Yep, he does go on; when I call him I ask my current question and then eat a sandwich. I must admit, his spiel is sprinkled with pearls of wisdom, as he goes on and on and on I get answers to questions I didn't even know I had!
In person he's much more personable, same tone, volume and speed but he brings you behind the counter back into the shop area and really lays out how he does what he does. I like this much better than the "it's a mystery, trust me" kind of business people.
My journey was with two propellers and many many steps over years. I started by depitching the stock 17 X 15 one pitch at a time, getting 200 RPM back each deptich as folks said I would. Ended up with it depitched to 17 by 13, (the maximum of two pitches) and it decupped from .105 to .060.
At that point everyone, Valley, Andrew, Acme and Pacific Marine, the boat repair shop next door to Valley, said there's something else at work here. So I removed the strainer from the fuel pickup in the tank, send my ECM away to be read, had Pacific Marine read my ECM static and while underway, (they had to get the software, kudos to Andrew!) and all was well there.
Then everyone looked at me and said: How much weight have you put on that boat? Why don't you just take it off and see what happens?
So I did and made my WOT RPM just fine, I also weighed my gear as it came off and it totaled in the high eight hundred pounds! Who knew?
A second, damaged 17 X 15 I picked up along the way lent itself to having circumference taken off as it either needed repair on the leading edges or they could be removed. So we diptched and decupped it like the first one and took off circumference 3/4" at a time as as the weight went back on. I'm now running a 15.5 X 13 and make WOT RPM just fine.
Overall, once I accepted this "law of the universe" it was easier to reverse engineer my way to nirvana:
"Whatever the application (weight) the vessel must be propped to achieve correct RPM at WOT."
Here we also have the helpful "load to throttle" data too, my %s got closer and closer as I "lowered" my props.
Simply put, you have to adjust your propeller appropriately to the vessels current load out so as not to stress the drivetrain throughout the RPM range.
As with many folks here on the 'Nuts, I really really struggled with accepting the inevitability of weight decreasing performance. Fuel, (525 lbs.) water, fresh and black (900 lbs.) gear (880) and folks (400) adds what, 2,700 pounds in my case? On a boat that starts at 5,700 ish that a 50% increase in weight?
If I had it to do over again (20 20 hindsight) I'd buy a 17 X 13, (the lowest pitch three blade 17 Acme makes I believe) slap it on and see what amount of RPM increase you get. Should be about a 400ish increase from the 17 X 15 the boats come with. Then you'd also have the ability to depitch this prop to 17 X 11 if you need to, picking up another 400 RPM I believe.
I've always run at a maximum of about 3200 and now you can really hear/feel the engine "settle" in noise/vibration; something it didn't do at 3200 when my prop was "too tall."
See, now I've gone on and on and on like the Valley guy, hopefully condensing my two years of work and giving you some insight on what your options are. rich
