Global orders for new ship construction last year totaled 1,423 vessels, adding up to slightly under 20 million gross tons, a 17 percent decline from 1990.

Officials of the Japan Ship Exporters' Association said last week that during the first six months, worldwide orders for new ships were sluggish at only 665 or 8.7 million tons, a decline of 47 percent compared with the January-to-June term of the previous year.But they reported that new shipbuilding orders in the second half of the year picked up, covering 758 ships overall at 11.29 million tons, a gain of 30 percent against the same months of the preceding period.

The increase in new ship orders, association authorities said, was due to a significant increase in contracts placed with South Korean yards during the final six months of the year. These orders covered 79 vessels at a total of 3.94 million tons, 3.7 times the volume of the first half of the year.

In Japan, the association said, the nation's yards received new shipbuilding orders at almost the same level throughout the entire year. Orders amounted to slightly more than 4 million tons during each half-year term.

The final total for 1991 came to 556 vessels for an overall figure of 8.12 million gross tons, down by 27 percent compared with the previous year.

As a result, Japan's share of the global market for new ship construction fell 6 percent from the 40.6 percent of the preceding year.

In contrast, according to the association, South Korean yards in all of 1991 won orders for 114 new ships totaling over 5 million tons, down by 14.5 percent against the preceding 12-month term. But Korea's global market share jumped by 1.3 percent from the level of 1990 to a 25.1 percent share.

During the same period, Western shipbuilding yards all together received orders for 331 vessels or over 3 million tons, off by 27 percent compared with the preceding year. Their share was only 15.5 percent of the world market.

However, the association reported that, on a compensated gross tonnage basis, Japanese yards were awarded new shipbuilding orders totaling 4.48 million compensated gross tonnage, providing a share of 37.7 percent of the global market.

On the same basis, South Korea's share at 2.22 million compensated gross tonnage produced an 18.7 percent figure. Western shipbuilders during the same period registered a 20.4 percent share of the market at 2.43 million compensated gross tonnage.

But in terms of gross tonnage, Japan had the largest backlog of shipbuilding orders of any other country at the close of the year at 15.7 million tons, according to Lloyd's Register of Shipping.

South Korea had the second largest amount of ships on order at the end of 1991 at 9.4 million tons.