Following her 7th place in the 1969 Olympics, Sperry Joanna Jones Rademaker continued to compete. She was a national champion at the 1973 United States Canoe Association (USCA) National Championships, held in Marinette, Wisconsin, winning the Women's 13-mile race in a C-2 with Janet Streib, with a time of 1:59:26. At the 1974 USCA Marathon Race in Waco, Texas, she won third place in the C-2 Women's Cruising (20 miles) with race partner Iva Sawtelle, with a time of 3:09:41, and placed 5th in the C-2 Mixed Cruising with race partner and husband, Jack Rademaker, both residents of Floral City, Florida.
In 1975, Sperry and husband Jack ranked 8th in the C-2 Mixed Couples USCA National Race on the St. Josephs River, with a time of 2:35:22. The race ran from Constantine, Michigan to Bristol, Indiana. At that same race, Sperry placed 2nd in the C-2 Women's Competition Cruisers with Carol Davis of Winnetka, Illinois, with a time of 2:39:23. The following year, she raced again at the USCA National Championships with Carol Davis on the Little Miami River in Milford, Ohio, to again place 2nd in the 20-mile C-2 Women Cruisers with a time of 3:02:15. She also garnered a 7th place with husband Jack in the C-2 Mixed Couples (also a 20-mile race) with a time of 3:08:02.
In the 1977 USCA National Championships, Sperry took up her Olympic K-1 boat to place 2nd behind Janet Streib, with a time of 2:06:56.
Sperry won the C-2 Women's event at the 1978 USCA National Championships in St. Charles, Illinois with Connie Barton of Homer, Michigan. [1]
By 1987, Sperry and husband Jack Rademaker had been winning athletic trophies and medals for more than 25 years. The Floral City residents had amassed nearly 400 prizes in canoe and kayaking, triathlons and table tennis. [2]