Anyone sucessfully installed pywafo for Python 3 under windows OS?
this is probably a little late in the day to answer. I have a wafo "superficially working" on windows 10 with python 3.7.1: however, so far I have only accessed the wave spectrum models. The recipe I used was 


clone the repo
pip install 2to3
navigate to the cloned folder
2to3 . -w 
copy folder to src/wafo folder to site-packages/wafo
Open cmd.exe or something better e.g. ConEmu
Assuming your python.exe is in your PATH. type ... python -c "import wafo"
Then address each problem in turn... 


There aren't many problems to address if all you need are the wave spectrum models. It took me an hour to hack the source code to access these. If you need to access the whole suite of functionality, continue the approach. You may need to recompile the c-libraries if they are needed. 

Sorry I can't provide a comprehensive list of the changes I made to get wafo to import. Here are the ones I remember


It will complain about "import scipy.lib.six". Change to "import six" (install it)
It will complain about scipy's piecewisepolynomial. Change to PPoly
It will complain some version checks ... set to True as your module versions are no-doubt much newer than the versions 5 years ago.