, the other outbound), they head directly at each other generally closing at a rate exceeding twenty knots (about 23 miles per hour). At a separation distance of about one-half mile, each turns four degrees or so to its starboard (or to the right for landlubbers out there). When both bows start to pass each other, the Houston Pilot aboard turns back to port (or left) to bring his or her respective vessel parallel to the other, and then as each vessel passes the other’s stern, turns further to port and then back to starboard to resume transiting down the center of the narrow HSC.
If you think that’s easy, consider that the current breadth of the HSC capable of handling deep draft vessels is about 530 feet and 45 feet deep (with twelve-foot-deep-barge lanes 200 feet wide on either side of the HSC), and wide-bodied tankers (Panamax class) are up to 165 feet wide. So when side by side during this maneuver, there is not much room to spare between two such vessels. The Houston Pilots’ guidelines permit two vessels to meet when their combined widths do not exceed 310 feet (and 270 feet further up the channel). The remaining 220 feet or so has to buffer the two vessels from striking each other and also protect each from coming too close to the respective bank on its starboard side. The HSC is the only truly two-way channel for merchant vessels of this size in the United States, which allows the port to maximize commercial cargo throughput.