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I am running a 2004 Mercury 25" Saltwater series 200hp on this boat no jackplate, she is propped with a merc vengeance 21p 3 blade SS prop. She turns 6000 rpms at WOT with 43mph , I am thinking of going to a Mirage Plus 21p to get some more stern lift and low end plaining anyone have simular set up i know i am way under propped with the numbers. thanks

thanks CT.

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You should be running a 20” shaft motor on that hull. Not 25. Your going to need a jackplate to raise the motor.

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I just realized I did a typo , I do have a 20", confirmed

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And what does the manual say the WOT RPM's should be?

If it is 6,000, then your prop is just right

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5400-5600rpm is manual, also my stern rides real low and have to run trimmed all the way down , top end is 43mph.
I was thinking of switching to Mirage plus prop to get some stern lift and better handling at lower speeds.

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pic

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She floats great. That motor should be good for 50mph on that hull. Tom Clark is the man when it comes to dialing these in.

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It sounds like you have an engine problem, or you may have a prop hub slippage problem. Check your prop first for a "spun hub" as they call it. That boat should run 46 MPH with a 2.0 Liter Mercury 150 (as mine did), and you have a 2.5 liter 200, a LOT more power.

Max RPM is 5600 as noted, and the engine should be mounted in the middle (3rd) set of holes. You should be able to get 54 MPH out of that rig running 21" pitch. I have been in a 21 Outrage with a Merc 175 EFI and it indeed did run 54, using a 21" pitch Laser II prop. i agree that a 21" Enertia would be the prop of choice for your rig, but I would get engine running properly first before spending the $500.

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Yes you are right there is a few others with the 175hp's getting 45-50mph I am right at 44mph but im spinning 6000-6100 rpms with a 21p vengeance. The motor has been checked and carbs cleaned by a real good mercury guy here in houston, its tip top. I need to get propped better, I ll check the mounting as well.

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Your engine has has a 1.87 gear ratio, and with that and a 21" prop, at 6000 RPM you should be running at least 57 MPH. So you are getting major slippage at the propeller. Using the RPM you are showing, your boat is running like it has a 16" pitch prop.

I have a pair of Mercury 200's on my Outrage 25, and several years ago, at a Whaler event, a Mercury factory racing rep set my boat up with a pair of 19" Revolution 4 props, and managed to get it up to 6300 RPM and 62 MPH. I only mention this to show that your rig, at 6100 RPM and 21" pitch, should easily be going 57 mph

Prop hub slippage is definitely your problem, unless splines on your driveshaft are stripped at the crankshaft, something you don't even want to think about!

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When I first got the boat it came with a Trophy plus 21p, I took it for a spin but noticed when I gave gas the engine wanted to lag behind and then after slowly increasing the throttle she would come up this would be perfect for the slippage theory right ? When I switched to the Mercury Vengeance 21p prop with a flo torque II hub kit I noticed the engine didn't do that, when you gave RPM's she climbed right up as supposed to but still 6000 rpms, now given that the hub kit is old and has noticeable wear on the edges I will just order a brand new one and see if that helps maybe I still am getting some slippage at higher RPM's. I do agree with you guys the HUB seems to be an issue, thanks for all the help, Ill post updates as i get them.

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You would not need a new hub kit - just the replaceable black drive sleeve. Once you have the prop off, a deep socket that fits the prop nut is perfect for driving the old sleeve out of the prop. Hopefully you will find a deformed drive sleeve.

If this does not solve your problem, drive shaft splines could be the problem. Several years ago I had the same problem you have described, and the splines in the bottom of the crankshaft (where the drive shaft fits in) were badly worn, causing the slippage at higher RPM. The fix is an engine rebuild and new crankshaft!

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Capt, you didn't mention how you are measuring speed and RPMs. Accurate?

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You should have no issue running 50 mph with that engine. I'm running 50 with a 175 Suzuki with a 3x16x20 prop.

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measuring speed by my plotter and cell phone both are accurate and rpm gauge is brand new and accurate. I will install new hub and run it next week and follow up with y'all.

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installed new hub and same story no change, I will play with props and see what I can acheive 44mph 6000 rpms today, 21p trophy plus.

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Since you have now eliminated prop hub slippage, the slippage is coming from somewhere else, and there are not many places left!. As I said in my March 3 post, I would again guess that you have a crankshaft/drive shaft spline problem. If you do, eventually it will let go completely. You may be looking at a new crankshaft as a fix. When a failure happens where the drive shaft enters the crank, the worn splines in the crank are usually the problem. There are two ways that this joint fails. One is jamming the gears from forward into reverse at higher than normal RPM (idle set too high), the other is "wave jumping", where the prop spins loose coming over a wave, then bites hard on re-entry. This will do it quickly.

If it's not that, I am stumped completely.

Your numbers indicate you should actually be running a 23" prop, to keep the RPM's down to 5600. At 5600 RPM, running your 1.87 gear ratio in the lower unit, and a 23" prop, you should be getting close to 58 MPH. So, major slippage is occurring somewhere.

Run the engine up through the rpms, and see where the slippage starts to happen. With your setup RPM's should match speed closely. That is, 3000 RPM should be close to 30 MPH, 4000 RPM should be 40 MPH, etc.

Also, do you know the history of the engine? If you bought it new, and know how you handled it over it's life, that could invalidate my theory. But if used, and history is unknown, that would add credibility to my guess.

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Yes i know the orignal owner he bought engine new in 2004 he said it had less than 100 hrs when we pulled out of storage last yr. i even ran a power tech 4 blade ofs 17p and same thing 44 mph 6000rpms. So something is wrong im not sure if i have a water logged hull ? Or like u said slipage issue with shaft. The bow rides high i have to keep trim down even put a hydrafoil on drilless to see if helps but same just a little better hole shot still same numbers. Lol

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Based on your one pic above she floats great. Do you have any photos of her out of the water showing the motor mounted?

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This has got to be the worst picture upload forum in history can t seem to get a low quality image to load idk why i give up, okay so basically there is 4 holes vertically I have a bolt threw the top hole.

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I don't have a classic Outrage 21 but you were told she floats good and I agree looking at the picture you posted, therefore I doubt you have a waterlogged hull. Also she must be really, really waterlogged to drop that much in speed and she floats fine.
Moving engine up or down on a transom doesn't make her float different .
Therefore if it isn't mechanical you must adjust the motor height mounting.

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Photo:

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Photo 2

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thanks Phil T , your the man. these are pictures of my boat, yea I also agree she floats just fine. gunna borrow someones bigger prop and see what happens if not I am narrowing it down to mounting which doesn't look bad to me if its off its slightly off. Ive had 3 other boats with jack plates and they all ran good weather 6 or 10 inches up or down so I am leaning on this slip issue with the gears now, idk keep y'all posted thanks for the help

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Seems to only do this with certain props so , could be hub issues still moving on to another issue i seem to be getting water in the forward deck hatch ? not sure how water can get in there im worried that its coming up from inside hull ? Is this a common problem or known? thanks again

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Well sorry to get back to this so late, but a few test runs later I busted out the Lower Unit I was coming up on speed and .....done deal lots of busted parts in LU, so my mechanic had a good used one for $600 and got it all back together for me will be starting back again with props but if i had to guess maybe I was slipping gears and had lower unit issue. all the hubs were checked and in good shape when i marked them they showed no slipping, when i checked gear oil it was mostly water and the seal was shot so I am leaning Lower unit was the issue for sure. Ha LOL. Will start sea trials again in Jan 2019.

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CaptTrojan sorry to hear about your lower unit, but good to hear too as that probably was your problem.
Keep us abreast of your findings once back running in the water.

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well got some more issues, for now i am looking into fuel tank replacement, does anyone know where i can get a fuel tank ready to go to install myself for this boat, I've seen that u can call Florida marine with dimensions but is there a Moeller model # for one on this boat already that i can order online?

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There is not a off the shelf plastic tank available. Either custom fabricator uses your existing as a template or FMT.

Alternative is to run a on-deck portable temporarily.

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may just run an moller above deck one for now, thanks again.

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I am in the middle of installing a above deck Moeller fuel tank, manual jack-plate. Also GPS and electrical work. Boat was running but fuel pump is bad, so I will also mix my own gas and get rid of the oil pump before it eventually goes out as well and causes issues. I will update soon hopefully.

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The Mercury oil injection system on a 2.5 liter 200 is driven by a gear on the crankshaft. Unless it is ruined by excess RPM (running the engine over 6300 RPM continuously), removing the oil system on an engine that size is big mistake. Using 50 to 1 will give you a lot of smoke and generally be more expensive, plug fouling, with added hassle of mixing a lot of oil. The oil system provides a 100 to 1 mix at idle. The only time you're ever using 50 to 1 is at WOT.

I have run, and am still running, more than a few 2.5 V-6 Merc 200's, and have NEVER had an issue with the oil injection gear on the crankshaft. It's the hot rod/performance/racing guys that tend to strip that gear with prop spin-out wave jumping and high RPM running. Which leads to another general warning - never buy a used Merc V-6 where the oil injection has already been removed - it's a clue the engine has been run too hard or had some serious overheat issues.

I would have a good Mercury mechanic check out and calibrate the oil system, and if it mixing properly, leave it alone. And don't run the engine over it's redline rating of 5600.

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Okay good to know, at this time the oil is not mixing at all. I put a 50:1 in the tank as a safe guard and looks like the oil level has not come down at all after 3 hrs run time. since I put the pre mix in tank and the engine is running great with some smoke. no bogging or dieing on slowdown. either way the motor is mounted two low I am dragging the ass and the cavitation plate is under water while running. So i am installing a manual Jack plate next. ( SO FInnegan could I get away with a 75:1 if I am not really opening it up for a few minutes back to the dock?)

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I would not run 75:1 even with synthetic oil. Was the lower unit the problem? What is she running now?

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Still runs 42mph , I am thinking the engine is 4+ inches to low. when I put the yard stick under hull even the cavitation plate is 2+ inches under (lower) than stick. so raising the engine should definatley help. there is alot of spray and the boat porpusies if you try to raise the trim slightly from all the way down.

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CT -
This hull takes a 20" shaft and you are running a 25" as noted in post #2.

You need to raise the engine 5" at least and that is only possible with a riser or bracket. To keep weight down, I suggest these. Uses existing holes in the transom.

This gives you 5 1/2 inches of rise.

https://www.wholesalemarine.com/t-h-m...ack-plate/

You will want the anti-cavitation plate at least 1 - 1 1/2 inches above the bottom of the boat.

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Snap....25" on a banana will definitely shave 5-10mph. get a manual jackplate and jack it as high as you can. 5-6" is the range on them usually. They are not too expensive, should be under $200.

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Thats exactly what I am doing its at mech shop now hes putting manual Jack plate, and a few other things will update again in couple weeks, thanks for the help!

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Well I got her running and wouldn't you know long story short blew 2 cylinders, so engine is for sale for parts hopefully I can get something else and get it going Ill be back with an update, LOL.