What size prop should I use

matt88

Petty Officer 2nd Class
Joined
Mar 17, 2009
Messages
160
I have a two stroke 30hp tohatsu on a 16ft flat bottom jon boat. It runs ok now but Im sure the prop is robbing a lot of power from me. On the gps it runs around 22mph and thats with two people and gear of about 500 pounds over the boat weight. I dont have a tach so I am just trying to get a ball park figure on what size,pitch prop I need. Right now I think it has a 9 or a 10 pitch on it with a 10in diameter.
 

steelespike

Supreme Mariner
Joined
Apr 26, 2002
Messages
19,069
Re: What size prop should I use

Its really difficult to make a prop selection without a tach.Though speed by gps the best speed indicator speed without rpm doesn't tell us much, rpm alone as well. We need details on the boat,full dress,bare bones?
Description of overall performance.I think we can improve your speed.
A tinytach is reasonable and easy to install.Guessing pitch is no help as well.
Numbers should be on the barrel or under the prop nut.
Changing props without the right info could be suicide for your motor and produce poor performance.
 

matt88

Petty Officer 2nd Class
Joined
Mar 17, 2009
Messages
160
Re: What size prop should I use

Will try to get a tach asap. The boat is a 16ft flat bottom jon with a fairly thin fiberglass floor,carpet,and a couple of seats. I plan on adding a rear deck,etc,etc,later on but this is what I had when it ran 22mph. I have checked my prop for numbers but am not having any luck. I know this wont help but compared to other props I have seen it doesnt look very aggressive as far as pitch is concerned and it has zero rake. Its been beat up on and I had to straighten it out the best I could when I first bought the motor. The only new prop that I have been able to find is one on this site with a 9" pitch. Its an older model tohatsu with the shear pins. Someone had told me that he had the same rig with a 4 stroke 30hp and ran 28mph. I guess the tach will tell me the rest of the story. thanks
 
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