A stupid question about planing?

[oshkoshboating]

Re: A stupid question about planing?

so if I give you the info, you then run it through your document and the proper pitch for the propeller is calculated?

 

[j_martin]

Re: A stupid question about planing?

If your load changes dramatically, and you're concerned about top speed, you need to swap props for different situations. I sense that you aren't concerned about WOT speed, so you could prop for maximum load, and just throttle back to prevent over-reving under light load conditions.

I have a lighter boat with about that power in an outboard, and I use different props for fishing (bass fishing, racing to fish) and camping/water skiing.

For overall brute force hole shot performance, if you buy a new prop, look into the high five.

hope it helps
John

 

[wahnamch]

Re: A stupid question about planing?

Wahn, take the switch on the back of the tach and turn it back and forth a few times, some of the time this will cure the problem, as corrosion will mess up the electrical contacts on the back of the tach. Just make sure it goes back in the same position it was.

H​

I didn't even know there was a switch :redface:. I'll check it out ASAP and get back to you. Thanks again for your continued help.

Andrew​

 

[hwsiii]

Re: A stupid question about planing?

You are very welcome Andrew, and i hope it works.

Oshkosh, yes that is the way it works. I have a form for you to fill out, and then I run my numbers for you.If you would like me to do this just start a new post of your own and I will post the form for you to fill out and give you the results.


H

 

[wahnamch]

Re: A stupid question about planing?

I can't find a switch on the tach :redface:. Does anyone have a photo to show me what to be looking for?​

 

[hwsiii]

Re: A stupid question about planing?

It might just be a hole in the plastic case that you have to insert a screwdriver in to turn it, but be careful and don;t short anything out. If you give us the make and model number we may can help more.


H

 

[wahnamch]

Re: A stupid question about planing?

Finally got back to this. I found the screw you mentioned. A couple of clicks back and forth and now I get stable rev readins. Thanks a bunch for that tip.

New measurements (only 3 adults in the boat this time):
2000 rpm = 14 km/h
2500 rpm = 20 km/h
3000 rpm = 37 km/h
3500 rpm = 46 km/h
3800 rpm (WOT) = 51 km/h

All speeds are GPS measurements.

Looking forward to hearing back from you.

Thanks again,
Andrew​

 

[hwsiii]

Re: A stupid question about planing?

Andrew, You are showing a prop slip of 16% at WOT and that is high in my opinion, and you are only showing a WOT of 3,800 RPM and if the correct RPM should be 4,800 RPM it appears to me we need to find out what is going on, because you should be getting more speed and RPM than you are now. We need to have the prop taken off and put the 17" prop on there if it is not bent or has problems. And rerun the tests and see what the make, model and pitch is of the prop that is on there now.

Thank you for the save QC.

Prop Slip

H

 

[QC]

Re: A stupid question about planing?

hwsii,

You did see Kilometers per hour?

 

[hwsiii]

Re: A stupid question about planing?

QC, my lord I am getting old and RETARDED.. LOL
I used KNOTS. I need to see the doctor evidently, two mistakes in two days.


H

 

[QC]

Re: A stupid question about planing?

Doh!!!! LOL

 

[hwsiii]

Re: A stupid question about planing?

QC, this is what I was looking at. LOL

IN MY DEFENSE LOL


H

 

[wahnamch]

Re: A stupid question about planing?

Thanks again. And sorry if I caused any confusion.

I'm not sure if the other prop we have will fit. As soon as I get hold of our mechanic, I'll ask him to take a look and see if we can swap the props.

Once/if we can do this, I'll report back again.

Your continued assistance is really much appreciated.​

 

[hwsiii]

Re: A stupid question about planing?

You are very welcome.


H