After burning out three heater elements in a day, I got the bugs out of my steam generator. I raised the water level to 2/3 of the riser pipe, and no problem. Also tried to steam my lower transom bow in a uninsulated plastic pipe, without much luck.
Got some 1 1/2" aluminum sided "Styrofoam" to build a proper box and getting 211-212 Fahrenheit (99-100 dgr. C) in the box. With blocks screwed to the workbench, I have no problem getting the right curve. Though I had to cook the piece 3 times, with overnight soaking in between, to get it the way I wanted. You live and learn......
The upper transom bow cooling off: