Ships built in Fredrikstad

Can anyone assist me with a ship builder around 1860 or later by the name of Karl Olsen (born 1835 and listed as a Skibsbygmester in one census) who may have been a ships Captain as well who built ships at a site around 300 metre from the shops on the river if you go away from the bridge. Also on the same side of the river or stream.. If there are any relatives of said Karl there is an Olsen reunion in Australia in March 2013 at majorca in Central Victoria Australia. karl was married to Elen Engebretsen and they had Andreas Helfred Karlsen born 1864 and a daughter Engerta born 1861.