I use AutoDesk Inventor, for a single drawing with 1 person doing it you are better off getting a piece of butcher block paper big enough for a 1:1 lifesize drawing. Tanks aren't all that big. That way you can lay the part on the paper you want to use and trace it or reverse trace it as a pattern to cut out a blank. After you go thru a mess of work to create a 3D rendering you can't help but wonder if it was worth all the effort, you could have actually built the damn thing and be looking at it. Now if you have moving parts or doing a structural analysis that is different, 3D rendering is worth the effort.
But a garage floor & a kiel or big paper & pencil is very hard to beat.