1989 Cobra Outdrive Prop Question

[tallguy63]

I have a 19 ft '89 Bayliner Capri with a 3.0 OMC I4 with a Cobra Outdrive. The original prop is 13 3/4 X 15. I want to replace the prop with the same one, however I am having problems figuring out which hub assembly I need. I do not know the exact model of the boat because it came with no paper work. I also noticed that other sites have various splines and hp rating for what I think is the same motor/outdrive combo. Is there a way to exactly know what hp my motor has and how many teeth are on the spline? The boat very well might not be what the owner said it was. Any information about the designation or model number for the boat would be great. Does anyone know of anywhere where I can run the VIN or engine number or outdrive number to get the correct information? Any help would be great

 

[Dhadley]

Re: 1989 Cobra Outdrive Prop Question

That should be a "Joint Venture" drive. There were a couple of drives used on that set up. One had a V4 style OMC propshaft that will have 13 splines. The other drive had a V6 style shaft and had 15 splines. If someone has replaced the drive with an SX style, the shaft will have 19 splines.

Count the splines and let us know.

Is the current prop a 3 or 4 blade?

 

[tallguy63]

Re: 1989 Cobra Outdrive Prop Question

It has a three blade on it currently. It would make sense that you describe it as a joint venture because the outdrive says "OMC Cobra" on it. I will take the prop and hub off this weekend weather permitting. Will the number of splines be sufficient to get the correct hub/prop?

 

[Dhadley]

Re: 1989 Cobra Outdrive Prop Question

Yes, it will.

 

[tallguy63]

Re: 1989 Cobra Outdrive Prop Question

Got the prop off this weekend. It slid off effortlessly with the hub and all. 13 tooth spline. I think I will be purchasing a 12 3/4 X 15 in hustler prop from iboats in the coming week, that's what was on it before. any questions or comments would be appreciated.

 

[walleyehed]

Re: 1989 Cobra Outdrive Prop Question

That 12.75X15 Hustler has a very small blade area as compared to the 391198 OMC, 13.75X15, which is a very good design for an I/O.
If you run the Hustler, you may want to run it through their "Test prop" program because I don't think you're going to like the low end, and lack on top that it will give.
How was the RPM and speed numbers with both props?

 

[tallguy63]

Re: 1989 Cobra Outdrive Prop Question

the original prop was torn up pretty bad when we drove it. it has numerous chunks out of it the size of my thumb nail and not one smooth outer edge. it turned maybe about 5200-5400 if i can remember and got us up to about 36mph. It was a 13 3X4 X 15. I really do not know that much about props and I really just wanted to get another prop of the same size and pitch which i thought i was. I don't know anything about blade area and really just want a prop the same size as the stock one for now, which i thought i was buying. any other info about which prop to get from anyone would be great. thanks for the info walleyehed any more would be appreciated.

 

[Gary H NC]

Re: 1989 Cobra Outdrive Prop Question

If you want the exact same prop your local Johnson-Evinrude dealer could probably find you one.Might be expensive compared to the other props.
My old OMC Cobra had the OMC Raker prop that did a great job.It was actually better than a new Stiletto stainless i bought in the same size and pitch.I put the original back on it.

 

[tallguy63]

Re: 1989 Cobra Outdrive Prop Question

The original one is all but useless, it would need some holes filled and some serious grinding in which case would probably change its original dimensions. I was under the impression that 13 3/4 X 15 props were all the same dimensions. How can i find the exact dimensions of the original, including blade area and get another one as close to it as possible? I understand that no prop is the "right prop," but i do want to get one as close to the original as possible. any help would be appreciated.

 

[Gary H NC]

Re: 1989 Cobra Outdrive Prop Question

Is there a part number on the hub? Should be a 6 digit number or a seven digit starting with a 0,also should be a logo with a M with a circle around it if its the oem prop.

 

[tallguy63]

Re: 1989 Cobra Outdrive Prop Question

First off, I messed up pretty good. In one of my previous replies I wrote that I was purchasing a 12.75 X 15 prop when in reality it is s 13.75 X 15 prop which is the exact same dimensions as the original prop. My apologies walleyehed. In any case, would this prop still be a manageable choice for my application? I cannot get it in the prop exchange program, but other prop calculators suggest a prop around 15 X 21 or 23. would a 13.75 X 15 have the same blade area as the original? or should i got with something bigger? thanks for all your help guys

 

[Dhadley]

Re: 1989 Cobra Outdrive Prop Question

Are you OK with turning that 3 liter 5200-5400?

 

[tallguy63]

Re: 1989 Cobra Outdrive Prop Question

i am not 100% sure of max rpm with the original prop. the book quotes it around 4800...so that might be a better estimate. all i really want is an idenitcal or close to identical original prop for the boat. are props with identical diameter and pitch completely identical or do they still differ in other dimensions from one another?

 

[Gary H NC]

Re: 1989 Cobra Outdrive Prop Question

I think a 21 pitch would be way too much for a 3.0 engine.