The Flying Phantom capsized in thick fog while towing a cargo vessel on the River Clyde near Glasgow.
Captain Stephen Humphreys, 33, and Eric Blackley, 57, both from Gourock, Inverclyde, died along with Bob Cameron, 65, from Houston, Renfrewshire. Clydeport Operations Limited was charged with breaching health and safety laws following the incident. It denies the claims.
The company, based at Robertson Street, Glasgow, will go on trial at the High Court in Edinburgh on September 22.