Submarine tiny home: 20 × 5 m hull with rounded ends

The main deck plan is finished and saved as plan.dxf, with preview.png alongside it. I checked the render twice and fixed the clashes I found. One small doubt is left: the bathroom door gap shows in the corridor wall, but its swing doesn't show clearly at preview size. What's in the drawing: - The hull is 20 × 5 m with half-round ends 2.5 m in radius. The curves are drawn as straight segments at 15° steps, so they read as round but aren't true arcs. Exterior walls are 0.15 m and interior walls 0.12 m. - Bow lounge, 11.3 m²: sofa, armchair, round coffee table and five porthole windows. - Galley and dining, 18.4 m²: worktop along the north wall with fridge, cooker and sink, plus a dining table for four. - Spiral stair hall, 8.8 m²: a round stair 1.8 m across, drawn as 12 wedge-shaped steps and marked "SPIRAL UP". - Bathroom, 4.6 m²: WC, basin and shower, entered from a 6.1 m² corridor. - Captain's bunk in the round stern, 23 m²: double bed, two nightstands, a wardrobe and three portholes. - Annotation: grid lines A–F and 1–2, a dimension chain per grid bay, the overall 20 m and 5 m dimensions, floor level, north arrow, title, room schedule (72.2 m² total) and legend. The layers are A-WALL, A-WALL-PATT, A-DOOR, A-GLAZ, A-FURN, A-FLOR-FIXT, A-GRID, A-ANNO-DIMS, A-ANNO-SYMB and A-ANNO-TEXT. Assumptions I took: - The bow points west, so the lounge is at the west end and the bunk room at the east end. - Between rooms I used open passages; only the bathroom and the bunk room have swing doors. - Porthole windows are 0.45 m wide, the galley and dining windows 1.2 m. - Room areas are approximate. - The stair outline is a 12-sided shape and the wedge lines are drawn as very thin walls, because the drafting library has no circle or spiral-stair tool. Expect them on A-WALL in the file, not on a furniture or stair layer. - The conning tower deck above is not drawn.