The chief mate of the 605-foot coal freighter Marine Electric testified today that the ship's pumps were incapable of emptying water apparently pouring into the vessel's cargo area through rusted and warped hatch covers before the vessel sank on Saturday, killing 31 men.

Robert M. Cusick, 59, a merchant mariner for 41 years and No. 2 officer aboard Marine Electric since 1978, also told a marine board of investigation that the ship's hull had recently received a small "jagged hole," apparently when it was struck by a bulldozer. The hole was temporarily repaired with a cement patch that was uninspected by authorities and which may have come loose during the ship's final hours, Cusick said.

"You'd wonder how they could weld patches to it," Cusick said of the nearly 40-foot-square hatch covers. "The metal wasn't thick enough." Confirming the testimony of another surviving crewman, Cusick said the covers were warped and wouldn't seal, had improper gaskets, lacked wedges to force the panels together in a watertight way, and had only half the securing attachments they required.

Cusick, who wept openly during his testimony before the Coast Guard and National Transportation Safety Board, said he had suggested repairs of the deck and hatch covers to the captain, and even drew up sketches of the rustiest sections to use as a guide. But though he said he believes the captain passed the requests on to the ship's owner, Marine Coal Transport Corp., repairs were not made.

Scaley holes also were developing on the deck, Cusick testified. "You'd kick some rust," he said, and a hole would show up. Some of these were patched recently with epoxy-type glue, he said.

Cusick was one of only three crewmen to survive the capsizing and sinking of the converted World War II tanker in cold, stormy seas off Chincoteague. He described his lucky find of a swamped lifeboat as he bobbed around in the bitter water, but he broke down and cried as he ended his testimony.

With his wife watching, Cusick raised his forearm upright and said the vessel "went from a position where I was standing on the deck, and then she went like that"--and Cusick's arm collapsed to a horizontal position. In a hoarse voice, he repeated, "She went like that."

Coast Guard Capt. Peter Lauridsen immediately closed the hearing for the day and shortly afterward announced that Cusick had been advised by his doctor in Boston to get medical care immediately. It was unclear whether he would testify further on Friday.

The Marine Electric was bound from Norfolk to Somerset, Mass., with a load of pulverized coal when she went down. Cusick and seaman Paul Dewey, another survivor who appeared in Wednesday's opening session, testified that the ship's hatch covers were full of holes and that she was taking "green water" over the bow from heavy head seas and began to sink "by the head" as water flooded the bow.

Cusick said there was no way to remove water from the cargo holds if it got in through leaky or collapsed hatch covers. He said the ship originally had perforated plates at the bottom of the holds, allowing water to run down into the bilge where the pumps were, but that when Marine Electric switched from carrying grain to coal, the plates were replaced by solid ones to keep coal-fouled water from clogging the pumps.

Despite her apparent flaws, Marine Electric had a current Coast Guard certificate of inspection which was to expire in June. She had been due for drydocking this month but had been given an extension to April. Coast Guard officials said such extensions are common.

Cusick said extensive work was done on the hatch covers during the last drydocking in February 1981, but that the hatches fitted badly and still leaked after the work was done. He said when the vessel was carrying grain to Israel in the last two years, he had the crew jam tarpaper into cracks and holes and coat the hatch covers with 175 gallons of roofing tar to keep water out on the three-week voyage.

The chief mate was sleeping in his quarters during ship's final hours, unaware of the tragedy unfolding around him. He said Capt. Philip Corl summoned him to the bridge at 3 a.m. and told him the ship was "settling at the head."

Cusick helped organize lifeboats and rafts and mustered the men for possible abandonment. He said the starboard lifeboat was swung out on davits and men were launching it "shortly after 4 a.m. when the ship suddenly rolled onto her side.

"It was like the sound of water going out of a tub only magnified a million times," said Cusick. He was pushed underwater but swam along a railing until he bobbed up. An hour later he came upon the swamped lifeboat and climbed in. He lay down in the water, he said, because it was warmer than the frigid air.

"I heard cries, all sorts of groans and cries," he said. Cusick called, "Lifeboat here, lifeboat here," but no one joined him. He was rescued by a Coast Guard helicopter after dawn.

Coast Guard divers checked the Marine Electric where she lay in 120 feet of water Wednesday and found the ship in two sections 100 yards apart with large amounts of coal between.