Height outboard or modify propeller

**OnPad** · 01-16-2022, 11:21 AM

I agree with rock and Jimboat. It looks like your setup is good. I even think you rpm is about right. If you want to drop your rpm you can add a little cup to the trailing edge of prop or go up 1" pitch on propeller.

**Dave Strong** · 01-16-2022, 12:50 PM

As Jim said you are close to the optimum for your set up, at this point you need to fine tune with trying different engine heights and may need to get a different prop.

Dave

**MrG** · 01-16-2022, 03:28 PM

In South Florida back in the 80 we use a Dixie cup from water cooler or snow cone cut a V in it and fill it with marine TX epoxy and shape it like a mercury cle case ..= 5 MPH increase also caked a bond nose cone FYI

**wettek** · 01-16-2022, 05:48 PM

I wouldn't increase the pitch on the prop. 5600 is pretty much perfect for that engine. At 5200, you will be overloading it and risk damage.

**Marco128** · 01-16-2022, 06:19 PM

Are you talking about a handcrafted nose cone without seacock? I've heard below 75 mph slow down

**Dave Strong** · 01-16-2022, 06:22 PM

Originally Posted by Marco128

Are you talking about a handcrafted nose cone without seacock? I've heard below 75 mph slow down

They do more so if you need positive trim to get best speed.

Dave

**MrG** · 01-16-2022, 06:24 PM

Not a big cone just small one omc cases are not streamlined like Yamaha and mercury they are thick at the leading

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**Marco128** · 01-16-2022, 06:27 PM

I understand, I have a neutral trim at top speed, I don't need a positive trim

**Marco128** · 01-16-2022, 06:29 PM

Originally Posted by MrG

Not a big cone just small one omc cases are not streamlined like Yamaha and mercury they are thick at the leading

This is a nice project

**MrG** · 01-16-2022, 06:34 PM

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Most low water pickups are surfing the case but 4 below Bottem this little time working gave 4 mph

**Marco128** · 01-16-2022, 06:53 PM

Originally Posted by wettek

I wouldn't increase the pitch on the prop. 5600 is pretty much perfect for that engine. At 5200, you will be overloading it and risk damage.

You say?? Even if Da booklet should it do 5200 rpm?

**Marco128** · 01-16-2022, 06:56 PM

Originally Posted by MrG

Most low water pickups are surfing the case but 4 below Bottem this little time working gave 4 mph

Great, then I'll get to work right away and I'll do it the same

**wettek** · 01-16-2022, 07:01 PM

Yes. 5200 is minimum. 5600 is pretty much perfect for that engine.

**rgsauger** · 01-18-2022, 12:18 AM

Would it be easty to space your motor away from the boat about 3”-4” and see how she did? You might be able to go back and up and get better overall performance.

**Marco128** · 01-18-2022, 08:05 AM

Now I have a fixed lift of 3 inches, they are a bit small, I never tried to put an additional thickness, I wanted to add a rigid pvc plate of 1.5 inches, as you said:Concordo: