Hard to see and track electronically, warships can be perilous in crowded waters

Hong Kong

THE tropical sky off Singapore was utterly dark when an oil tanker ploughed into the side of the US destroyer USS John S McCain before dawn last Monday - but the moonless night may have been only one of the reasons that the tanker's crew may have had trouble seeing a warship in their path.

Hard to see and hard to track electronically, naval vessels have long posed special perils to night-time navigation. That has proved deadly this summer in crowded waters such as those near Singapore and Tokyo, where another US warship, the USS Fitzgerald, was struck by a cargo freighter under a waning crescent moon on June 17.

The issue has prompted growing alarm in the commercial shipping industry - which has started warning merchant vessels to be extra careful around warships - and in the US Navy.

"There have been four this year for the US Navy, and the Singapore navy has experienced one or two" collisions with commercial ships, said Captain Raymond Ambrose, president of the Singapore Nautical Institute. "We need an attitude of defensive driving out at sea."

Naval ships, designed to avoid detection by enemy fleets and aircraft, are exempt from an international requirement that vessels automatically and continuously broadcast their position, course and speed.

They tend to have fewer lights than many commercial vessels, making them harder to pick out. They are painted grey to blend into the sea during wartime, but become even more difficult to spot at night.

And a growing number of modern naval vessels, including the John S McCain, are designed to scatter incoming radar signals so that they are less detectable.

The Maritime and Port Authority of Singapore told The Straits Timesthat the government's vessel traffic information system did not know the John S McCain was there until the tanker, the Alnic MC, carrying 12,000 tonnes of fuel oil, delivered a crushing blow to the warship's left side.

The Singaporean agency told The Straits Times that it had not detected the destroyer on radar and that its traffic information system had not picked up data on the ship.

In addition to radar, traffic information systems rely on data from the Automatic Identification Systems that all but the smallest commercial vessels are required to use to broadcast information about their whereabouts.

Military vessels typically carry the systems but often turn them off because the captains do not want to reveal so much information.

The difficulties with spotting naval vessels are amplified in busy waters - and those around Singapore are among the most crowded in the world because the city-state lies at the entrance to the Strait of Malacca, through which nearly all of East Asia's oil imports and a large share of its seaborne exports move.

The congestion prompts military and commercial crews to turn off the early warning systems that alert them to potential collisions, said Captain Harry Bolton, director of marine programmes at California State University Maritime Academy and a merchant marine officer who has traversed the waters near Singapore dozens of times.

Modern ship radars automatically calculate the closest point at which other vessels will approach them. The ship's officers program the radars with a certain radius - typically one or two miles - and if any other vessel passes inside that radius, a beep begins sounding on the bridge.

The beeping can be switched off only when someone on the bridge hits a button to do so, acknowledging that the warning has been received. But bridge crews commonly turn off the systems near Singapore because other vessels are frequently less than one mile away, so the beeping would be almost continuous.

But ships such as the John S McCain, a Burke-class destroyer, are considered among the Navy's best examples of vessels with a smaller radar signature, according to several former officers. They are low to the waterline, with equipment masts tilted to the ship's stern, rounded edges and no large "citadels" rising high off the deck, like those on cruisers.

While commercial vessels traversing the Strait of Malacca illuminate their hulls and the waters immediately around them so that they can spot any pirates who may be trying to climb aboard, heavily armed naval vessels with large crews have little to fear and are less lit up.

Sometimes they appear like shadows moving among immense freighters resembling bright Christmas trees.

Many commercial shipping experts say that the difficulty of seeing navy ships is just part of the picture.

They suggest that the John S McCain, with its powerful engines, advanced electronics and nimbleness, should never have moved into the tanker's path, and they have been asking whether steering difficulties or poor bridge communications aboard the destroyer may have been factors. The navy has said the ship's steering system showed no signs of failure, though it has cautioned that the cause of the crash is still under investigation.

Aboard the John S McCain, "you've got power and manoeuvrability - if you want to get out of the way, you can do it pretty quickly", said Arthur Bowring, who retired in November after 20 years as managing director of the Hong Kong Shipowners Association. NYTIMES