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Posted 1/25/2008 6:13:31 PM


Grouper

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Took my boat out the other day to see if my impeller install worked.  Ended up taking a good little trip.  I noticed something when throttling while coming out of the hole and onto plane.

While the boat is coming up and I'm still throttling, the rpms amp up and it doesn't feel like the props are pushing, and then it kicks in and goes.

Why????????

-former overNunder-

I support GulfSide Boat Worx...boat cleaning/detailing, bottom cleaning, zinc/anode changing and teak work. Lic. and Ins       251-923-9166
Post #52734
Posted 1/25/2008 7:32:43 PM


Sailfish

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Just a guess.

Prop pitch is to high and it's not bitting the water enough.




---------------------------------------------------------
"Just cause it's new, doesn't mean it's worth a Damn."

Pensacola, Fl

Custom 23ft Mako Pilothouse w/ twin DF-140 Suzuki's
162 Scout w/ C-90 Yamaha







Post #52788
Posted 1/25/2008 7:40:41 PM


Grouper

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Ok got another question.

I've been on boats before and be running on plane and all of a sudden if stops engine revs way up and you can't go anywhere. 

I was told that had something to do with the shear pin or the packing in the prop.  Could the packing in my props being going bad.

-former overNunder-

I support GulfSide Boat Worx...boat cleaning/detailing, bottom cleaning, zinc/anode changing and teak work. Lic. and Ins       251-923-9166
Post #52792
Posted 1/25/2008 7:48:55 PM


PFF Moderator

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Could be spun hub?!?!?

Capt. Tony Blanton

Certified Marine Technician

Powerpole dealer and Outfitting specialist

SAMS SA Marine surveyor

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Post #52802
Posted 1/25/2008 7:50:21 PM


Grouper

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is that a major problem and what could've caused it

-former overNunder-

I support GulfSide Boat Worx...boat cleaning/detailing, bottom cleaning, zinc/anode changing and teak work. Lic. and Ins       251-923-9166
Post #52805
Posted 1/25/2008 8:17:26 PM


Trigger

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I spun a hub before. It starts out slipping a little under high power and before long I was lucky to get 5 mph out of it.  Eventually all your motor will do is make noise.  They can be repaired at one of the local prop shops.  I got mine fixed at ACCU prop for I think about 80-90 dollars.  They will inspect it first to make sure the old one is bad.  There was no doubt on mine, the black rubber was about half gone.  Some of the things I'm told that cause it are old age, hit something in the water, and improper propeller pitch.  I'm no expert, but that is my experience.

Cape Horn 21
Post #52819
Posted 1/25/2008 8:27:40 PM
Sailfish

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Could be a hub, but I have never seen a hub slip and then grab. Usually it is like orion said, it goes from bad to worse. Sounds to me like air is getting into the prop causing it to slip and then as the boat starts to level it grabs water again. Has anything else been done to the boat recently?

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Located in Navarre just north of the bridge.


 

Post #52823
Posted 1/25/2008 9:37:44 PM


Trigger

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What kind of motors? Do the engine rpms increase but the boat just won't go? Or are the engines bogging down and just not making power?

The Maintenance Shoppe LLC
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Post #52857
Posted 1/25/2008 9:38:37 PM


Grouper

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Nope, just changed a t-stat and took the water pump apart to change the impeller. 

-former overNunder-

I support GulfSide Boat Worx...boat cleaning/detailing, bottom cleaning, zinc/anode changing and teak work. Lic. and Ins       251-923-9166
Post #52858
Posted 1/25/2008 9:43:11 PM


Trigger

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While the boat is coming up and I'm still throttling, the rpms amp up and it doesn't feel like the props are pushing, and then it kicks in and goes.

Why????????


Can you describe in further detail?
Read my questions.


The Maintenance Shoppe LLC
SALES, INSTALLATION, AND SERVICE
*RAYMARINE *GARMIN *FURUNO *LOWRANCE *KENWOOD *BAZOOKA

Your boat repair and customization headquarters
1 mile west of Scenic Hwy on Creighton Rd
4048 Creighton Rd.
Pensacola, FL. 32504
850-221-6789
http://www.themaintenanceshoppe.com
Post #52860
Posted 1/25/2008 11:32:58 PM


Sailfish

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Here's how to check for a Spun hub.

Use a bright colored Sharpie Marker.

Make a mark on the edge of the prop and hub. This will be what is called a "Witness Mark" Those marks will be aligned with one another.

Go run the boat and hammer the throttle. You don't have to take it far from the dock to do this.

Bring the boat back to where you can get a clear view of these marks. If they are misaligned your hub is spinning and needs to be replaced.


---------------------------------------------------------
"Just cause it's new, doesn't mean it's worth a Damn."

Pensacola, Fl

Custom 23ft Mako Pilothouse w/ twin DF-140 Suzuki's
162 Scout w/ C-90 Yamaha







Post #52910
Posted 1/26/2008 5:38:12 AM
Snapper

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Same thing happens on my boat.  150 Zuk 2 stroke pushing 20' deep V.  Sometimes when I go from very slow to firewall, acts like it grabs then rpms shoot up.  Come back just a little on gas, everything comes together and we get up and go.  Hub is not spun, motor is mounted with cavitation plate approx 1-2" below keel.  It sounds and feels like cavitation, but I don't think the prop is pitched wrong as the rpms at full throttle are right on the money.
Post #52934
Posted 1/26/2008 6:59:29 AM


Snapper

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Alright guys this one I know. I was a quicksilver propeller franchised and "factory trained" (I went to a Merc sponsored school for about three consecutive years) for 15 years. His problem is almost surly cavitation. The spun hub problem is almost always as you are coming out of the hole and the boat il absolutely NOT plane off. He needs to check to see if a bolt head on the lower unit is sticking out further than it should. This causes a low pressure are to form behind it. Water boil in this area and allows the vapor to stream back and grow large enough to cause the prop to quit pushing water . A large bubble will form until he comes off a plane and slows down until clean water gets to the prop. He should check his trim angle as he could be pulling air around his anti cavitation plate which would do the same,  The other place gas could be leaking into the water stream causing the problem would be if he put his thrust washer which goes in front of the prop. This will allow exhaust gas to leak out and fowl the blades until enough forward speed is achieved to collapse the gas bubble onto the hub and allow the blades to bite.

   Now as far as a prop breaking loose while under way. That is usually caused by grass wrapping around the front of your lower unit and again causing the low pressure steam thing to happen. If it is happening while in a tight turn then you can have more cup added to your prop and that will end most cavitation problems caused by trim hight or breaking loose in the turn.  You also need to check and be sure your transducer or livewell pick up is not too close to the propeller. This will also cause water vapor to stream down and cause your prop to cavitate. I can fix your problem as I still have the tools for cupping props and used to do alot of custom race work on propellers. I don't mind helping you guys out.  

Post #52940
Posted 1/26/2008 1:37:55 PM


Grouper

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thats some hard core info.  preciate guys.

If it helps my motors are volvo pentas 130 i/o.   Prop size is 14.25x23R  S and 14.25x23L  S

I have no idea what that means.  

-former overNunder-

I support GulfSide Boat Worx...boat cleaning/detailing, bottom cleaning, zinc/anode changing and teak work. Lic. and Ins       251-923-9166
Post #53116
Posted 1/26/2008 2:05:36 PM
Sailfish

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That shines a different light. I think we were assuming, I know bad thing, that you had removed your lower unit to change your impellers. But that obviously is not the case. And did the RPM on both engines increase?

_________________________________________________

Dealer for www.stickitanchorpins.com and Sea Tow

Located in Navarre just north of the bridge.


 

Post #53129
Posted 1/26/2008 5:34:38 PM


Grouper

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  man I don't know, I forgot to look at the tachometer when in did it.  My instinct was to turn around and look back to see if anything is obvious to why its reving up.  It sounded like it was just one motor.

The props do have a couple of minor dings and I did get into some shallow water while running.

-former overNunder-

I support GulfSide Boat Worx...boat cleaning/detailing, bottom cleaning, zinc/anode changing and teak work. Lic. and Ins       251-923-9166
Post #53204
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