Say they have a CAD model with different types of steel/composites for material. If they select the wrong type of material, or the wrong weight for that materia

Say they have a CAD model with different types of steel/composites for material. If they select the wrong type of material, or the wrong weight for that material is used, or the thickness of a material is off by even a slight fraction, then an issue such as this could come up. Considering that there are millions of custom parts to a submarine, it's an amazing feat to ONLY be off by 70 tons.