Originally Posted by Spike
Just looking at your above post & you say your pushing a 19" alloy prop with a Suzi DF70 on a 4.7ish boat.....what are your rev's at WOT? Im running a 14" stainless with a Yam 60 on a 4.8 boat & not hitting top revs but i get v-good all round performance, i can only get to top rev's with an alloy 14" but that gives me poor 'out of the hole' performance but great top end, good if the sea is mirror flat but crap in a big sea. Just sounds to me like your well over proped on your boat currently......i could be wrong though but it would be interesting to know what revs your pulling WOT & your current top speed before you puchace the new prop.
This prop science seems to vary a lot . My max recomended rpm is 5800
The boat came with a 17" pitch fitted . With that prop it would pull 5800 at 36mph loaded with 3 people full fuel etc but it was a bit lively with less load and tended to over rev a little .
I then fitted a 19" pitch which gave more relaxed cruise but would only pull 34 mph at about 5300 rpm same load .
From that I figured an 18" pitch would be ideal ,but an 18" isn't available . Iam now waiting to try the original 17" prop which I has been re pitched to 18
My thoughts with the stainless 19" that is on offer were that if stainless gave better performance it may just do the job allround and I would also have a spare prop or two. Its just expensive trial and error it seems .
Not sure what dia your prop is mine is 13 1/4 " maybe thats the difference .