Nice job, right on the moolah. I'd just add that it'd be fantastic to get a GPS and plot your speed vs. RPM with BOTH props. That'd be a really nice test to see actually what difference a 1" pitch reduction will do.
To tell you the truth, there have been some reports here that make me doubt the concept that top speed will always be reached by the prop that allows you to get to redline 6KRPM. What it will get you is the 'right' prop for general use at a given set of conditions - you don't have to worry about overrevving the engine while on a speed run, and you don't leave any RPM unused. We don't care about top speed usually, but it will mean that your RPMs and torque will be meatier in the region we care about (20 to 30MPH).
>>>all the following is pure wild a$$ speculation and all references to props are old school stainless like mine, not the ACME and XMP 3-blade props<<<
If you used this as a runabout and wanted to optimize for a lot of open-water cruising, you'd probably want to get RPMs down really low and would leave that SS 4-blade 13.5 on it. Your hole shot will suck and I can't even speculate on top speed...
If you had a thousand pounds of sound system like SHAWN, or lived in the Himalayas like Bitzy, your prop won't be the 'right' prop for general use any more. Your engine won't be able to push the boat at 43 because of extra weight (Shawn) or reduced engine power (Bitzy). Maybe 40's your new top, and maybe that comes at 5500 rpm. It's not the lost 500 rpm up top that matters, it's the fact that even at 20mph, you'll be pushing with less engine power. RPM might actually be a little higher (more slippage), but you'll have to use a higher power setting to do that. To optimize for a 'general use' prop with the permanent extra 1000 pounds or extra power lost to air density, you might need to go with a SS 4-blade 12.5" prop.
Now, if you really want to be a pimp like Cal and always roll with nine guys and eighteen melons and some fat sacs, but still want a boat that'll perform, AND don't care what your top end is, AND you unserstand that you will have to watch the RPM if you do end up in a speed run...then you can prop for the weighted condition. If you plan for 3,000 pounds in the boat at all times, maybe you want to prop so that you can hold 4,000 rpm at 24 mph. This will give you the most torque down low when you need it coming on plane and still let the torque be high enough to hold speed at 24. Let's just say that equates to dropping pitch down to SS 4-blade 11" or 10.5". You'll turn a lot more RPMs and burn a lot more fuel when crusing around the lake light, but what ballasted up, you're gonna be in phat city. Be careful when you drop of your crew, because you'll be at engine redline at 35 or so.
I'm still not sure where that ACME 543 fits in at 13" x 11.5". For those of us with the standard reduction (1.26:1), I think the 543 just ends up being the 'right' prop for general use, aka it allows us to use the full RPM range and is more efficient because of the blade count, area and thinness. It's a little shorter than the stock 13x13.
For the boats with higher gear reduction, the ACME 543 is probably more like a wakeboarding-optimized selection, where the boat pulls all the way to the rev limited, and you turn quite a few more RPM at wakeboarding speeds.
To get a wakeboarding prop on a 1.26 tranny, I'd still think you need to go shorter than the 11.5" that ACME recommends. I haven't tried it, I don't know.
ACME says the 543 is the right prop for each Epic because most of the Epics came with 13x13 props. Some of the Epics came with a higher gear reduction (can't remember if it's 1.46:1) like the SX but used the same prop as the 1.26 S22. This means that the SX came with a wakeboarding-optimized prop from the factory. The S22 didn't, as it was intended for general use.
To get the S22 optimized like the SX, you either have to reduce the pitch of the prop even further below the 543, or change the reduction in the tranny to match the SX (like Capt. Rick did with his.) Of the two options, one must be better, and my guess is that it's changing the gear ratio, but that's just a guess. There may be efficiency issues running much lower than 11.5" pitch, I don't know just a guess.
I would love to see the comparison between GPS speed vs. RPM curves in Rick's S22 at 1.26 and then at 1.46.
