DUBAI -- In the dangerous 550-mile waterway of the Persian Gulf, wily tanker captains use an imaginative inventory of tricks to dodge attacks by Iran, from masquerading as "unsuitable targets" to faking protective convoy formation.

But the deceptions can boomerang, according to regional shipping sources, with discovery bringing swift response by the watchful Iranians.

"The Iranian Navy would actually hunt for the ship which, completely contrary to its aims, would have turned itself into a target," said one shipping source. "It just makes them more angry than ever."

It happened recently to a Kuwaiti oil tanker that tried to pass itself off as Romanian.

The likelihood of attack for some ships has increased since the United States and other countries started protecting their own merchant shipping or, in the case of U.S. warships, reregistered and reflagged Kuwaiti tankers.

About 80 foreign warships are in the gulf region on escort, supply or mine-sweeping operations. Kuwaiti ships have been particular targets of Iran because of their government's support for Tehran's enemy in the gulf war, Iraq.

Neither the Iranian navy, operating from land bases such as Bandar Abbas, nor the Revolutionary Guards in small speedboats based on gulf islands, attack ships under military escort.

"So in effect the American, Soviet, British, French and Italian navies, by guarding their national merchants ships, are increasing the likelihood of attack on those vessels which are not escorted," the source said.

"The pool of ships liable to attack is made smaller so their captains have to scramble to try to fend off the attention of the Iranians."

Radio silence is standard procedure, so Iran's radio monitors cannot pinpoint their position as the ships try to slip safely through the seaway.

If they have to talk to their agents on the gulf Arab coast, the radio operators use predetermined and frequently changed codes to mask their identity.

One ploy used by the tanker captains to dodge attack is to tag onto passing convoys of escorted ships, hoping the presence of warships will give them cover.

But the Iranian navy, which checks unescorted ships in and out of the gulf, asks the convoy commanders which vessels are under their protection and which are not.

"Recently an American convoy told an interrogating Iranian frigate that a Japanese tanker tagged on was not under its protection," said a source.

"But the convoy commander warned the frigate that any action taken against the Japanese ship would jeopardize American vessels because of its close proximity to the convoy."

TheU.S. Navy, by law, can protect only ships flying the American flag.

Other merchant ships' captains cooperate in another ploy.

They sail together in groups, usually in single line, to give the impression on radar they are a convoy under military escort.

Or they "dodge" from one warship to another up and down the gulf, hoping the military vessels' proximity will deter attack.

The Iranian Navy checks ships to prevent war material from reaching Iraq but ignores escorted ships from the Soviet Union and France, Baghdad's chief arms suppliers.

Revolutionary Guards carry out most of Iran's attacks on tankers, based on a policy of one-for-one retaliation for Iraqi attacks on Iranian ships.

In waters where more than 400 ships have been hit since the "tanker war" began in May 1981, even legally dubious dodges are seen as worth chancing by some captains.

Some have falsified the name and port of their vessel, adopting a nationality which they believe will make them less liable to be a target.

On Nov. 26, an Iranian frigate pumped about 20-mm shells into the 86,094-ton Kuwaiti tanker Umm Al-Jathatheel, whose crew had painted out its name and adopted the identity of the Romanian tanker Dacia.

The real Dacia was docked in Romania.

Nevertheless, the Umm Al-Jathatheel was barely scratched and continued on its way to Italy.

Shipping sources said a tanker sailing under a false name was breaking international maritime law.

The owners of the Umm Al-Jathatheel, the Kuwait Oil Tanker Co. (KOTC), said it had not instructed the captain to pose as the Dacia.

But KOTC chairman Abdul Fattah Al-Bader said the company took full responsibility for any action of its captain or crew.

The sources said the fake-name practice was not believed to be widespread.

One said he knew of two other ships that had sailed the gulf under a false name during the past year.

"First, since it's illegal, sailing under a false name and country of registration could affect the insurance cover of the ship," said one source.

"Secondly, the Iranians have sources of information in all gulf ports, and their navy will get to know about any ship changing its name," he said.

He added that Iran's Navy would hunt for such a ship.

"Thirdly, the Iranian Navy is too smart to fall for such a stupid trick."