77 Evinrude 115 hp won't go faster than 20 mph

Faztbullet

Supreme Mariner
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Mar 2, 2008
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15,589
Post a picture side view of motor and transom....either the motor is mounted too high or a obstruction/tranducer/hook in bottom of boat is disturbing water flow. Also a pic of the prop.
 

Ktgritz

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Jul 22, 2017
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I've tried 3 different props a 13 + 3/4 x 15 a 14 x 17 and a 14 x 21 no change I would post a picture but it says I'm not authorized
 

interalian

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Jul 23, 2009
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Is the flat anti-ventilation plate on the motor (just above the prop) level with or slightly below the keel, or is it higher? And is this a new-to-you rig or a motor swap?
 

Ktgritz

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Jul 22, 2017
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Slightly below and no this is the factory engine for this boat from 77
 

Ktgritz

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Before I lowered it
 

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Faztbullet

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Going to bet that red painted diamond plate is disturbing water flow........
 

interalian

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No Title

Could you show us a picture from the rear with the anti-ventilation plate level in the middle? Like this attached.

And is the bottom of the hull smooth and uninterrupted as it ends at the transom?
 

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Ktgritz

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No Title

The diamond plate is flush on the bottom
 

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interalian

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Well, if the hull is smooth and flat up to the diamond plate, I don't see how it would be making the prop lose bite like in your video. And you moved the motor down (!). If anything, the motor needs to be moved UP until the plate just above the prop (that's your anti-ventilation plate) is inline with, or slightly above the extended line from the hull's bottom.
 

interalian

Commander
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In the shot I included on post #14 shows my motor up a tad. I had it lower and the AV plate would drag in the water. Have you weighed your boat lately?
 
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