Prop advise needed

[willi14]

Hello ... new member here. I am in need of some prop advise. Here is what i got. I have a 14 ft glasstream fiber glass boat with a 40 hp mariner oil injeted.
the boat was bought for me by my wife as a gift. The engine serial plate is missing so no id is known by me. She was told that the 40 hp mariner engine came off a pontoon boat. The prop on it is a 12.25 X 9p. The spline count is 13. The lower unit is about 16" below the bottom of the boat. I need a fuel pump and a new prop.
My question is what prop can i use for this motor since it is not on a pontoon any more? With the prop i have it ran 16 mph on my fish finder. I dont know what rpm it runs at. The boat is rated for a 70 hp max.
Any suggestion?

Thanks
Willi

 

[hwsiii]

Re: Prop advise needed

Would you take a piture of the lower unit from the side with a straight edge and let us atually see how low the anti ventilation below the keel.

H

 

[willi14]

Re: Prop advise needed

Will do

Thanks
Willi

 

[hwsiii]

Re: Prop advise needed

You are welome Willi.


H

 

[willi14]

Re: Prop advise needed

The anti ventilation is 1 1/2 inches below the keel. I attached a couple pics of the lower and one of the whole engine in case anybody can give me an idea of year so I can find a new fuel pump.

thanks again for all your help

Willi

 

[hwsiii]

Re: Prop advise needed

Willi, you need to move it up 2" higher than it is.


H

 

[willi14]

Re: Prop advise needed

Thanks for the reply. Ok I will move t up 2 " and that will make it 1/2 " above the bottom right? After your request I kinda thought it might be low. So after I raise it what would you suggest I use for a prop. The same or something different? I use it for fishing, 2 people, 6 gallon fuel, boat is under 600lb dry, 14ft, fiberglass. Dont want or need the best but something good.

Thanks
Willi

 

[hwsiii]

Re: Prop advise needed

Willi, I need to know the gear ratio of the lower unit and here is how you do it.

7. HP and gear ratio of motor IMPORTANT
If you don?t know the ratio, you need to pull the plugs out and put a piece of tape across the prop and the lower unit and then cut it between the prop and the housing then do the same thing on the motor and turn the motor until the tape lines up with each other on the prop, it is easier if two people do this, so one can watch the prop while the other counts the revolutions of the motor.

Then I will be able to tell you what prop to buy.


H

 

[willi14]

Re: Prop advise needed

Once again thanks and i will do that then get back to ya

Willi

 

[willi14]

Re: Prop advise needed

Two revolutions of the flywheel to the tape marks = 1 revolutions of the prop tape marks

40 hp Mariner oil injected
Willi

 

[Tacklewasher]

Re: Prop advise needed

Willi, I need to know the gear ratio of the lower unit and here is how you do it.

7. HP and gear ratio of motor IMPORTANT
If you don?t know the ratio, you need to pull the plugs out and put a piece of tape across the prop and the lower unit and then cut it between the prop and the housing then do the same thing on the motor and turn the motor until the tape lines up with each other on the prop, it is easier if two people do this, so one can watch the prop while the other counts the revolutions of the motor.

Then I will be able to tell you what prop to buy.


H

Hey.

You got your "c" back.

 

[hwsiii]

Re: Prop advise needed

Takle, nooo not yet, just been using spelling orretion. LOL

Willi, you need a 13" pitch prop and that ought to work well for your setup.


H

 

[willi14]

Re: Prop advise needed

A 13 inch pitch prop. Could you suggest one that you refer to. A inexpensive one at that. Thank you for all the help you have givin me.

Willi

 

[hwsiii]

Re: Prop advise needed

Willi, is it flat bottomed at the stern.


H

 

[willi14]

Re: Prop advise needed

Yes it is flat at the stern. It steps down to a flat surface. One of the pics i posted show the steps to flat.

Willi

 

[Tacklewasher]

Re: Prop advise needed

Takle, nooo not yet, just been using spelling orretion. LOL

Willi, you need a 13" pitch prop and that ought to work well for your setup.


H

Alright.

This is getting silly.

We need to start a collection for a new keyboard for hwsiii.

 

[willi14]

Re: Prop advise needed

I dont clearly understand just what a " Pitch Prop" is. Can somebody please explain just what a pitch prop is?
Thanks
Willi