Thursday's order applies to 64 ships in southeastern Virginia. Twenty-seven ships are moving out to sea, beginning at 8 a.m. Another 28 are being moved to other places such as repair shipyards that are safer than the piers at Norfolk.
Nine ships are already at sea.
The Navy says ships that are under way can better weather such storms. It also will help protect piers from being damage.
Forecasters have yet to pinpoint where the hurricane will make landfall. It's currently a Category 3 storm with winds of 115 mph (185 kph).