93 Johnson 60 hp Max RPMs

[VBtravisD]

I am in the process of redoing a 15.5' skiff. I got a 93 Johnson 60 hp motor along with it. I purchased a Seloc manual and the max rpms for this motor is listed as 5000-6000 at WOT. To me, that is a huge range. Can someone help me narrow that number down a bit?

Thanks,
Travis

 

[Tim Frank]

Re: 93 Johnson 60 hp Max RPMs

To your motor it is not a huge range....
The WOT RPMs will be dependent in a number of factors including prop, your boat, the load etc.
You size the prop to give you as close to that range as possible under most, if not all, conditions.

 

[VBtravisD]

Re: 93 Johnson 60 hp Max RPMs

Thanks for the reply Tim! So tell me if I am getting it correctly. I totally understand how prop and load will effect my rpms. But I want the motor to run between 5-6K most of the time? Would it be safe to say that 6000 is the upper limit and it would be better to run it at something like 5600? or 5800?

Thanks for any help you can throw my way! I am used to a small tiller handle with the throttle pinned and me grinning.

 

[Tim Frank]

Re: 93 Johnson 60 hp Max RPMs

You may want to do research in the prop section if you want a detailed explanation....I understand enough to know that my rig is OK.
If you don't have a tach, you are guessing....if you do, and the RPM at WOT is in the band, you have the right prop for what you are doing. Change parameters and you may need to change props.
If you are good at WOT, other throttle settings should also be OK....whatever the RPM.

 

[Solittle]

Re: 93 Johnson 60 hp Max RPMs

Thanks for the reply Tim! So tell me if I am getting it correctly. I totally understand how prop and load will effect my rpms. But I want the motor to run between 5-6K most of the time? Would it be safe to say that 6000 is the upper limit and it would be better to run it at something like 5600? or 5800?

Thanks for any help you can throw my way! I am used to a small tiller handle with the throttle pinned and me grinning.[/QUOTE

There is nothing majic about max rpm at WOT. Racing engines are tuned to go much higher.

You want to use a prop that will get you this max rpm which means at lower rpm you will not be lugging the engine.. Most engines run at their economical best at 80-90% of this majical number. For your 15.5' skiff I'm going to guess that your optimum run all day rpm is going to be around 4-4,600 rpm.