Tony, Sail and Yachting Monthly reviewed a host of props of all different types under different load conditions running forward and reverse a few years ago. The one that surprised everybody including the testers was the Flex-O-Fold two blade folder. It performed as well or better than their three blade and many fixed props from what I remember.
I purchased an Australian Slipstream Seahawk stainless steel three blade folder prior to the article because the Canadian dollar had tanked and I could not afford a European prop at the time. My original prop was too small, preventing the engine from warming up or the boat achieving 4 knots going downhill. The Slipstream does everything I could wish for and been in service for several years. My reason for opting for the three blade was due to having a tricky dock to enter or leave. The boat has performed well at the 2014 Nonsuch Rendezvous and in PHRF races
Ben Hawke was excellent to deal with and was able to match the prop to my Universal 16 engine. I thought it was a minor miracle since my diesel was at least 25 years old at the time and he was not familiar with the engine or Nonsuches.
John Newell
Mascouche 26C 1
Toronto