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  #1  
Old 05-01-2019, 03:57 PM
lj_mastercraft lj_mastercraft is offline
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Large boat (X45) props - with videos

Thought I'd post this

2005 X45. It had the 13.7 x 19.5 prop on it when I got it. I was very happy with the performance (with 10 people on the boat, it had enough low end torque that I would be able to throw people off the boat when accelerating from a standstill)

Problem for me was the top end. Most of what I did was not water sports, but mostly just hauling people around the lake. Couldn't do over 30mph without the RPMs being too high for comfort, even when I had no ballast and just 2-3 people on the boat with me.

Bought a 14.75 x 22 spare prop a year ago, but only a few weeks ago got around to putting the prop on, swapping out the 13.7 x 19.5.

Two things to be aware of in an X45 - you have to remove the rudder, and have to lift the boat off the trailer to get that new prop on. Far more work than I thought would be needed, and thought perhaps I was doing something wrong, so I took it to the dealer and they confirmed.

This 14.75 x 22 prop is incredible. The top end that I was hoping for, as I can now do 40-45mph without hardly breaking a sweat. Times we would have a convoy of boats all heading to party cove, I was always the lagger. A week ago I had 7 people in the boat, and was able to hold 40mph at ~4000rpm.

Doesn't seem to have the same power out of the hole as I remember, but still MORE than enough to pull a wakeboarder out and get on plane even with 10 people in the boat.

There was one time almost two years ago where I had 18 people on the boat (it's rated for 18, but that's very unrealistic) - when another boat broke down and I had to transport them to the marina. With 18 people on board the boat wouldn't get on plane, and it was noticeably struggling, even with its big 8.1L L18. However that was the most people I've ever had on it by 5 or 6, but I can't speak to how the 14.75 prop would perform with this much weight.

Couple of weeks ago, with the new engine past the break-in period, new impeller, fresh check-up from the dealership and functioning perfectly, I decided to open her up for a few seconds - I mean throttle full forward - for the first time since I'd owned the boat. Pulled back when RPMs got to just over 5k (I can count on my left hand how many times the boat has EVER seen 5k RPM), and the speedometer was pegged at 50mph. Now granted, that was a calm day with just me on the boat, and not a lot of other weight (1/4 tank of gas, etc).

I was blown away by the performance. This is absolutely THE prop for this engine. Would have done it when I first got the boat had I known. The engine sounds much better than it did with the older prop, and comparing RPM <--> MPH looks a lot healthier too as it accelerates through the RPM range.

TL;DR: On an X45 with the larger displacement (L18 8.1L), the 13.7 x 9.5 has gobs of low end torque. The 14.75 x 22 has a MUCH higher top end speed. I didn't think this boat could see 45mph, but empty and on calm water, it does it easily.

Video of the new prop below:
https://youtu.be/QEaRSrwwSjg

** Disclaimer: GPS verified to 30mph, but not past that.

Last edited by lj_mastercraft; 05-01-2019 at 04:21 PM.
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  #2  
Old 05-02-2019, 11:28 AM
bobdog bobdog is offline
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I have changed props several times on my X45 without pulling the rudder
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  #3  
Old 05-02-2019, 11:32 AM
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clrussell clrussell is offline
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Those prop pitches don’t sound right. I can’t remember ever seeing anything with a 14x22.

Sounds like a super high pitch prop for such a big heavy boat. I run a 15x13 and wouldn’t have anything less
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Old 05-02-2019, 12:24 PM
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kman kman is offline
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Yeah, the factory prop on mine was a 22 pitch, and while it would run 50+mph, it was hard to get moving with any kind of weight. I now run an acme 1285 which is 14.5x14.25. It gets going no matter what weight i have now, and will run a respectable 44mph. That's at just over 5k RPMs though, but it'll run right there all day long.......if you can afford to feed it.

Also, i didn't have to remove my rudder either.
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Old 05-02-2019, 07:50 PM
lj_mastercraft lj_mastercraft is offline
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Not sure how you guys were able to do it without replacing the rudder, but it absolutely would not come off without the rudder removed, clear as day. I thought it was just me, so took it to the dealership, and they confirmed - they had to remove the rudder to change the prop.

Guess it's possible all the new components may have been slightly re-engineered by Mastercraft to be modified slightly from the original fit? That might be the only explanation as to why you can swap props without taking the rudder off. Or perhaps the shaft extends a little further. The entire assembly was replaced two years ago (shaft, rudder, etc). I compared the rudders - old vs new and they were identical, but if you're pulling yours off without issue then it must be a change to the engineering of the replacement parts Mastercraft sent. The prop, sitting at the end of the shaft, is touching the rudder, and still has another 1.5-2" before it will pop off the shaft.

Obviously the size of the prop would have something to do with whether the rudder comes off or not as well I would imagine. But the 13.7x19.5 wouldn't come off. I tried for half an hour, had someone on the boat move the rudder back and forth, wiggled it, turned the prop, but not even close to coming off.

The 22 pitch is just perfect for me, but to be fair, the typical group in the boat is 8-9 people, no ballast, and we're not towing anyone. But even then it moved! With 4 of us on the boat a week ago, we filled the ballasts and wakesurfed and it performed perfectly.

I also would never trust the engine under load at 5k+ RPM. I can count how many times my tach has ever seen 5k

So I guess it does depend on what you're doing with these boats. For just hauling people, I think the 14.75x22 is perfect
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  #6  
Old 05-02-2019, 08:46 PM
37tr3n5k 37tr3n5k is online now
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I would have never guessed.. I had a 22 prop, but it was on a Baja and was running almost 60mph.
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  #7  
Old 05-02-2019, 11:32 PM
lj_mastercraft lj_mastercraft is offline
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Yeah I fell in love with the 22. Top end speed had always been my only complaint with this boat
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  #8  
Old 05-04-2019, 06:55 PM
Alan-S Alan-S is offline
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Sounds like your shaft was replaced with something a little too long, assuming it was an issue with rudder clearance.
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  #9  
Old 05-05-2019, 12:46 AM
lj_mastercraft lj_mastercraft is offline
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I checked all the parts - they match the mastercraft part. so i'll go with the fact that MC made changes over the 13 years since it went on the boat, and new parts are slightly different
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