October 2003

The front of the craft looked like it could do with additional T-section triangles at the 45deg points, so I made up some more and welded them in. One of the drawbacks of space frame construction is that ideally you want to keep the panels on as much as possible to prevent the frame from warping when its being welded, but you also need access to the area that needs welding. This meant I needed to "move" some of the fixing holes in the panels slightly. They are 6.5mm diameter, so if warping causes them to move a millimetre then they were not going to fit any longer. Maybe it would have been better to have welded up the entire frame, using steel clamps to prevent warping, and then clad it all in sheet after the welding had been completed. Well next time (!) I’ll know better.

At this point, all of the panels (except the big bow planing section) have  been adjusted and they all fit well.

The floor panel was cut from a single sheet of 2m x 1m. Unfortunately, as the floor is 2.1m long and 0.85m wide, it is made from two pieces – the main floor panel which is 2.00m long and 0.85m wide, and the rear strip which is only 100mm "long" and 0.85 wide. These two pieces needed to be butt welded together. So I tack welded the rear section to the main floor panel, then ran a few beads top and bottom to seal it properly – remember this is the lowest point in the hull, so it is most prone to leakage when the craft is floating.

New bow planing panel
I wasn’t happy with the bow planing surface. It’s a complicated panel, and it didn’t really fit well enough, so I remade the entire panel with a deeper section to allow a better join to the front of the floor. It took a bit of fiddling – fit it, take it off, trim it, put it back on, take it off… But I was a lot happier with the second version.

More TZR action
It's sort of a shame breaking up the bikes, but all of the parts will be sold on. The second bike will provide spares - hopefully I'll be able to build up a complete replacement engine, and just drop it into the hovercraft if the main engine has any problems.

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