1996 tf 495 with an 2009 mercury 250 pro xs. Prop is 22p mercury tempest plus.

WOT, I run 60mph @ 5900 rpms.

My engine manual says full throttle range is 5500-6000 with rev limiter @ 6250 rpm.

Seems it's right in the guide lines, was trying to determine if I should change props for more top end. 

That's full tank of gas, me and all my gear. 

Thanks

 For what you have, it sounds like you are dead on.  Going to a higher pitch thinking it will give you more speed is not the way these things work.  A higher pitch prop will load the motor down more and could actually cost you speed.

Are you running a jack plate, if so, what size (how much setback)?  What's your prop height set at?

I've never had any dealings with a Charger boat, but have always heard they ride a little heavy.

Now, I'm going to suggest you do some research on line about your boat and what speeds they typically run with 225 - 250hp. 

The reason for the questions and suggestion is that seems very slow for that size motor.  I have a 20ft Javelin that weighs about the same as a 20ft Charger and a 250 will push it in the upper 70s.

Understand, with the info you have given, a 22" pitch prop is what you should have, but!! that's sounds like it's compensating for a very bad setup or a motor that's down on power.  Might consider doing a compression or leak down test on you motor and look at the plugs to make sure that are all burning the same color after you have made several minutes of WOT and not let it idle for any time.

Also, I go back to fist comment in that I have never messed with a Charger and know nothing about them, and what you have may be perfectly normal for that boat, but it's a lead sled if it is.

 

Something is wrong with the boat/engine set up using 250 hp with 22" pitch prop. The speed seems about right for 22" pitch prop at 5900 rpm's, however a 250 hp OB should be running 25" pitch 3 blade at 5900 rpm's on a 20' bass boat. If you said 150 hp OB then it sounds about right!

As suggested check the set up, it sounds like the hull is pushing water instead of up on the pad.

Tom

@Way2slow @WRB

 

Appreciate the replies guys. Agreed, I felt for this motor I should be doing better, this is why im starting to research it. 

 

I took measurements, might not be exact but I believe they're close. 

 

Jack plate- 10"

Prop diameter- 14.5"

Prop height- 5 1/2"

 

This motor was swapped onto the boat, and the previous owner wasn't a big fisherman, just a weekend warrior, wherever he could make it. So to say if this prop was really ever fit for the boat is hard to say. 

 

The motor, too me at least, seems to run strong and doesn't skip a beat. I guess I would need to have the compression checked to really know if it has a power loss.

 

I have actually been talking to other charger guys, and they're basically saying exactly the same as you. Everyone is suggesting a 24-25 pitch prop is needed for this combo. A guy who has fit several brand new from factory says that a 26 and even 27 is not out of question. With those he has seen 75-77mph. Everyone else thinks ohhhhh should be seeing low to mid 70's.

 

So im hoping someone in one of my clubs have a prop I can throw on and test it to see what I can get and maybe help narrow in on what prop I need. 

 

Way 2slow, you say that a higher pitch could actually have reverse effects? How is that possible? Not doubting you, just in trying to learn all this and understand.

 

Ideally wouldn't the lowest of the recommended rpm range be best (5500), most fuel efficient, and easier on the motor? So with the 22p running on the high end, is it not obvious that going to a higher pitch it would make it run easier and faster while also being more efficient? 

 

Sorry for the long post, but appreciate your thoughts. 

Two stroke motors are rather unique. They don't like to be loaded.  I'm not even going to try getting into the dynamics.  Not sure how much you are into fast cars, but look at NASCAR.  They are not decreasing gear ratio much to make them run faster, they are increasing RPM.  They usually only.

You seemed to be set on thinking a higher pitch prop will be faster so go for it.  The prop you are running may have a rolled blade that's not obvious just looking at it so trying a different prop would be a good thing do.  I would strongly suggest you find someone that has a known good prop that you could try before forking out the bucks for a new one, and I hope you wouldn't even think about running an aluminum one on that motor.

 

One other thing I might suggest, take everything you can out of the boat and take it and get it weighed.  Then subtract the motor, TM and other stuff left in it and see if you are close the factory dry hull weight.  The reason for this is to insure you don't have wet floatation foam.  You can get the trailers weight by launching the boat and then take the trailer and weigh it.

 

 

With the centerline of the prop trimmed parallel to the plane surface pad it should measure 3 1/2" not 5 1/2. 2" too deep! Try a loaner 25" prop from a dealer. 

Tom

1 hour ago, WRB said:

With the centerline of the prop trimmed parallel to the plane surface pad it should measure 3 1/2" not 5 1/2. 2" too deep! Try a loaner 25" prop from a dealer. 

Tom

Is the 3 1/2" a standard for all boats? 

41 minutes ago, FordsnFishin said:

Is the 3 1/2" a standard for all boats? 

It's nominal prop shaft depth for bass boats with plane pads. 2" too deep also explains your sluggish performance.

Tom

My Javelin runs best with the prop at 5 to 5 1/2 inches low.  I gets the bow up and holds it.  If I go any higher it keeps dropping the bow at WOT.  Back off the throttle just a touch and the bow hops back up, go back WOT and it drops.  Running deeper gives it more leverage and it holds fine.  This is also with custom tuned props to give it more bow and stern lift.

Drier the hull runs and more air to lift it the deeper the prop can run, i.e.; tunnel hulls and hydroplanes. The OP 20' bass boat running 60 mph with 22" pitch on 250 hp the hull is running too wet IMO.

Tom

So last night I adjusted the prop to pad height back to 3 1/2 from 5 3/4.

 

Took on water today. Oddly enough this did not change the rpms it ran at, however I lost 5mph in the process.

That supports what Way2slow, Kieth, was saying about bow lift. Losing 5 mph at 5,900 rpm's indicates to me your hull is pushing way to much water and not up on the pad. When you trim the engine up does start to throw a  3'-5' rooster tail? It's to comprehend 250 hp with 22 pitch 3 blade SST prop on any bass boat.

 Have you weighed your boat to make sure it isn't heavy with water in the floatation foam? Checked the plane surface to be sure it's flat and not cupped?

Tom

@WRB no I have not unfortunately weighed the boat. Will be a process with the lake being 40 minutes one way from the nearest scale that I know of.

 

To be honest im not sure about the rooster tail as I haven't paid attention to that. I just dropped the height an inch just curious to see what it will do. 

 

You mention water in the flotation foam. Say there is, what would one do about that? Is there  a way to dry it out and keep it dry. Seems it would be impossible. 

 

The bottom pad does not appear to be cupped. 

 

Im about to buy a compression gauge so I can see what I'm getting on all 6 cylinders. If I recall should be around 120 lbs each? With a +/- 5%?

I am curiuos about how you trim up the engine while running. The normal procedure is trim the engine down to start the boat get up on plane, then trim up the engine until the bow lifts to reach maximum speed without over trimming creating higher rpm's without increasing speed. Over trimming usually creates a higher rooster tail hence the question.

Water in the floatation foam is expensive to remove and repair the leaks. The boat usually requires taking the cap off (top of the boat hull) and drying out the foam and finding where the water got in. Some hulls used wood glassed over transums that dry rot and leak.

Tom

I use a blinker trim. 

 

Trimmed nearly all the way down, accelerate until what I consider the boat being on pad, (nose drops back down), than I accelerate further while trimming up until I reach my desired speed.

 

From driving the boat I've found what I've thought to be the correct trim for certain speeds. Which is typically that sweet spot where it's easy to steer, and maintains my speed easily. 

 

I don't feel that I'm over trimming, but maybe I am. Just going from my the feel of the boat and my own personal data. 

 

One factor I should mention, last year I redid the boat and moved my 2 31 series batteries to the very front, which were sitting clear in the back originally. With the boat set up this way,  I saw 64 mph. If I had a long stretch of water I could hit 66mph. 

 

The process of drying the styrofoam sounds like a nightmare. I think I'd be better off sinking the boat and collecting insurance at that point. Hahaha 

Put the 150 lbs of batteries back in the rear storage compartment.

Go borrow a 24"-25" pitch prop and you should be about 70 mph.

Tom

By the late 90's I would think most manufactures had changed over to closed cell foam, but weighing the boat is a quick way to check it.  Some boats run a drain in the floor right at the seats.  If you have that, you may be able to open it and do a core sample, if it doesn't have a piece of PVC drain pipe in it.

When they first started using flotation foam, they used open cell foam because it had a higher flotation value, but if water was able to get to it, it would absorb the water and hold it.  I had a 89 Stratos 285 PRO that was so saturated, the boat weighed 290 pounds less once I got it out and replaced it with closed cell foam.  Replacing the foam is not something the for the not knowing.  The cap has to come off, all the old foam dug out and new foam poured in.  Pouring too much in can actually bust the hull and rip the floor apart because it swells up to 10 to 1 within several seconds and you only have about eight seconds working time for the time it's mixed to it starts to expand.

 

If you have the batteries in front, get them back in the back.  That much bow weight will kill the crap out of bow lift, causing serious wetting of the hull, which as mentioned, kills all chances of making speed.

Did some playing around today. 

 

Got the batteries moved back to the back hatch and all rewired.

 

Located a 25p fury prop from a guy and got it installed. 

 

Right off the bat I noticed it took longer to get on plane, no big deal.  However,  I was only seeing 56 mph, @ 5000 rpm WOT. 

 

Fished for a bit,  put on trailer, and lowered pad height from 4.5 to 5.5 inches, which is what it originally was. 

This allowed me to hit 58, @ 5200rpm wot.

 

So perhaps this thing was already propped out and my 22p is going to be the best route. Im about to swap the props back around. Than when I go back out I'll make sure I'm still in my old range. Maybe play with prop height more to make sure it's dialed in. 

 

@WRB @Way2slow, as always guys, you are very helpful and I appreciate all the help and knowledge. 

 

Btw, I was able to get on some fish today,  and i did my good deed for the day,  had to tow a guy clear across the lake.  His 2 week old mercury quit on him. 

I still say that old saying, "There's a fox in the hen house somewhere" 

Like I said, I've never had any dealings with your hull so it could be the lead sled it is and just won't fly the hull, BUT, my 99 Javelin Renegade 20 DC is the same size and about the same weight.  It spins and 26" Raker @ 5,800 rpm with a stock 225 Ficht in the low to mid 70's.  250HP will push it in the upper 70's and my 300+hp hotrod motors will push it in the lower 80's with 450 pounds of body in it, a big, heavy TM on the bow, three 65 pound batteries, at least 20 gallons of gas and a ton of gear.  When mine is up an flying, you just get a little vibration in the boat where it's just skipping along on top of a lite chop.  There's probably less than a foot of the pad touching the water.

Too bad you're not closer to middle GA.  I would luv to be able to get my hands on that boat and see if it's really that slow.  Checking the motor, hull for a hook, possible wet foam,  and general setup. 

Even an old Stratos 201 from the era, which is not a super fast boat will run in the mid 70 upper 70's with a 250.  Several years ago, I built a 3.0 Johnson for a friends 93 201 that dino'd 297 hp at 6,200 rpm and it would run 78 with me and him and gear, both of us were over 200 pounds each. It would actually run 81 in peak tune, but a fattened the carbs up one jet size to make sure he didn't lean it out on a damp cool morning and that slowed it down to 78.6.

Are you sure the tach is correct?  Do you have any throttle left when the 22p is on it and you are in the recommended RPM range?

 

The hiccup in this theory is you should have a lot of throttle left with the 22 on it if the tach is off (showing higher RPMs than it really is turning).  You should be able to bury it in the rev limiter with a 22p on a charger with a 250 pro XS if all else is correct.

@Way2slow @imbatman I do agree, something is not right. 

 

Id slow to go over the boat with you way2. Im eager to learn more about the mechanics of boats and always enjoy self diagnosis. Knowledge is something nobody can take from you. 

 

Im bat, I do not know for a fact that the tach is accurate. However when ther motor was installed it also got a mercury smart gauge which id assume is fairly close. The motor has a built in rev limiter @6250rpm so it doesn't appear to be going over. 

 

2 questions. Judging from my prop and the guys I used. Mine has much more soot inside the prop from the exhaust. Maybe 1/32" thick and hard to remove. While his was essentially clean. 

 

Other question. How much affect does the performance exhaust ports on the prop make? Mine has 3 locations, 2 of which are completely removed. When I bought the boat I remember it struggling to get on pad at first and I took them out finding it made a big difference on hole shot, but I have no idea what it did to my top end. 

In terms of weighing your boat + trailer, and then just the trailer, in your part of the country, any small town grain elevator will have a drive on scale.  Hopefully you can find one closer than 40 minutes from the water.  I grew up in Iowa.

If it is a Smart Craft Gauge it is most likely correct as they tie directly into the ECM.  They would be accurate or not work most likely.

 

You did the correct thing with the vent holes in the prop,  they just allow a little more air/exhaust around the prop at low RPM to help it spin up faster.  They have basically zero effect at speed as that little bit of air is swept away at speed, not around the prop blades like when coming out of the hole.

 

The soot is a little odd but could just be crap fuel used previously or running a little rich.  As long as you are not getting any warning lights you kind of have to assume all is okay.  If you had any kind of fuel delivery, over heat, low compression issue the SmartCraft should throw a warning.

 

Here is a prop slip calculator.  You can plug in your #'s and get the slip you have  You should be in the 10-12% range and you are 15%.  Prop slip is how far the prop should push you in one revolution vs how far it does.  The more slip you see the more drag you have taking away from the forward travel.  That goes along with those that say you are pushing to much water.

 

https://www.mercuryracing.com/prop-slip-calculator/

 

Still you should be turning a 25 or 26 @ 70+ at about 3-5% less slip that you have with a 22 @ 5900rpm.

 

Any chance you stand behind the boat and take a pic with the motor down?  Take it from down low.  It will tell us anything about the actual prop to pad measurements but maybe there is a miscommunication about something.

 

 

 

 

I think you just told me what the problem is, and it's not the boat, it's the motor.  Sounds like it's running ungodly rich. 

Next time you take it out, take something with you so you can remove the spark plugs.  Do it in the driveway first just to make sure you have everything you will need.  While you are doing the driveway trial run, pull the air silencer off so you can see the butterflies in the throttle body.  Press the hot foot full throttle and make sure the butterfly's are going fully open and not beyond full open.as

Now, when you take it to the lake, make a WOT run for about five minutes.  Do this so you will be back close to the ramp at the end.  While still holding it at WOT, turn the ignition off, do not let it idle.  Use the TM to get back to the ramp and on the trailer if need be.  Now, remove all six plugs and see what color they are.  In that motor, they should be almost snow white. If a little tan, that's not too bad, but if any are dark or even black, that cylinder has a major problem. 

So just removed the plugs and did a compression test. Which now as I type this I realized I messed up and did not run the engine prior and warm it up. 

 

From what data I did recieve, it did not appear to be off by but 1 lb on any cylinder. 

Working on removing air silencer now to look at throttle plate. I stuck my finger in to see its position, and feels like it's covered in suit.

 

It's only letting me do so many photos right now, I'll post ther other plugs later