help please

[spav816]

what prop do I need for best performance of a 35HP 1957 Evinrude mounted onto a 18FT mod-v alum. boat. I'm going to be using it for fishing on rivers below hydro dam so it will need enough power to fight the currant

 

[hwsiii]

Re: help please

Welcome to the forum spav. If you are willing to fill out a form and do some trial runs and give me the rpm and MPH from that, I can help you. I am sorry, but I am tired of trying to help people that won't take the time to do it right, but just think there is a magic fix with no effort involved to correctly prop their boat. And then they never come back and tell you exactly how it worked for them, so I now require as much effort from the person requesting help as much as I require from myself. If you are willing to do this I am willing to help you.

H

 

[steelespike]

Re: help please

Best way to pick a prop is to post the present performance figures.
prop size,max rpm and speed.Is the boat full rigged live well full floor
remote steering built in tank etc. ? ? approximate typical loaded weight.
If no tach check out the tinytach.Reasonable easy to install and will fit any 2 cylinder 2 stroke.gps for speed is best but a speedo will do.

 

[spav816]

Re: help please

ok guys I will try to get the info you need...... The boat is a landau model 1870 full floor 2 live wells front and back deck. Remote steer, but I don't have a tack or speedo. I don't have any gages on the boat. I'm new to boating I have not had a boat in 15 years. I'm sad to say but I forgot most of what I learned. That boat was 3 wives and 2 kids back. I got a wife know that loves to fish so she let me get this boat without much of a fight........

 

[steelespike]

Re: help please

Selecting a prop without a tach is a real crap shoot.If you tell us what size prop you have now it will help a little.Numbers are usually on the outside of the hub something like 12 X 12 (diameter X pitch).Pitch is the key number.
If no numbers a prop shop can measure it for you.If the prop is dinged up you should have it repaired anyway.Its important that the motor operate within its rpm range for economy and its health.The Tinytach is simple to install and costs about $40.
I think a 11" pitch would work for your boat.If a prop is too low a pitch you can still use it and simply stay within the rpm band with the throttle.
If a prop has too much pitch (higher number).the motor will lug and be sluggish.and you shouldn't use it.Thus the need for a tach.
A motor can perform reasonbly well and still be lugging. over reving and lugging are both bad for the motor.But you can control over reving until you can select a better prop.