This image shows a closer view. At this stage I had begun to clean up the MDF supports

This image shows the furthermost support being given the same treatment as in the previous photo. For this fiddly work I had to wrap a piece of 100 grit sandpaper around a cut-down sanding stick to get sufficient access.

For the inner pressure hull to maintain it's curve it had to be supported so that it formed a strong bond.

I used 4.5mm wide by 2.5mm thick plastic strip. The attached photo shows a close up of one of these pieces.

This image shows further plastic strip being fixed to act as inner pressure hull supports.

This photo shows another support fixed in place.

Another image showing the vertical supports.

To fabricate the inner pressure hull I used 0.5mm thick plastic sheet. It took awhile to cut it and file it so that it would dry fit correctly. This image shows the plastic sheet, cut and ready for fitting.

This photo shows the U-boat now back up the right way with first of many 2mm by 2mm square plastic strips glued in place. By careful cutting I could spring it into place so that it formed it's own natural curve to match the inside of the pressure hull.

I chose 2mm square strip as this matched the dimensions of the t-frames [ribs] on the Engine Room and Control Room supplied with the part-works. You can just make out in this photo the ribs in the Engine Room.

Using a schematic as a reference guide I could then calculate the spacing between all subsequent ribs based on the distance between the two datum ribs already fixed as shown in the previous two posts.

Once i knew what the gap would be I fabricated two spacers to match the calculated distance. I made two so that each rib could be placed against them so that they would be parallel to the one before it.

The attached photo shows one of the spacers filed to give me the correct width; 9.08mm.

I worked from each end when fitting the ribs. This photo shows the third rib fixed in place.