4 Blade Prop on a 9.9

[hct4all]

I have a 3 blade prop on the 9.9 and I only get about 3900 rmp. I have tried 3 different sized 3 blades. Will the 4 blade prop advertised in Cabales heavy boats help at all. The boat is a 16' Sea Nymph FM. I even put a minijacker jack plate on it. Is it wort getting another prop?<br /><br />I get about 6-8 mph gps Never planes.<br /><br />Thanks,<br /><br />Rick

 

[DHPMARINE]

Re: 4 Blade Prop on a 9.9

To my thinking 9.9 is a little small for most 16 foot Sea Nymphs.Had a similar problem with a 9.9 on a 16 foot Sylvan.These aren't light boats.Twin 9.9s has a sweet ring to it.<br /><br />DHP

 

[Moody Blue]

Re: 4 Blade Prop on a 9.9

Thats alot of boat for a 9.9. Most rigs that size run 25-40 HP. You are asking alot from that motor and will wear it out prematurely running at only 3900rpm with such a heavy load. You might try a shorter pitch prop to bring the rpm's up to where they should be but that will not help alot in the top end speed. What props have you tried ?

 

[hct4all]

Re: 4 Blade Prop on a 9.9

I have tried a 8,9, and 10. 10 gave me the highest RPMs. I live in a very backward state. All the lakes in my area(The Southwest) - Are 9.9 limit. Do y'all think the 4 blade prop will help?

 

[Reel Poor]

Re: 4 Blade Prop on a 9.9

the 8 should have yielded more rpm than the 10

 

[hct4all]

Re: 4 Blade Prop on a 9.9

Its been a while, I may have gotten that backwards - Sorry!!

 

[mjbrueck]

Re: 4 Blade Prop on a 9.9

On mine ('02 9.9 4-stroke), the only 4 blade Mercury makes is a 9.75x6. 3900 rpms with an 8" pitch would give you 5200 rpms with a 6" pitch, assuming same prop efficiency (which they won't be, but should be reasonably close).<br /><br />On your boat, it won't help much (if any) with speed, but your motor will be much happier.