For the most part, straight sections are used, and cutting the correct length and mitering the joints of the frame is all that is required to making the frame. Plating is usually straightforward with no compound curves except in the bottom forward portion of the bottom plates. In other words, in metal construction, one need not use a conical section because of material limitations. The framing systems are basically all transverse frames closely spaced, transverse frames approximately double-spaced with longitudinal stringers, and widely spaced transverse webs with closely spaced longitudinal stringers. Transverse frames are either Flat Bars or angles.
Angles are the strongest, lightest, and stiffest, and occupy less transverse space.
The objection to them so often heard is that they are harder to paint. Below this, the use of longitudinals often produces a fairer hull, especially those that are not meticulously lofted. Transverse Web frames are usually T sections and occupy more space than regular frames. It is well to remember when using longitudinals that they are one of the prime sources for the deterioration of the shell plating from the inside of the hull, so limbers must be carefully located to prevent any water buildup. Round bottom construction in metal requires a knowledge of stretching metal, which is not difficult to learn.