Tanks & Cab
The tanks on the Shay were made of galvanized steel soft soldered together. There were several leaks that were sealed with additional solder or, in the case of the water tank, caulk. The inside of the water tank was finished with waterproof paint and then truck bed liner spray coating. Much of the bed liner coating has peeled off and at some point one or both the tanks will probably rust and start to leak. The oil tank has a slight weep but not enough to spend the effort to fix.
Wayne Godshall mentioned that he had made tenders with a steel outer tank and an inner tank of PVC. He said he used 1/4" PVC sheets, machined the edges very smooth and then glued the pieces together. I tried the glue route and wasn't satisfied with the results so ended up doing plastic welding on the joints. That worked very well once the process was figured out. The water tank looks like it will hold for at least 20 years which at my age is probably more than a lifetime. I wasn't sure that the PVC was compatible with the fuel oil and couldn't get a good yes or no answer from any of my resources. A little test tank from PVC scraps was tested with gasoline for several days with no noticeable effect. So, also made the inner oil tank of PVC. Later I learned that the best plastic for fuel is polypropylene but the PVC should hold up for a while. If the PVC fails will make a new tank with polypropylene.
The outer tanks were made of 18 gauge steel fastened together with #0 drive screws and 1/16" rivets (1/8" head). The tender tank must support the engineer's seat so it will be reinforced and the top is 1/8" thick (11 gauge).
On the Shay, the tender fill port was near the front which required that the seat be lifted away when water was added --- what a pain. This time I decided to fix the seat to the tender top via a bar stool swivel. The fill port was put toward the rear of the tender behind the seat.
The outer fuel tank and the cab will be one piece that is easily removed to access the electrical components and the plumbing. The shay roof was hinged so that the back could be propped up to access the controls. After a year or so the roof was removed. The Heisler cab will have an open roof.
The links below lead to details of the Tanks and Cab.