I am confused. Page 22 of PCM's owners manual (found on PCM's website) states that the H5 and H6 DI engines are calibrated to operate on 87 octane fuel, that E10 or less is acceptable, that fuel rated higher than E10 should not be used, and that premium 93 octane fuel should be used for optimal performance. To me these statements exclude the use of E85. Perhaps PCM has not updated its website owners manual. If so, that does not speak highly of PCM, and I am and have been a PCM engine advocate for many years.
What fuel are you owners of the DI engines actually using in your boats, and what does your written owners manual say regarding fuel use?
Like @Bruce_Butterfield, I would be shocked if E85 produces more power or economy than normal gas. Apparently PCM engines now are able to use E85, but I wonder if the rest of the fuel system in boats will tolerate it. I am just interested in what is happening in the real world?