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Author Topic:   14.25 x 21 Stiletto on OX 66 225 hp Yamaha
peetmin posted 04-03-2004 11:02 AM ET (US)   Profile for peetmin   Send Email to peetmin  
I know this discussion has been touched on recently but I must press further. I currently have a 3 blade 14.25 x 19 pitch Stiletto on my 22' notch transom Revenge.I just repowered with a 1996 Yamaha OX66 225hp Saltwater series. I got 47 mph on the GPS at 5400 rmp (I fixed the tach yesterday logjam) yesterday with a full tank of gas and had more throttle to go. The boat jumps out of the hole and gets up to speed very quickly. My question is if I step to the next size Stiletto 14.25 x 21 will I be biting off more than the motor can chew? Has anyone traveled this path?
I just want to go 50 mph, Is that too much to ask?
Peter posted 04-03-2004 12:20 PM ET (US)     Profile for Peter  Send Email to Peter     
Yes, 50 MPH is too much to ask. I'm surprised that your getting 47 MPH at 5400 RPM. That's an excellent result and far more than I would have expected out of the Yamaha 225. I suspect you have no bottom paint.

A 21 inch Stilleto will put your WOT RPM too low. You want WOT engine speed on the high end of the WOT operating range, exactly where it is now.

Tom W Clark posted 04-03-2004 01:11 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

Sounds as if you've got things set up perfectly. 47 mph is very impressive, especially with your RADAR arch. If you go to a taller prop you will probably loose top speed, not gain it.

Did you measure your speed going both directions? What was the wind like yesterday? Where were you?

If you want a little more top speed, try burning off the fuel load and trim it ALL the way out.

LHG posted 04-03-2004 03:09 PM ET (US)     Profile for LHG    
I'm not so sure, guys. They say you should prop for max throttle under light load. He is saying he has more to go, with a full tank. It may handle a 21. Remember this boat does not have a Whaler Drive.

Pete, try her out with the nineteen under a half tank of gas and see how high it will rev. If it will exceed red line, you need more pitch.

I know Kingfish gets 50 out of his 22 with a 225 OMC & radar arch, and in looking at my Mercury prop charts for a 225 EFI, I show this engine pushing the Revenge 22 to 56 MPH (3600#-5500# load range, 19" pitch, 1.75 gear ratio). So I would think the Yamaha could get 50 out of her, even with radar arch.

peetmin posted 04-03-2004 03:15 PM ET (US)     Profile for peetmin  Send Email to peetmin     
Tom- It was pretty windy yesterday. I was running into the wind southbound in front of Gate's house along the East shore of Lake Washington. Problem was I was getting beat up by some guy in a Maxum bowrider. The nerve of that guy. I had it trimed as far out as I could before it starts to porpoise.
My first run was on Friday after I finished hooking everything up. I got 45mph (GPS) but my tach was kind of flakey and the lower unit was kicking up a lot of water into the transom. So I pulled the boat out and moved the motor up one more hole and dropped it back in the water. This time I got 47mph. I have corrected the erratic reading the tach was giving by removing the tach, pulling the rubber gromet/plug from the back and resetting it to the 12 setting and then reinstalling it. That seemed to correct it. Let me know when your ready to go.
Tom W Clark posted 04-03-2004 04:02 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     

You raise good points. We'll see.


Bring her over to Ballard tomorrow. We'll launch her at Shilshole, run her around with a couple GPSs on board and then retire to Hale's to discuss the results.

peetmin posted 04-03-2004 10:53 PM ET (US)     Profile for peetmin  Send Email to peetmin     
Alright I'll bury the hatchet on this one I just came in off the lake. This time I had the whole family on board. I got 47mph @ 5500 rpm but there is nothing left as far as throttle. Peter you are correct no bottom paint. Smooth as a baby's... well anyway very smooth. Tom, it's still hitched to the truck. I'll drag that hog to Ballard, Hell I bet it hits 70mph on the way. See you tomorrow. Pete
Peter posted 04-04-2004 07:47 AM ET (US)     Profile for Peter  Send Email to Peter     
Just as a point of reference, with bottom paint, the 225 Yamaha mounted so that anti-vent plate was substantially parallel with keel, and all the canvas up, the best I would get was about 43 MPH at 5300 RPM using a Yamaha 15 1/4 x 17 Saltwater Series stainless propeller. I've read before that these propellers are not designed for top speed, but rather, cruising efficiency. Seems to be true.

Larry, I highly doubt a factory Merc 225 EFI will push the Revenge to 56 MPH, even one with a slick bottom like Peetmin's. Performance estimator says the Revenge needs in excess of 350 HP to get there. A Merc 225 EFI doesn't produce 350 HP even on its best day.

peetmin posted 04-04-2004 12:11 PM ET (US)     Profile for peetmin  Send Email to peetmin     
I added a photo of the motor with the 5" vertical lift plate.
Peter posted 04-04-2004 04:19 PM ET (US)     Profile for Peter  Send Email to Peter     
Nice pictures of a nice boat. One thing-- I don't think your 225 is an Ox66. The cowling of Ox66 EFI motors say something to the effect "Ox66 Fuel Injection" on the sides and on the back. The top of the cowling on Ox66 motors say "V76" instead of "Vx76" Yamaha didn't offer the Ox66 EFI system for the 1996 model year. It was introduced in the 1997 model year.

This might partially explain the excellent performance. I've always suspected that the carbureted version of the 3.1 L V6 block is a little stronger because the motor isn't inhibited by the feedback control of the oxygen sensor. I had a friend with a 1996 225 Yamaha on a 20 foot Grady White and it moved it very, very well.

LHG posted 04-04-2004 06:34 PM ET (US)     Profile for LHG    
Peter, regarding the Merc 225 EFI's, I'm just the messenger here. I gave the mumbers directly from their prop charts. I have no immediate experience with the engine, except that I got "walked" in my 25 Outrage by a guy running a pair of them on a boat larger than mine.

But Louie Kokinis, who is running one of these on his widely published 22 Guardian, has said he can get 54 out of his (also with a 19" pitch prop). Louie has said that the BW/CPD people told him the engine is good for 240 horses. The 225 EFI's are faster than the 225 Optimax's.

Peter posted 04-04-2004 08:34 PM ET (US)     Profile for Peter  Send Email to Peter     
Larry, not trying to kill the messenger here, just trying to thwart what I think may be an unrealistic expectation for the Revenge. At 47 MPH, Peet's Yamaha 225 is easily producing 225 HP and perhaps a little more. Even if it were equipped with your favorite V6 Merc platform producing 240 HP (I've also read that elsewhere), an extra 15 HP won't take a boat like his from 47 to 56 MPH without the aid of an 7-8 MPH current.

Don't forget that the Revenge starts out 300 lbs heavier than the Outrage and all the extra weight is up front. Also, the helm is further forward. Thus, as compared to the Outrage, the center of gravity in the Revenge underway is further forward and is likely to cause more wetted surface under all trim conditions. More wetted surface means more drag and slower speeds.

I have found a good way to get an estimate of the appropriate pitch is to start with the performance predicting formula (provided by Clark) found on this site to estimate top speed for a given HP. Then, plug that number into the propeller calculator along with the motor's recommended WOT rpm, the gear ratio and a reasonable number for slip (6 to 10 percent) and let the calculator estimate the appropriate pitch. That process is remarkably good for figuring out where to start. However, testing is still required. As you know, not all propellers are created equal. One manufacturer's 19 inch propeller is not necessarily the same as the next manufacturer's. Also, different propeller styles of the same nominal pitch will yield different results.

Sal DiMercurio posted 04-04-2004 09:22 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
I tend to lean towards Peters thinking.
There's just to much boat there plus the radar arch to see 50 mph with a 225 hp.
There's no way that engine can twist a 21p prop to a reasonable rpm on that rig.
It's just to heavy in the bow to get her to break free & be able to hold her up & out of the water.
Yes, anything is possible, but in this case I don't think it's probable.
50 mph is scooting along pretty fast.
logjamslam posted 04-06-2004 02:25 PM ET (US)     Profile for logjamslam  Send Email to logjamslam     
Pete- you are one of the few guys that doesn't need a tach as your numbers confirm. Glad that things worked out as well as you thought they did.

I still haven't decided what I'm going to put on my 250 OX66 but I'm leaning toward the Stilleto 14.25 x 21 that you were considering. I have questions about a statement in another thread which stated that a laser II prop and a stilletto prop would not be recommended for a 250. I have seen Sal recommend them for several 225 applications in the past and your numbers are certainly impressive; I can't believe there would be that much difference between your 225 and my 250.

kingfish posted 04-06-2004 03:09 PM ET (US)     Profile for kingfish  Send Email to kingfish     

I've been out of town for a couple of weeks (Apalachicola, FL) so am just catching up with the forum, and wanted to make a couple of comments.

First, *really* nice website! If I've seen it before, the fact got lost in my failing retrieval system...

Secondly, as per LHG's comments and just confirmed during the past two weeks, I still get 50 mph GPS after I added my arch in ideal conditions with a 1992 225 Evinrude. I can never remember the pitch of the prop, but it is a cupped and raked OMC 17" stainless; the ventilation plate is about 1-1/2" above the keel line, and the motor is trimmed up until it starts to lose speed, @ 5600 to 5700 RPM.

Your 47 mph @5500 RPM with the additional weight and wind face that a Revenge carries compared to an Outrage ain't too shabby. My $0.02 worth would suggest that you might have a very small amount of tweaking left but not much; I'd be surprised (but interested to hear) if going to a 21" prop would be of help. I would try to raise your motor a little if your jackplate will allow it. It really sounds like you're dialled in pretty well. That OX66 225 is a really nice motor.


rtk posted 04-06-2004 07:16 PM ET (US)     Profile for rtk  Send Email to rtk     

Is this the thread you were talking about?

I just repowered my 1997 21 Outrage with a 2003 250hp EFI. The LaserII 19 pitch is what came with my boat on the 1997 225 carbed Mercury. Based on the description of the prop on the Mercury site and discussions with a few people, it did not seem like a match for the boat. The boat just went in last Friday and I have not had a chance to run her due to the lovely weather we are having in New Jersey. I'm starting out with a 4 blade the dealer had around. I was out today for a little while and I'm not overly impressed with the 4 blade- max rpms at 5500 was ok but it was cavitating alot even with minimal trim. I still have the LaserII which I am also going to try, and I would also like to take a Mirage out for a spin. I'll certainly let all know how all the propellers performed and I am open to suggestions still. Great info on this thread. Peetmin you are getting great numbers out of that set up. With the 19 pitch LaserII with my Mercury 225 carb I was only getting about 5300 RPM max and my max speed was 46mph according to my GPS. Hole shot wasn't great either. That is why I wasn't happy with the LaserII and looking for an alternative.


peetmin posted 04-06-2004 08:17 PM ET (US)     Profile for peetmin  Send Email to peetmin     
John, Great to hear from you. Iím glad that all is well with you and yours. Thank you for the complements on the web site, it has been fun. If Iím reading this right (and even if Iím not) it sounds like I need to go out and try to raise the motor to the top hole. As it stands my anticavitation plate is level with the bottom on the keel. An inch above may lead to better results. I donít think it is going to stop drawing water.
Alright, Iím going outside to raise it up. As for the 21Ē prop, I think it would be too much. Iíll let you know what happens. Pete
peetmin posted 04-06-2004 10:40 PM ET (US)     Profile for peetmin  Send Email to peetmin
kingfish posted 04-07-2004 12:43 PM ET (US)     Profile for kingfish  Send Email to kingfish     
Pete (et al)-

I don't think I could have screwed up the prop data in my earlier post much worse - my apologies.

What I have is an OMC raked and cupped stainless prop of 19" (not 17") *pitch* (not diameter); it appears the diameter is 14.25 (can't tell about that for dead sure; it is 14 and some fraction or decimal, but has been worn away and I can't read it).

Bigshot posted 04-07-2004 01:35 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
A couple things....that Yammie is not a OX66, just a salt water series.

My 225 Johnson with a SST 14.5x19 prop at 58-5900rpms I get about 50 on the nose on a 20' Hydra-sports with a t-top. Boat weighs 2200 so close in weight to the 22 outrage but deeper V(24 degree). I am not sure what the 225 yammie redlines at but if 5500 I would try a 21" if you run light loads. Honestly I think it will be a waste of time and even though it might hit 50, it won't perform as well with heavier loads and speed will suffer.

kingfish posted 04-07-2004 01:46 PM ET (US)     Profile for kingfish  Send Email to kingfish     

Incidently, The OX66 225 we have is on a Parker we keep in the North Channel of Lake Huron (Canadian waters). It came from the Parker factory installed correctly as I have come to understand it (pretty unusual industry-wide). It is mounted as the 225 OMC is mounted on my Outrage, with the ventilation plate about 1-1/2" above the keel line. Works fine, good cooling water pick-up, etc. Again, it's a great motor, though surprisingly loud at times.

Another condition just occurred to me relative to the mounting height of your motor, and that is that if you have gained any set-back with your jack plate, you can err towards a higher setting with your motor height, if settings allow. More like 2" perhaps rather than 1-1/2".

peetmin posted 04-07-2004 06:42 PM ET (US)     Profile for peetmin  Send Email to peetmin     
Biggie- In regard to the OX66, you are correct. Peter pointed that out earlier in the thread. That was an assumption made on my part and my mistake. The motor was not sold to me as such. The 19 Stiletto is going to stay. I may have it worked on to try to lower my 30 mph cruising rpm. I raised the motor to the top hole last evening and snapped a shot of 48mph. The boat actually hit 49mph but I began to hit my wake from my first trip in the opposite direction and had to slow down before I could get a shot of it. I am done with the high forties for a while. I think itís hard on the engine. Pete
Peter posted 04-07-2004 07:05 PM ET (US)     Profile for Peter  Send Email to Peter     
49 MPH! That's amazing. Sure you don't have a 250 hiding under that 225 cowl?

With your motor jacked up high, I think your rough water handling is going to suffer some.

Sal DiMercurio posted 04-07-2004 08:36 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Kingfish, somethings not right here.
A 17p stock OMC prop spinning at 5600 - 5700 rpms wont turn 50 mph on that heavy of a boat, even if the prop is cupped & raked.
I don't know if there's current on the great lakes but either your gps is wrong or you were going with the wind & current.
I don't recommend a Stiletto prop for boats over 24' - 25', unless it's a racing hull or a very flat bottom hull.
Sal DiMercurio posted 04-07-2004 08:52 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
The prop calculator says you are running at -3.6 slip,....... no such thing as a stock oem prop running at minus -3.6 slip.
I've seen many gps units read either very happy, or very sad, like 20 mph off in either direction.
Don't ask me why because I really don't know why.
For instance, last year someone on this site said he was running a 16 ft whaler with a new 90 hp Evinrude, his gps said he was doing 32 mph.
He happened to live only a few miles from me, & we both took our boats out & I clocked him at just under 50 mph [ 2 gps's, speedo, & sonar, only 1.5 mph difference between all 3 ] while his gps said 32 mph.
Tom W Clark posted 04-07-2004 09:40 PM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
No Sal, your calculations are wrong. John has a 19" pitch stainless steel prop, not a 17" prop.


Nice job with your boat. 49 mph is nothing to sneeze at!

kingfish posted 04-07-2004 09:59 PM ET (US)     Profile for kingfish  Send Email to kingfish     
Sal and Tom-

I caused the confusion with my first post, in which I erroneously stated my prop was a "17"; it is a 14.25 (I think) x 19. Sorry.


If it's not an OX66, I can't claim to any first hand experience, but I certainly bow to Peter's observations, and concur with Tom's comment: nice job!


Sal DiMercurio posted 04-07-2004 10:36 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Yep, a 19p will make it, but not a 17p.
logjamslam posted 04-08-2004 06:27 AM ET (US)     Profile for logjamslam  Send Email to logjamslam     
Sal- no Stilleto props for non racing hull over 24'or 25'.
How about 22' with WD and 250 OX66 ? The whalerdrive puts me at 24'. The outfit that you recommend still has a great price on stilleto props and I'd like to use one if it would work for me.


Sal DiMercurio posted 04-08-2004 10:41 AM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Greg, a 22' is fine even with W/D.
The reason they aren't the best is, the largest diameter they make is 14.25 which isn't big enough to hold the bigger boat up.
LHG posted 04-08-2004 06:32 PM ET (US)     Profile for LHG    
I have seen Kingfish's rig, and his prop is a high quality OMC RAKER performance series. This is similar to the Mercury Laser II series which I use, and this particular family of prop designs (which include Stiletto and Rapture) are for speed with lighter loads, elevated 1 1/2" running heights. For lower HP to weight ratios, these props are not recommended.

For all you propeller heads, (I include myself in this), I recommend you visit and study their highly informed comments on prop design, # of blades and configurations (rake), mounting heights, diameters, and APPICATIONS for each. Also, on-line order one of their prop catalogs, which also has a lot of useful information.

Getting past the brand loyalty stuff, there is a lot of information to be learned as to what might be the best for your particular rig. Then, if you want some other brand, fine, find one with similar properties and you should be fine. Remember, not all props are created equal, in spite of how they look.

Concerning some of the questions in this thread, I think Peetmin should not be running a Merc Laser II/Stiletto style prop, but instead a Mercury Mirage Plus style (larger diameter) prop, or hot new 4-bladed Revolution 4 prop (I don't think any other brand has one of these out yet).

I think rtk, with a heavier 21 Outrage, although getting pretty good speed out of that Merc 250, should also be running either the fast Mirage Plus or Rev 4 prop. Mercury does not recommend Laser II's on the 3.0+ liter engines, saying these engines on heavier boats need the increased blade area of the Mirage Plus to carry the hull, particularly in single engine configuration.

The Whaler 320 Outrage with twin Merc 250 Verados I experienced at the Miami show, was running Revolution 4 props, as does the boat when rigged with twin 250 Optimax.
Supposedly they are whole new family of offshore 4 bladed design, with no speed loss against the 3 bladed Mirage.

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