D.C. teachers overwhelmingly ratified yesterday a new three-year contract that would require them to work longer hours and tie their pay raises more closely to their job performance.

The teachers' union voted 1,209 to 385 in favor of the contract, which would also give teachers a 21 percent pay increase over the next three years.

Washington Teachers Union President William H. Simons said the voting turnout was "much higher" than it was three years ago when teachers ratified their contract after a bitter 23-day strike. He added that more than 400 ballots were not counted because the voters did not follow the proper procedures for voting.

"I am certainly grateful for the overwhelming support the teachers have given to the negotiating team," he said.

Simons said the D.C. Board of Education must hold a public hearing on the contract within the next few weeks. He said the board probably will vote at its April 21 meeting on whether to approve the pact.

Many teachers had complained about provisions in the new contract that would require them to work a half hour longer each school day and four more days during the school year. Under the new provisions, teachers will arrive at school at 8:30 a.m. and leave at 3:30 p.m. The additional school days would come in periods when the children are not in school.

The contract also requires that teachers be rated better than satisfactory in their sixth year on the job to receive a scheduled pay increase then.

A joint union-school administration committee will be set up to determine what criteria will be used to decide when a teacher rated "very good," "outstanding" or "satisfactory." Currently teachers need only receive a satisfactory rating to obtain their pay increases.

The contract gives the union greater authority to protest the ratings that principals give teachers in their annual performance evaluations.

The union also won the right to charge nonunion members half of the annual dues that all union members now pay.

The contract gives teachers the chance to sell back to the school system as many as five days of unused sick leave each year in return for five days pay.

Board member R. Calvin Lockridge (Ward 8) predicted the board's speedy approval of the contract. However, Lockridge criticized the union leadership for "short-changing the workers" because the contract contains no job security clause. He said he believes the teachers are "not clear as to what is taking place," but added that he would vote in favor of the contract since the teachers have ratified it.

Board President David H. Eaton said he was "very happy" that the teachers accepted the contract and said he thinks the board also will approve it.

School Superintendent Floretta D. McKenzie could not be reached for comment last night.