prop recomendation

[Akros]

I just bought a 1992 18ft Reinell bowrider with cobra/4.3 180hp. I would like to pull a 160lb skier once in a while. I think I want a 14x21 3 blade but would like some opinions. I am hoping for close to 50mph with 2 people.

Thanks

 

[Silvertip]

Re: prop recomendation

How do you know you don't already have an optimum prop. You provided no data for us to make a judgement. Every boat, every load, every engine/drive combination has a different prop requirement. There is no such thing as a "standard" prop. Read the sticky at the very top of this forum titled "Read This First".

 

[Akros]

Re: prop recomendation

Sorry about that!
The current prop is 15R17mwc 3 blade aluminum and the boat tops out at 37mph at 4500rpm with 2 people and 25mph at 3000rpm. It weighs 1960 lbs. I knew that seemed slow for this boat compared to other similar boats I have seen tested so I didnt bother to apply full throttle because I didnt want to redline the engine. I double checked the speedo with GPS and it is accurate. Similar boats tested on Boattest.com are using a 14x21 from the factory so I assumed it would be a good prop for mine.

 

[junior1113]

Re: prop recomendation

so it could go higher than 4500 at wide open throttle? that motor would perform its best at about 4400-4600. i believe in 4 blade props. they are way better in most aspects esspecially pulling power. not to mention stronger reverse, faster hole shots, can run on plane at lower speeds, hold water better in rough conditions, i even gained mph. just changing from 17 to 21 will result in ABOUT 800 RPM reduction. right now slip is high. i'd put a 4 blade 17p on and see. probably be happy. what is wot rpm?

 

[Silvertip]

Re: prop recomendation

Unless you make a wide open throttle run with what you consider an average load you have no idea which direction to do with a prop. You don't need to run for miles at WOT to determine this. A short run watching the tach and speedo (preferably GPS) will tell you all you need to know. The engine will tolerate a short blast at 5200 or a little more if that's what happens. But until you know what the "current" wide open throttle rpm is with the current prop, you don't know which way to go or whether you already have the best prop. Just make sure you do the testing with what you consider an average load. Speed will be whatever the prop provides that puts WOT rpm at the top of the manufacturers recommended band.