>>I later learnt one of our "rival groups" attempted the same thing and it took three phd students working full time for a year to rewrite their code from fortran to C++.

I wonder if there are any transcoders for Fortran to C++? I wonder if there is even a market for something like that? I've written alpha versions of transcoders for C to Java and Java to Objective-C and I think I could do the same for Fortran to another language but why?

Writing a transcoder first is the right way to do it and it should take you a couple of months to do it, especially if you already have some experience with this kind of stuff. Definitely less than a year for a single person. I would not try to translate the code by hand. It would be a never ending project full of bugs.

Edit: Apparently there are plenty of Fortran to C++ transcoders. Here is just one I found during my google search: http://cci.lbl.gov/fable/

No idea how good they work.