The hull (including net cutter) probably has no texture assigned to its .obj sub-part.
When you open a unit in Silent 3d Editor each object should have a material assigned to it. Each material/texture will have a unique hex identifier, for example the Nippon Tanker has
0xe697a02f802cb46a for the main/external texture. Note the material ID box in the screenshot... if for example I wanted to add a new lifeboat to the Nippon Tanker, after I added the model in Silent 3d Editor I'd need to copy
0xe697a02f802cb46a THEN click on the lifeboat in the tree arrangement to the left and paste that hex id (
0xe697a02f802cb46a) as its material.
