Prop Suggestions for a Nissan 9.9 hp 2 stroke

KillerTree

Recruit
Joined
Apr 18, 2016
Messages
1
I have a 9.9 hp Nissan 2 stroke on a 14 foot semi-V hull. The motor runs good but I am losing RPM at WOT I am certain the hub in the prop is slipping as it only drops RPM after I turn sharp and the RPM's wont come back from time to time. The prop I have on it is a 3 blade 9.25 dia. 9" pitch. I've had that prop on this motor for 5 or 6 years and it has served me well. If I am by myself the boat would plane out just fine. I am now married and very rarely ever go by myself fishing anymore and with 2 people in the boat the thing is a dog and I can't get it to plane out even before the hub was slipping. I was wanting any info/ recommendations on a prop that would get this boat to plane with 2 people in it. I was thinking maybe trying a 4 blade prop but I just don't know. I am not really looking for top end speed I would just like something to get me on top of the water instead of bulldozing the water.

Any help is greatly appreciated.

Thanks,
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
First of all I think a 9.9 should plane easily with 2 aboard.Years ago we had a 14 ft Crestliner with a 10 hp Johnson
It planed easily with about 200 lbs of teenagers in the back seat.Tell us about the total load.Is it a bare bones utility?
Hub slipping would result with higher rpm and slower speed.And usually hub slip would be total requiring you to slow until it grabbed then
keep the power lower or it would slip again.In my opinion a 9" should be ideal on a bare bones utility.
Is the prop in good shape? Pics? The anti vent plate (just above the prop) should be about even with the bottom of the transom.
Is the motor in excellent tune, Is the throttle operating correctly?Are the plugs right
 

Sea Rider

Supreme Mariner
Joined
Sep 20, 2008
Messages
12,345
Discard firstly you already have a spun hub sith a hub slip test. You're underpowered with a 9.9 HP running a 14 footer. What you can do is pass that 2 strokes 9.9 to a 15 HP for peanuts costs, go for a wot spin lightly loaded and check achieved max wot rpm with current prop along an induction tach. You can even maximize a prop to suit well boating with family, a lower pitch prop from current one will make the trick. What's the current number stamped on prop body, 9-10 ? Your OB could be sitting slight high on transom or be badly trimmed, that's why losing rpm when at close turns, aereation issues.

Happy Boating
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Would be great to know your lightly loaded wide open throttle rpm and gps speed.
gps speed would help if no tach.
You should have a tach if your going to change a props.
 
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