Tech entrepreneurs and endurance athletes Sami Inkinen and wife Meredith Loring have pushed off from the Monterey Marina in their quest to row 2,400 miles across the Pacific to Oahu.

In a Twitter post, Inkinen, 38, the co-founder of the real estate search and information site Trulia, wrote of their scramble to leave before the weather turns: "Last weather wndw to get out in a mad 48hr scramble to escape CA coast ... if not, row boat for sale on Craigslist!"

The couple left the Monterey Marina at 6 a.m. Wednesday.

In another post from@fatchancerow, Inkinen wrote that he and Loring, 34, had rowed together for 17 hours nonstop on day one. The San Anselmo residents are trying to be the first couple to row from California to Hawaii.

They would be the first couple to make it from Monterey to Hawaii, but not the first rowers to cross the Pacific. In 1976, Patrick Quesnel rowed from Washington state to Hawaii, and was followed in the 1980s by British racer Peter Bird. In 2008, Roz Savage became the first woman to row solo from San Francisco to Oahu in 99 days.

The two are rowing in a 20-foot-long, 5-foot-wide carbon fiber boat named Roosevelt - after the nation's adventuresome 26th president. The boat weighs 1,400 pounds unloaded, and 2,900 pounds fully loaded with food and gear. There is no engine and sail, and there will be no support or chase boats following along.

Inkinen and Loring are using the voyage as a test of their bodies, minds and marriage. But they are also trying to raise awareness of healthy eating and the risks associated with sugar.

Any donations made to their campaign, Fat Chance Row, will go to Dr. Robert Lustig's nonprofit Institute for Responsible Nutrition at UCSF, San Francisco. Lustig is a professor of pediatrics, a widely known antisugar crusader and author of a book called "Fat Chance."

The San Anselmo residents plan to post periodic updates throughout their journey, expected to take at least 60 days, on their website, Fat Chance Row.

Julian Guthrie is a San Francisco Chronicle staff writer. E-mail: davidlewis@sfchronicle.com