think i have prop trouble

matt88

Petty Officer 2nd Class
Joined
Mar 17, 2009
Messages
160
At about 75-80% throttle with 2 people I can run anywhere between 18-20mph depending on the water,wind,etc.. At wot I can hear the engine rpms increase but no increase in speed on the gps. Also if I put my hand on the engine while running theres a high frequency vibration. You cant feel it from the tiller handle or just sitting in the boat so its not bad Im just worried this can cause some serious engine trouble in the future if I dont get it fixed. Does this sound like an unbalanced prop? When I first got this engine the prop was damaged badly and I straightened it the best I could myself and I have been planning on sending it off to a shop that does prop work so it will be right but I just noticed this vibration over the weekend and was hoping someone could confirm my suspicions. The engine is a 2 stroke 30hp tohatsu and its on a 16ft flat bottom jon boat with full dress,seats,lights,livewell,carpet,etc.. thanks.
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: think i have prop trouble

Does this sound like an unbalanced prop? When I first got this engine the prop was damaged badly and I straightened it the best I could myself
You can never straighten a messed up prop without having the correct equipment to do it, sorry. You could probably spend your money better buying a new cheap aluminum prop here and just save thye old one as a spare, that is what I would do for the difference in price.

H
 

matt88

Petty Officer 2nd Class
Joined
Mar 17, 2009
Messages
160
Re: think i have prop trouble

I realize that. Thats why I said I was planning on sending it off to have a shop fix it for me. My question was whether or not the vibration was caused by the prop or something else. I think its probably the prop but was wanting input by someone who had experienced these symptoms before. It did help though when I tried to straighten it myself. It wouldnt even plane out the boat before I tried to fix it,but I realize it has to be balanced and set to certain specs. Thats why I made it a point to say I was sending it to a shop. The only prop that I can find is a 9" pitch and Im sure that I will need atleast a 10 or 11 with my current setup. Can you tell me where I can find a 10 or 11 pitch prop for an 82 model tohatsu with the shear pin and without the through prop exhaust. I know I could buy the 9 and have it repitched to an 11 but why pay for a new prop and then pay to have it sent off when I could just send my old one off??
 

junior1113

Senior Chief Petty Officer
Joined
Jan 29, 2009
Messages
763
Re: think i have prop trouble

vibration can be caused by bent prop shaft or bearings. i would check it for trueness
 

hwsiii

Commander
Joined
Jan 25, 2009
Messages
2,639
Re: think i have prop trouble

Matt, what I was trying to say was do nothing to the old prop, just have it for a spare only in case of complete failure of the other prop. Buy a new one, shouldn't cost over 60 to 80 dollars and use it, repairing the old one usually cost about 50 dollars or more, so you have a new one for a few dollars more, in perfect shape.

I ran your numbers with my best guesses for total boat weight and the gear ratio on your boat. I show about 1,200 pounds and a 1.92 gear ratio, if this is wrong by much my numbers will be wrong. I show you will need a 12" Pitch prop. I hope you have luck finding it.


Boat and Motor

Matt88BoatandMotor-1.jpg


Prop Picker

Matt88PropPicker-1.jpg


H
 

matt88

Petty Officer 2nd Class
Joined
Mar 17, 2009
Messages
160
Re: think i have prop trouble

Thanks for the info. Those numbers do look pretty close. The one prop that I could find was here on iboats for about 127.00 and it was a 9 pitch. So I figured I would probably have almost 200 bucks in it getting it dialed in. Does anyone have any information on where I might be able to purchase a new prop for my make/model engine? Thanks again for running those numbers. If I do find a new prop I will be going with a 12 pitch.
 
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