The worst part is that it doesn't even have two identical sides. To do this in Smedit. You must select all (It will create a box around the ship hull). Then look at the start X and end X to do the math to get exactly half and then use the select specific box to put that number into the start X box. Copy that half>flip sides by adding a - to the end X number>delete>paste>reflect. Adjust as needed.