The number of vessels being registered under the Panamanian flag continues to grow despite the ongoing political unrest in Panama.

Meanwhile, ship registries in another leading open-registry nation, Liberia, have not risen significantly so far this year.Japan, Hong Kong and Singapore lead the list of countries whose shipowners are increasingly registering their vessels in Panama, said Julio Chanson, director and chief of maritime safety for the Directorate of Consular and Maritime Affairs for Panama.

In March, shipowners registered in Panama 73 new vessels totaling just over 1 million gross tons. That was up from 58 vessels of 609,737 gross in March 1987. The trend continues for April, Mr. Chanson said.

During the present political uncertainties in Panama, Mr. Chanson, who is based in New York, said he wants to assure present and potential shipowners that 'normalcy' is the byword in the implementation of its ship registry program.

Panama has the largest total gross tonnage of vessels registered under its flag, followed closely by Liberia. Flags of convenience, also known as open registries, offer shipowners tax breaks as well as a loophole to hire foreign crewmembers. Both of these can offer shipowners substantial savings.

Liberia's ship registry has not grown significantly since the first of the year, said James E. McGuire, deputy maritime commissioner for Liberia and head of its marine safety department.

Mr. McGuire said Panama's increase of 15 ships in one month may simply be attributable to ship deliveries being made for the months of February and March. He said it is uncommon for political problems to affect the business of ship registries.

Ever since Panama's military strongman Manuel Antonio Noriega was indicted on drug smuggling charges earlier this year, much attention has been focused on whether the political instability would affect ships passing through the Panama Canal. Thus far little impact has been noticed.

Mr. Chanson said politics do not play a role in the registration of ships under the Panamanian flag. The republic's 26 consulates around the world are doing a brisk business in ship registries, he said.

Among the companies with significant numbers of vessels registered in Panama are Taiwan-based Evergreen International SA, Worldwide Marine Inc. of Hong Kong, and Sanko Steamship Co. of Japan.

The Panamanian registry has been in existence since 1925 and has garnered the reputation of being stable, he said.

This is an established system, not one that is being newly created, Mr. Chanson said from his office in New York. Our registry is recognized by all of the main port authorities worldwide, including the United States.

This gives assurance to shipowners when they use the Panama flag that their vessels will trade without delays and with all the assistance and technical advice of the Panamanian registry. We have more than 500 inspectors in more than 300 ports worldwide.

Liberia has 250 inspectors for the 1,700 vessels that sail under its flag. Total gross ship capacity registered in Liberia is 52 million tons, compared with the 62 million gross tons registered in Panama. The number of vessels registered in Panama - which includes tankers, containerships, fishing vessels and passenger ships - totals 1,200.

Mr. McGuire said he has received about three to four dozen telephone inquiries from shipowners in the last few months asking about the possibility of switching their registry to Liberia if the political unrest continues in Panama. Thus far, there has been little or no shifting, he said.

A spokesman at the State Department's maritime desk said little has changed in recent weeks in Panama.

The economy is functioning at a low level because of a shortage of cash. You also have a population generally dissatisfied with the regime that forced the president out, he said, referring to President Eric Arturo Delvalle, who is still recognized by the United States despite his ouster by Gen. Noriega.

Mr. McGuire said he's not surprised about the increase in ship registries in Panama.

Shipowners often feel confidence in a particular (open registry program), almost in spite of what is happening in a country politically, he said.