Transom height and motor shaft length?

[RUGER]

Ok so when I am at full throttle water shoots up in the air at the back of the boat.
Buddy said I needed a long shaft motor.
I noticed the motor is mounted about an inch above the top of the transom?

I am thinking ''tis is a 20" shaft ?
End of the tape measure is at the bottom of the spot that is normally resting on the transom.

I was thinking about lowering the motor but from what I read the plate should be about flush with the bottom of the boat and this looks right to me ?

Height of the transom.

So is this setup right or no ?
Yamaha 25 hp


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[scn]

It looks right to me. You have another set of mounting holes that would drop it down a little. It might be worth a try to see if it will run better.

Or, there are some manual jack plates that aren't as expensive as the electric. It would set the motor back a few inches and give you a better hole shot. You would also have the ability to "play with" the mounting height through the jack plate adjustments to find the sweet spot for your motor.

I see nothing in your pictures that would make me think you needed a longer shaft motor.

 

[RUGER]

Thank you sir.
I wasn't positive but I didn't either.

I think the biggest issue I have is I am a little under powered for my boat.
Honestly though, it gets from point A to B and back so that is about all I need.

 

[catman529]

Mine used to shoot water up and even over the transom at full throttle when the motor was too low. I rebuilt the transom and made it 4" higher so the bottom plate is about flush with the boat. Rides a lot better now. So I guess I had the opposite problem that you do. Although I don't think your motor looks too high. I could be wrong but it looks on the low side to me?


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[RUGER]

Now that I think about it I moved the tilt down a hole from where it was from the factory.
I was trying to get it up on plane with a couple people in the boat.

Would moving it back up do anything?

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[woodyard]

If I remember correctly in doing some research , the cavitation plate should be running within about an inch of the bottom of the boat. Yours looks about right. The tilt might make a difference. I know on the ark boat it has a sweet spot that will spray lot less water when we are running wide open.

 

[Big Ben]

Most motors are set in the second hole from the stern, looks like yours is in the first hole. I would change that and see what the results will be. Mine was in the 4th hole when I got it and I moved it some but still wouldn't plane the boat like I wanted. Moved it to hole #2 and put the small hydrofoil on and can't be any better IMO. For a old 18hp it will make that 1448 scoot. Also I never seen one mounted a inch higher than the transom like that, if I could I would lower it down flush.
edit..I had water flying higher than the transom but turn out to be the angle of the fish locator sensor that is mounted right at the waterline stern. Angle it up against the bottom of the boat looking foward and problem solved. Now shoots a small roostertail up and away.

 

[Duck dogn]

I run mine flush will the bottom of boat, someone notched my transom and set my motor lower. With that being said it sprayed water and I couldn't hardly run the duck river. If it where mine I'd raise the cavitation plate which I circled up to the line I drew. I made a Jack plate and min could stand to be raised another notch , just make sure when at full throttle it's still peeing and not starving for water

 

[Duck dogn]

not sure how to rotate the pic

 

[Kevin]

Ruger your cav plate is WAYYY low.

That is why you're getting spray.

As stated above, you're cav plate should be about flush with the bottom of the transom.

When you are running at WOT, you're cavitation plate should be visible, and running above the water line for most optimal engine performance and efficiency.

 

[RUGER]

Hmmm, maybe that's why they raised it up an inch when they mounted it.

 

[Andy S.]

These may help you RUGER:

 

[RUGER]

Yeah I looked at those to see where to measure from and to when I posted these pictures.
It's almost like my boat is right on the edge of needing either a short or long either one.

I'm gonna tilt it back up one hole and go from there. Best I remember I didn't get the spray till after I lowered it.

 

[Big Ben]

Sure fixed the roostertail that came up and hit the transom when I adjusted the sending unit on the locator on mine. Pointed the forward end upwards against the bottom of the boat. Was out yesterday and now it throws a roostertail about 2 foot high still but comes up 3 or 4 foot off the stern. No water hitting the back of the boat.