It takes money to make money, they say, and sometimes it takes gold to find gold.

Bill Brenner was in the stern of Robert Coleman's charter boat last week, casting furiously into the five-foot seas and bracing himself against the pitch and roll.

"Come on, rockfish," he muttered. "If I have to put platinum on this hook to get one, that's what I'll do."

Platinum? Far-fetched, but not that far from the truth. Twenty-five yards out to sea, bouncing along the hard bottom of Nine-Foot Knoll outside Baltimore Harbor, was a chunk of the bay's most revered delicacy, soft-shell crab.

Brenner and fishing partner Jerry Stanbury had shelled out a charter fee plus $1 apiece for 40 live soft crabs. These crabs, which should have been slowly suateeing in some French chefs kitchen, were now iced down and resting in a neat formation in Coleman's catch box.

From time to time the captain drew out four or fice, their claws grasping futilely in the stiff breeze, and cut them in quarters with a pair of dirty scissors.

The quartered crabs went on the hook, then into the shallow water, weighted down by two ounces of lead. The idea was for a big rock to come along and gobble up the sweet meat.

This costly play, but worth it to most bay fishermen. To many the dream of a big rock on the line has been just that, a dream, ever since Hurricane Agnes and the bluefish invasion swept through and changed the character of the fishery.

Coleman and a few other chartermen out of his home base, Rock Hall, are among a tiny number of skippers who still guide rockfish parties on the bay.

"I'll put you on the fish," Coleman had said as he pulled away from the dock, "but I can't guarantee they'll bite."

Brenner and Stanbury were belivers.

Stanbury had stumbled on the scene the week before when he was cruising in the northern bay. He pulled into Rock Hall for the night and toward evening a charter boat burbled in. When the party finished unloading fish Stanbury couldn't believe his eyes. There were 39 big rock on the dock.

According to Coleman that's nothing unusual. "When the rock are feeding you get one every time you cast," he said. "We've been catching rockfish all summer."

Brenner and Standbury fish every chance they get on their own boats out of Chesapeake Beach, but neither has hit a rock in two years. To them, it sounded like paradise regained.

This time paradise was just outside their grasp. As dusk fell and the lights of busy Baltimore flickered on to the north. Brenner and Stanbury reeled in for the last time. There were three rock in the boat, all in the six-to nine-pound range.

But two had been caught by the skipper, who lucked onto a school passing off the starboards rail, and one by a guest. Stanbury had one on, he thought, but it spat the hook. Brenner's best thrill was a big blue that leaped once, then cut the thick monofilament leader.

The worst agony was a look at the catch box, now devoid of 40 spectacularly fat soft crabs. If the rock weren't feeding, the snapper blues and spot were. These little fish pillaged the baits, feasting almost scot-free as they tore the meat from the oversized hooks.

Coleman was a little chagrined by the poor showing, but he remained optimistic. "They were down there," he insisted. "You could see them all over the depth-finder. They just weren't feeding. A lot has to do with the tide and the time of day. We just hit it wrong."

That's the good news. Now the bad news for Washington area anglers with a notion to try their hand at anchoring on the oyster bed shallows at Nine Foot Knoll.

Even if you're willing to fork over the price of a good pair of boots for a platter of rockfish bait, you may not be able to.

Four spendthrift Washingtonians were willing to try their luck last weekend, but no one had live soft crabs. Not at Woodfield's in Galesville, not at the crab houses in Chesapeake Beach, not on the Maine Avenue fish wharf. Plenty frozen, but Coleman said they won't do.

And the sportfishermen in Rock Hall say the charter skippers have the soft crab market there sewed up.

"Ah, I guess it's back to bluefishing," sighed Brenner. And chances are the next time he sees a soft crab he won't cut it until it's fried golden brown.