Best prop?

[Benj1983]

Any help with this would be much appreciated, I have a ribeye 650s which used to have a 150hp Yam fourstroke. Unfortunately it had a head problem, I went down the route of replacing it with a 2013 mariner 2 stroke optimax. The prop that came with the engine at full throttle only allows me to get the rpm up to 5030 and 32 knots! Obvoiusly a two stroke has its power high up the rev range, and with the old four stroke in good conditions I would easily see over 40 knots flat out on the Gps. I was hoping with the 2 stroke even more. What would be peoples suggestions be on past or present rigs. Thanks in advance Ben

[andrew_ireland]

Originally Posted by Benj1983

Any help with this would be much appreciated, I have a ribeye 650s which used to have a 150hp Yam fourstroke. Unfortunately it had a head problem, I went down the route of replacing it with a 2013 mariner 2 stroke optimax. The prop that came with the engine at full throttle only allows me to get the rpm up to 5030 and 32 knots! Obvoiusly a two stroke has its power high up the rev range, and with the old four stroke in good conditions I would easily see over 40 knots flat out on the Gps. I was hoping with the 2 stroke even more. What would be peoples suggestions be on past or present rigs. Thanks in advance Ben

Usually a prop with a higher pitch, will give a better top speed. With revs that low perhaps the prop is too large (diameter) a smaller prop will allow the engine to rev higher it's all about playing with it and testing untill u get it perfect for the boat and engine.
Regards
Andrew

[paintman]

Usual advice:
Look up the engine manufacturer's Wide Open Throttle (WOT) range for that engine.
Take your boat out with its normal load & make several runs at WOT & note the achieved RPM.
Once you have that figure you can then look at props that will give you nearer to what you are looking for whilst staying within the WOT range.
Mercury - and others - have apps you can enter your details into that will give their suggestions: https://www.mercurymarine.com/en/us/...tor/#/step-one

[jeffstevens763@g]

https://www.propeller-shop.eu/propeller-info/

might help

[Jeff]

Originally Posted by Benj1983

Any help with this would be much appreciated, I have a ribeye 650s which used to have a 150hp Yam fourstroke. Unfortunately it had a head problem, I went down the route of replacing it with a 2013 mariner 2 stroke optimax. The prop that came with the engine at full throttle only allows me to get the rpm up to 5030 and 32 knots! Obvoiusly a two stroke has its power high up the rev range, and with the old four stroke in good conditions I would easily see over 40 knots flat out on the Gps. I was hoping with the 2 stroke even more. What would be peoples suggestions be on past or present rigs. Thanks in advance Ben

What pitch is your current prop ? Based on your current revs, you would most likely need at least 2" less pitch to get into the 5600-5750 range - assuming the same model of prop. Its probably a laser II ??