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Author Topic:   225 Ocean Runner performance
Smallfrye posted 07-07-2004 08:49 AM ET (US)   Profile for Smallfrye   Send Email to Smallfrye  
I just added a 1998, 225 Ocean Runner to my 20' Guardian. Set up with a 10" set back plate, 18" pitch S/S prop and the motor lifted so the cavitation plate is at the water line when on plane, Perfomance is not what I expected.
I thought the 18" prop would spin a little high but here's what I found:
2700rpm: on plane, 18mph
3500rpm: 20- 22mph
4000rpm: 23- 24mph
4500rpm: 27- 29mph

I'm not sure of the WOT limit for this engine and as the maiden voyage, I did not want to push the rig until the bugs are worked out.
Would those of you who have similar rigs provide your performance comparisons or comment on this situation ?
All opinions are welcome.
Thanks, Jim

Peter posted 07-07-2004 09:30 AM ET (US)     Profile for Peter  Send Email to Peter     
WOT range for that engine is 5000 to 6000 RPM and should be setup ideally to run above 5500 and as close to 6000 as possible as you are typically loaded. You are experiencing quite a bit of slip which suggests to me that the propeller is either not running deep enough or has a spun hub. It's most likely that you need to optimize the position of the motor. What type/brand/diameter propeller?
Smallfrye posted 07-07-2004 11:14 AM ET (US)     Profile for Smallfrye  Send Email to Smallfrye     
Thanks Peter, the prop is a standard OMC 14.5X18. This came with the motor and I thought it may be a bit small. Merc's prop selector recommends 19-23" based on objective. I though or moving up to a 21" prop and leaving the engine height as is. The height seems a little high over the transom line, but the prop seems to be running deep enough, breaking the water surface about 1" above the cavitation plate.
The set back plate causes a slight wake over the prop, this may contain to much aeroation, causing the slippage ????
Any thoughts ?
Bigshot posted 07-07-2004 11:53 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Something is SERIOUSLY wrong. First off check to see you are getting WOT and WO timing. My 2200lb(boat only) 20' Hydra-sports will spin about 5900 with 1/4 tank of fuel. She spins a 14.5x19 SST and will hit a tad over 50mph on GPS. Have you done a compression check? She running on all 6? That boat should spin a 19 or maybe even up to a 21+ when set up right. 10" setback allows engine to be about 6"+ above keel, use a straight edge and see if she is high enough. Mine looks ridiculously high but works great.

If you find out setup is wrong and she now overrevs...let me know, I am looking for an 18".

Peter posted 07-07-2004 12:47 PM ET (US)     Profile for Peter  Send Email to Peter     
There is no standard 14 1/2 x 18P OMC propeller such as the aluminum or SST. Only OMC propeller in that size is a Raker. Does your propeller have the polished stainless steel appearance and vent holes in front of the blades?

A Raker, designed to handle surfacing, should be a good propeller for your application. An 18P Raker propeller is not a bad place to start on that boat but suspect that a 20P Raker would do better assuming there are no problems with the motor. If motor height can be adjusted, I would play around with adjusting that a little bit first to see whether the motor is set too high.

Smallfrye posted 07-07-2004 02:26 PM ET (US)     Profile for Smallfrye  Send Email to Smallfrye     
Good advice, I will start by adjusting the height. I began this set up with the prop I had, actually a Michigan # 389924, 14.5X18, and set the motor height to where I guessed the water tail would hit the lower unit. My guestamates are close but Peter's comments about slippage have me wondering if I'm too high ????
The motor is running very strong, I just have not pushed it beyond 4500. This was the first trip and not knowing if WOT was 5000, 5500 or 6000 I did not want to push the motor before the other mechanical issues ( motor height, prop size etc) where tuned.
I believe your both correct, this set up should push a 20-21" prop with little trouble. On my next trip, I will take a 20-21" prop and try it after I make a few up and down changes to the motor height.
Bigshot, your Hydro - Sport is of similar weight to this Guardian. Do you feel the 21" prop would reduce low end power too much for average cruising/ fishing use.
thanks again, Jim
Peter posted 07-07-2004 03:50 PM ET (US)     Profile for Peter  Send Email to Peter     
Your propeller should be an SST II 14 1/2 x 19P. Part No. 389924 is an OMC part number.

Based on my experience with the SSTs on a Whaler Drive, an SST or Michigan Wheel clone is probably not the ideal propeller for frothy water or a setback bracket set up. I suggest you experiment with different propellers such as the Raker, Mirage Plus, Revolution, or Power Tech, if you can.

Pick the pitch that will get you closest to, but not over, 6000 RPM at WOT as you are normally loaded. I would start with a 19P with the Mirage and Revolution, an 18P with the Powertech and Raker. The problem is that each prop will have its own optimal running height so you may have to fine tune that as well.

Bigshot posted 07-07-2004 03:52 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
My V is a 24 degree so it is not the fastest out of the hole(hence why i am looking for an 18 for heavy loads). She is no slouch but not a rocket like an 18' with a 150 on it.

So you have not GONE past 4500 but she will? Small...if that is the case you should have said so...this whole post is misinformation if you were only cruising at 3/4 throttle. At 4000 rpm I am running about 32+mph. At 4500 I am upper 30's. That 18" is screwy if only giving you 29mph or you are WAYYYY too low(doubt it). Raise that engine UP UP UP. Raise it until you can't make a wide U-turn at 30mph, then lower it until you are happy. You want her about 6" above where it normally would BS. The 19"SST is about equiv. to a 20" Michigan due to the double cupping. Go with a 21" if ya have one and see what she runs with a full tank and 3 people. If only getting 5300 or less, drop to a 19". If getting 5500 or so, then she will FLY when running a 1/4 tank and you will be in the mid 50's no problem. My 19" at 5900 runs about 50 on the nose...21" will get you 55 or so.

Bigshot posted 07-07-2004 04:00 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Ps...I would e running 52-53 if I did not have a t-top. Top does not really reduce RPM's as much as it adds slip at higher speeds due to drag. Kinda like hitting a gust of head wind in a car, rpms don't drop, just speed.

Peter is correct about props if you are dialling in your rig. I would benefit from something less "elephant ear" like as well but the newer SST's are not that round and 2moh aint worth $450 to me, especially if midrange suffers. You might find that 10" bracket to be detrimental on a Whaler, maybe not. Being it aint a speed boat, 10" is excessive and will change handling, not necessarily for the better if she is squirley at 50+ without a bracket. Sal says they are a tad tricky but his hull is different being a 1979 or whatever V20.

Lopaka posted 07-07-2004 04:33 PM ET (US)     Profile for Lopaka  Send Email to Lopaka     
I also have a 225 Ocean Runner on my 22' Law Enforcement Outrage. My hull is extra heavy and I am set up as a dive boat meaning I carry as many as 12 scuba tanks, gear and up to 6 divers. I also have 122 gals internal fuel. I get 5700-6000 rpm at WOT with no difficulty. I run a SS Johnson "Cyclone" 4 bladed prop 14.5 X 17. I have mounted a Doel-Fin on the cavitation plate as well. It runs like a raped ape...if you get my drift. As I am in rough water here in the Hawaiian Islands most of the time...the prop seems to have improved my performance.
Lopaka posted 07-07-2004 04:35 PM ET (US)     Profile for Lopaka  Send Email to Lopaka WOT I am getting at least 30-35 MPH.
timbaho posted 07-07-2004 04:49 PM ET (US)     Profile for timbaho  Send Email to timbaho     
I am running a 1997 200 hp OceanRunner with a 17 pitch Powertech on a 20' Guardian. The performance is almost exactly what yours is with 3 adults and 80 gals of fuel on board. Wide open throttle is 5600-5700 rpms ( depending on loading) at GPS calculated speed of @42-45 mph depending on sea conditions and trimming attitude. I would say your boat appears to be close to optimium unless we are both screwed-up.
timbaho posted 07-07-2004 04:51 PM ET (US)     Profile for timbaho  Send Email to timbaho     
Maybe I should clarify the 3 adults and 80 galllons of fuel are on MY boat!
Bigshot posted 07-07-2004 05:49 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
If he is getting that with a 200, a 18-19" should do it for a 225.
timbaho posted 07-08-2004 08:43 AM ET (US)     Profile for timbaho  Send Email to timbaho     
I agree with bigshot
Smallfrye posted 07-19-2004 10:31 AM ET (US)     Profile for Smallfrye  Send Email to Smallfrye     
just a partial update; I moved the motor up and down one 1.5" in each direction and at the higherst level I get the best handeling performance. The porposeing I experianced at the lower settings has been minimized and the trim tabs are now only needed for fine tuning. Your right Bigshot, the motor is so high over the transom it looks like the transom has been cut out from under the motor. I only have another inch or two before I reach the max height for this set back bracket.
Speed has not improved much. WOT at 6000RPM's is bringing about 39-40mph SOG. 4000RPMs crusing speeds are still 23-24MPH SOG. These are approximate since I didn't pay much attention to tide fow, but it wasn't significant.
The prop is going into the shop today to determine the actual pitch, cupping and to check the condition of the hub. Based on the speed, I expect to find this 18" prop may have been changed more than is marked on the hub.
Question; can a hub be spun or loosen to the point that slippage occurs but not total failure? I seem to be slipping and I can't belive the prop design can have this much impact.
Any comments are welcome.
Bigshot posted 07-20-2004 12:24 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Let's the 6k WOT mashed to the dash or do you still have throttle left? Has anyone checked tach accuracy or make sure you are mashed to the dash?
Smallfrye posted 07-20-2004 03:49 PM ET (US)     Profile for Smallfrye  Send Email to Smallfrye     
6000RPM's is WOT, running for 10-15 seconds to stabilize and measure SOG from the GPS. I also wonder about the tach, but have not checked it yet.
I discussed this issue with a performance prop mfg. and several guys who build and race hi-perf outboards. Both seem to agree the problem is not any one thing. The prop, although marked as an 18", is actually a little lower and had very little , if any cup. This is being modified to 19" with cupping. The performance guys suggest lifting the moter another 1/4- 1/2 inch to determine the max height. From these findings they will work their majic.
The big issue seems to be the T-top. The angle of this particular top is high in the front and may be the cause of the drag/ slippage (35%). After running the new prop, we'll remove the cover and compare perfomance w/ & w/o the added drag.
Sal DiMercurio posted 07-20-2004 10:57 PM ET (US)     Profile for Sal DiMercurio  Send Email to Sal DiMercurio     
Jim, I run an older V20 [ 1979 ] so the hull is way different.
I have to agree with Peter & Bigshot, they have given you excellent advice.

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