921 ProXP Prop Question

[dps136]

I have a 2014 Phoenix 921 ProXP with a 250 ProXS, running a tempest 25p, with an Atlas Hydraulic JP. I've tried tinkering with adjustments, but the best I'm getting is about 70mph at about 5600 rpm. With the JP showing 13 on the gauge. If I try to raise the trim higher, or the JP to 15 or 16, it starts to chine. I've tried driving through it, which at the first bump it's controllable. If I bump it higher, it starts to walk even more and progressively gets more aggressive to where I have to pull back on it. That happens around 71 mph. I'm running with myself, I'll have the passenger live well with water, (which helps a little) and the gas tanks is 1/2 tank or less.

I know this boat can do more from other threads I've read.

My question is this: Would I do better with a different prop? If so, what kind?

Also any other recommendations of what to try would be appreciated.

[txbass1]

I don't have a 921, so take it with a grain of salt......but you should be spinning that wheel a lot higher rpms I would think. Is this an analog gauge telling you 5600 or Mercmonitor? What shape is the prop in? Maybe consider sending it to Mark Croxton? Second thing I have learned about my boat is that weight distribution determines a lot when it comes to chine. I have taken a two foot level on the water with me to see how its sitting port-starboard in the water, also considering weight in the front staying to a minimum. That helped a lot.

[dps136]

I'm going off the analog gauge on the dash. The prop is in immaculate condition. Not a ding or scratch on it. On the starboard side I keep all my soft plastics which is probably a good 40lbs of stuff. I've thought about switching those over to where I keep the rods and put the rods in the starboard side, since they weight less. Don't know why boat builders don't do this from the start. But I should still be turning more RPM's, which is why I'm thinking prop pitch/type. I'm thinking of going with a Fury, but should I maintain the same prop pitch or go up or down?

[txbass1]

I would definitely try to get the reading electronically before I went too far buying props and such. You're really only a couple mph off of what people are actually running every day. Keep in mind some of the MPH numbers you see on here are best case scenario. And some just have it dialed in perfectly. You may be able to pick up those couple mph with driving. All my soft plastics are in the port rear compartment. (probably at least 40#). My starboard rod box has all light stuff. (gloves, raingear, pfds, towel, TP, etc.). I'm a pretty heavy fella and that's what I worked out with the level. Also by going with others' opinion on here that Phoenix boats don't mind weight in the stern, but weight in the bow matters a lot. Also have to learn to chill on the trim a bit. On past rigs I have always hammered it out of the hole and immediately started getting it to max trim. I come up much more methodical on trim on my 920. Trim, let speed top out, trim a bit more, let speed top out, trim a bit more.......etc. It's only a few seconds between the bumps, but rig stays a lot flatter and drives much easier. It doesn't take near the trim that my old rig does for peak performance, but I'm running a SHO as well- maybe a bit different.

-And you say the prop is perfect, but I'm pretty sure I've read that Tempest is notorious for coming outta the box different and really wakes up with a blueprint by Mark.

[dps136]

I was coached about being progressive on the trim as well and found that helped. But, still when I get up near the top end of it, typically when the speed hits 70, it starts to walk. Now if I hold it there, I can steer it under controll. But if I bump it again or try taking the JP from 13 to say 15, it really wants to walk and I have to back off.

[Z520C]

I’m running a pro xs, atlas, and a 25 fury. The prop has some years on it and my boat is loaded to the gills runs 70. But this is a 2 mph slower than last year not sure what the deal is but it’s lost some. Plus it has a little chine at the top speed but I’m not so worried about it that I would spend a bunch of money to fix it

[txbass1]

I was coached about being progressive on the trim as well and found that helped. But, still when I get up near the top end of it, typically when the speed hits 70, it starts to walk. Now if I hold it there, I can steer it under controll. But if I bump it again or try taking the JP from 13 to say 15, it really wants to walk and I have to back off.

Have to think some of that is weight distribution related. Costs $0 to figure that out.

[Jeffmcbroom]

Wrong size prop. I have a 15 921, switched to a fury 24p prop last year. ~3" prop center to pad. 5950rpms and 74mph.
I tried to make a 25p prop work for 2 years, glad I made the switch. Hole-shot is even better.

[Farmerman99]

Wrong size prop. I have a 15 921, switched to a fury 24p prop last year. ~3" prop center to pad. 5950rpms and 74mph.
I tried to make a 25p prop work for 2 years, glad I made the switch. Hole-shot is even better.

24p fury or tempest ?

[Fidgetcranker]

The Tempest is not your prop for that boat unless you have Mark Croxton work it. I forget if it has too much lift, or not enough.

Typically, you should be getting 73 mph average speed, alone, with that load, and 5850+ rpm's. That will require a bit of "driving" on your part.
A 25 fury is your prop. Once you get the driving down, you should be at 15 on the Atlas, maybe 16 for optimum performance.
Some use a 4 blade prop to rid the chine, but sacrifice a couple mph.

Not sure if you know, but you don't "drive through" the chine walk. It must be controlled using your steering wheel with small tugs to the left when boat rocks to the right. When done properly, that will center the boat back on pad for a short time until it starts chining again, then repeat with tugging left on steering till she's stable.
This takes some practice and will eventually come natural. You will fix it before it even starts to chine.
Good luck!

[Jeffmcbroom]

Fury

[haus9393]

I was coached about being progressive on the trim as well and found that helped. But, still when I get up near the top end of it, typically when the speed hits 70, it starts to walk. Now if I hold it there, I can steer it under controll. But if I bump it again or try taking the JP from 13 to say 15, it really wants to walk and I have to back off.

You still need more work on driving the boat then and the only way to get better is by pushing the boat to where it gets out of control and learning how to correct it at that given point.

[dps136]

You still need more work on driving the boat then and the only way to get better is by pushing the boat to where it gets out of control and learning how to correct it at that given point.

Seriously??? Let's think about this..... Pushing a boat until it's out of control just to "try to learn" how to correct it makes about as much sense as sticking my finger in a light socket to learn how not to get shocked. If I have to drive the boat like that to get an extra 2-4mph, I'll deal with a slower boat and be safe and alive to come home to my wife and babies.

And if Phoenix designs their boats to have to be driven that way, then I made a wrong purchase. Performance on these near $100k boats shouldn't come with sacrificing safety.

[haus9393]

Seriously??? Let's think about this..... Pushing a boat until it's out of control just to "try to learn" how to correct it makes about as much sense as sticking my finger in a light socket to learn how not to get shocked. If I have to drive the boat like that to get an extra 2-4mph, I'll deal with a slower boat and be safe and alive to come home to my wife and babies.

And if Phoenix designs their boats to have to be driven that way, then I made a wrong purchase. Performance on these near $100k boats shouldn't come with sacrificing safety.

i don’t mean trim it up and keep going until it’s out of control and then try to fix it, by then it’s too far gone to correct. But when you bump the trim and it starts to get squirrelly you need to try and correct it at that exact point and keep trying over and over until you get it. Then gradually you will get to a point when that becomes second nature. Eventually you will be running 40 mph full trim then just punch the hot foot and climb right up to 75mph with just 1 hand on the Wheel. I had a few pucker factor moments when I first got my Phoenix thinking no way can turning a Wheel fix this but I was totally wrong. I’m sure others will agree with me on this. Any high performance hull will act this way. When you hit that 70 mph spot hold it there until you are not gaining any speed at all. After a few seconds of say 70.2 mph bump it. It should start to rock out of control like you said. Eventually you will get a feel for this spot on the pad of the boat and beable to handle it here. Now you might climb up to 72mph. Once again let it stable out then try to bump the trim again. Once you get the rythem down it will be night and day. I’m pretty sure drewtick has some decent videos on correcting walk on his YouTube page. He has posted them here quite a bit.

[Jeff from Iowa]

Seriously??? Let's think about this..... Pushing a boat until it's out of control just to "try to learn" how to correct it makes about as much sense as sticking my finger in a light socket to learn how not to get shocked. If I have to drive the boat like that to get an extra 2-4mph, I'll deal with a slower boat and be safe and alive to come home to my wife and babies.

And if Phoenix designs their boats to have to be driven that way, then I made a wrong purchase. Performance on these near $100k boats shouldn't come with sacrificing safety.

Sounds like you got it figured out, dont try and get that exta 2-4 mph... easy fix.

[haus9393]

[haus9393]

Watch his hands when he puts them back on the wheel after pulling them off and the boat begins to walk. I’m guessing this is where you are losing control. All he does is turn the wheel from 12 o’clock to about 10 o’clock and back alittle bit and the boat flattens right out again.

[dps136]

What's would the 24fury do vs the 25 fury?

sounds like the 24 would get better performance?

[dps136]

Thanks for the video. I will do that at 70mph and can control it there, but when I try to bump it, it starts to dance, and I'm moving the steering wheel as before but now the chine just keeps getting worse and I have to pull back by dropping the trim to regain control. This is where I'm only at 5500-5600rpm.

[jayg4]

Took me a while to get the hang of driving one out of a chine from past boats I owned (Javelin especially). Having had a Ranger for the past couple of years I was spoiled in that you trim it up and it just rides there. I just got a new 721 month ago and like haus9393 mentioned these types of performance hulls are going to do it no matter the brand (Thats why they run mid 70's +.) Its funny when I figured out you didn't need to jerk the wheel around but move it through the 10 to 2 position and back in a fluid motion it got allot easier.