Can't speak to prop pitch, don't know boat and load. Resonant vibration is caused by motor vibrations coming through the mounts and transom. If the prop is properly "balanced", that is, all blades have the same shape and weight, no additional vibrations occur. Different prop "bites" due to pitch changes do not cause vibrations, hence no resonance. We have a C-D 22', with a 2022 DF 90 A turning a 3x13.5x15 that came with the boat. With a fairly heavy vacation load we got only 5100+ RPM WOT, which is too low, and also had cabin resonant vibrations around 4000 4500. After changing to the warmer (71 C) thermostat, we noticed that after a few minutes the cabin vibration disappeared. The only way I can understand this is that the the engine warmed more, got out of the warm-up (fuel enrichment) cycle and ran smoother. Also, max RPM went from 5100 to 5600, GPS speed from 21 knots to 24 knots. Only one run. Note: GPS speed is affected by smoothness of the water, current, wind. The engine had a 60 Celsius thermostat and kept getting excessive fuel into the oil. Changing to a 71 C stat seems to have fixed the problem, though we have only 9 h with the new one. Al Baensch 541-416-3695Hello again, We did repower with the Suzuki df 90. Going through the break-in. Wondering what prop pitch is most common? Also wondering if prop pitch will affect resonant vibration through the boat?
Appreciate any thoughts.