Couch first arrived in Oregon in 1839 as a merchant sailor, hired by Cushing & Cushing to sell their wares in Oregon City. He'd traveled from the east coast in the Maryland up to Oregon City]] in order to do this, but met with no success, having been forced out of the market by the Hudson Bay Company. He eventually traveled back to the Sandwich Islands (now Hawaii), where he was forced to sell the Maryland in order to travel home. Cushing & Cushing decided to try again, and sent him out in the Chenamus, a bark that he had overseen the construction of, and had named after a Chinook Indian chief he had met. On this second trip, he found that the Willamette River was difficult to navigate above the Clackamas and the Ross Island Bar, and determined that Portland was the "head of navigation".