SUEZ, Egypt—Two additional tugboats sped Sunday to Egypt’s Suez Canal to aid efforts to free a skyscraper-sized container ship wedged for days across the crucial waterway, even as major shippers increasingly divert their boats out of fear the vessel may take even longer to free. The massive Ever Given, a Panama-flagged, Japanese-owned ship that carries cargo between Asia and Europe, got stuck Tuesday in a single-lane stretch of the canal. In the time since, authorities have been unable to remove the vessel and traffic through the canal—valued at over $9 billion a day—has been halted, further disrupting a global shipping network already strained by the coronavirus pandemic. The Dutch-flagged Alp Guard and the Italian-flagged Carlo Magno, called in to help tugboats already there, reached the Red Sea near the city of Suez early Sunday, satellite data from MarineTraffic.com showed. The tugboats will nudge the quarter-mile-long Ever Given as dredgers continue …