Didn't remember it until you mentioned it.
Ah, the heyday of the National Lampoon. It was glorious. I think they're some kind of media thing, now. I didn't look very hard, but I couldn't even find a reference to the magazine on their website.
The "R.M.S. Tyrannic" brochure was one of many great bits by artist Bruce McCall. The "Tyrannic" piece appears in his book "Zany Afternoons," along with many others.