Paul Hall, 65, a founder and president of the Seafarers International Union and a blunt-spoken foe of racketeers and Communists in the labor movement, died of cancer Sunday in the Neurological Institute of Columbia Presbyterian Medical Center in New York City.

Mr. Hall helped found the SIU in 1938. He became president of the union, which now has about 80,000 members, in 1957. Until last February, when he retired because of reasons of health, he also was president of the maritime unions department of the AFL-CIO, which comprises 42 national and international unions with a combined membership of about 8 million.

Lane Kirkland, the AFL-CIO president, said the union movement had lost "one of its most articulate and staunchest defenders" with the death of Mr. Hall.

In his professional life, Mr. Hall was concerned about two sides of the same coin: the pay and conditions of work of American Seamen, and the health of the U.S. Merchant Marine, which could provide decent jobs. He played a role in the passage of the Merchant Marine Act of 1970, which provides federal subsidies to rebuild the U.S. fleet, and also helped found the Harry Lundberg School of Seamanship at Piney Point Md., to train young people for careers at sea.

The school was named after Harry Lindberg, the first SIU president. Lundeberg formed the union at the request of William Green, then president of the old American Federation of Labor, to counter what was perceived as growing Communist strength in the maritime trades. Lundeberg selected Mr. Hall as one of his organizers and he was one of the first members of the union.

Mr. Hall, who was born near Birmingham, Ala., first went to sea as an oiler on an American Freighter at a salary of $1.60 a day. He sailed on merchantmen during World War iI and then became a port policeman in New York. In 1948, he began a fulltime union career as a vice president of the SIU.

By that time, he already had established his credentials as an anti-Communist, a position he held for the rest of his life. He once told an interviewer that there " are a lot of reasons not to like commies, but one of the best is they are a bunch of finks. They didn't give a damn about the labor movement."

In the late 1940s and early 1950s, a major problem on the waterfront was racketeering. Mr. Hall and his union gave full cooperation to the New York State Crime Commission and set up penalties, including dismissal, for members who were involved in narcotics smuggling and other violations.

In 1949, an effort was made to frame Mr. Hall by planting a quantity of narcotics in his automobile. In 1954, an attempt to assassinate him was foiled by authorities.

For the members of the SUI, Mr. Hall helped eliminate racial classifications from hiring policies in 1951, established a health fund, and opposed federal regulations that seamen undergo security checks. He fought frequent jurisdictional disputes with the rival National Maritime Union.

Whether on union business or working for one or another of the many civic activities he supported, Mr. Hall, a husky 6-footer, was known as an eloquent speaker. He could be profane or circumspect, as the occasion demanded, but he was persuasive more often than not.

Mr. Hall's survivors include his wife, Rose, of Westwood, N.J., where the family lives, and two children, Max and Margo.