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Foamy wake, possible cavitation

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billythegrape

Contributing Member
1973 Johnson 50hp. On a 25' pontoon boat. I have a pontoon prop on it. My problem is that it seems like the motor is not deep enough in the water. Sometimes it bites nice, then it won't and the rpm will increase, then it will and the rpm decreases and it bites nice again. This happens most pronouncedly when turning sharply, going through someone's wake, or when everyone decides the front is the best place in the boat to sit.

Would one of those whale tails help this issue? I have the motor trimmed level to the boat; I have had it looking like a puppy with the tail tucked between its legs and it didn't seem to make much of a difference. Motor is also as low as it can go on the transom. It goes along fine, I just get worried it is screwing something up.
 
Only 2 things I can think of that would cause this. Engine is either too high on the transom, or the prop is possibly damaged and needs to be taken to a prop shop for repair/replacement.
 
You said it yourself----pontoon boat. The 'toons are digging a hole in the water ahead of the motor/prop when you turn. You gotta live with it. And don't drive like it is a high performance go-faster boat.
 
Hard to say without seeing it. Unless this engine has performed properly on the same rig in the past... Perhaps it is a case of having a certain length shaft engine installed whereas a longer shaft engine is required.
 
  • Only 2 things I can think of that would cause this. Engine is either too high on the transom, or the prop is possibly damaged and needs to be taken to a prop shop for repair/replacement.

    Engine is as low as it will go on the transom. Prop is almost brand new and is certainly not damaged in the slightest.

    You said it yourself----pontoon boat. The 'toons are digging a hole in the water ahead of the motor/prop when you turn. You gotta live with it. And don't drive like it is a high performance go-faster boat.

    Ok, so this is normal for a pontoon boat then? I have never owned one before this, and the engine has always done this. And ya, I don't expect it to go fast, nor do I need it to. I love its stately pace. I never run the throttle above 3/4- I even marked the lever/control box with a sharpie so my wife won't exceed it, hahah.

    Hard to say without seeing it. Unless this engine has performed properly on the same rig in the past... Perhaps it is a case of having a certain length shaft engine installed whereas a longer shaft engine is required.


    No idea- it has always done this, I was just worried I was hurting it somehow.
    ​
 
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