Motor feels like it's cavitating.

[23ParkerWA]

I have a 1991 2310 Walkaround with a 1997 Johnson 225hp sitting on a stainless marine motor bracket.

The motor is as far down as it'll go.

When I'm running trimmed out the wash is almost like a small rooster tail.

The water comes up just to the bottom of the cowling.

When I turn sharp the motor cavitates. When I floor it from 3k to 4k it cavitates. I added a cavitation tail to it and it helps plane a little better maybe but it still cavitates.

Motor maxes out at 4500rpm at about 30mph.

No trim tabs on boat.

It just doesn't feel right and I would like to hear from some guys who ran into this. Thanks

 

[warthog5]

When I'm running trimmed out the wash is almost like a small rooster tail.

I'm sure it is cavating.....Your trimmed to high.

Especially in a higher speed turn.

 

[markman03]

Trim your motor down in a turn. If you are shooting a rooster tail you are to high.

 

[johnkn]

And after the above (assuming your motor is mechanically sound) and you're still only turning 4500 RPM, you need to re-prop to get the RPMs up into the recommended range.

My 2510 MV Walk-around would do 40+ MPH with a single 225.

 

[23ParkerWA]

It shoots a 2' rooster even with motor tilted all the way down.

I'm wondering if I need a 30" shaft on this boat

 

[shawnee83]

How long have you had your boat? Has it always been this way? I'm not familiar with the 91 2310 but I thought initially that they were a notched transom? Where does the AV plate on the motor line up with the keel when the motor is trimmed all the way down? Do you have any transducers or live well pick ups mounted on the transom and if so where? Also, it would be helpful to all if you could take some photos of your stern (boat out of the water) with the motor down so we can see your set up. I agree, your WOT RPM's are to low. Lots of questions I know.

 

[23ParkerWA]

I just bought this boat a few weeks ago. I've used it about 4 times so far.

I thought I looked at the cavitation plate to see how it lined up to the keel but maybe I was distracted. I don't have a pic with the motor down but if you look at where the motor would sit, it's like it is just above the keel.

I'll get some better pics on Wednesday

 

[shawnee83]

I'm sure it's just the angle of the photo but it looks like the end of your AV plate is bent down? It's probably the trim? Post some pics of it down when you can.

 

[warthog5]

I thought I looked at the cavitation plate to see how it lined up to the keel

You have a bracketed boat.....This does not apply....On a boat with the motor directly on the transom it should be there or 1in above.

Are you sure you have a 25in shaft motor.....and not a 20in shaft?

 

[got_em_on]

Could be the wrong prop or maybe the prop needs to be tuned a little.

 

[Megabyte]

Are you sure you have a 25in shaft motor.....and not a 20in shaft?

Here is a 20" shaft Ocean Pro.

 

[shawnee83]

I believe that on a bracket, the AV plate should be a little above the keel line? Maybe 1" or so. I think that is what Warthog is saying also?

 

[shawnee83]

Are you sure you have a 25in shaft motor.....and not a 20in shaft?

Here is a 20" shaft Ocean Pro.

That Duffy you had Kevin was as pristine as the Megabyte. Whoever purchased that from one you hit the jack pot.

 

[Megabyte]

That Dusky you had Kevin was as pristine as the Megabyte. Whoever purchased that from one you hit the jack pot.

Thanks, tho that Dusky was actually the original Megabyte.
It was purchased from me by my SeaSchool instructor when I bought my 2520.

 

[johnkn]

Looks to me like the motor shaft is too short for that boat.

 

[shawnee83]

Starting to wonder if that is actually a 20" shaft. That would certainly cause these issues. A photo of where it is riding in relation to the keel should clear it up either way.

 

[23ParkerWA]

Funny you guys mention the shaft length. I was assuming it's 25" and possibly needing a 30". But it being a 20" could be possible. I will take better pics later this week when I head back down to the Cape.

 

[23ParkerWA]

After looking at pics of 20" shafts I'd say mine is definitely 25"

http://www.ebay.com/itm/1995-Johnso...rd-Motor-Boat-Engine-20-200-150-/221815749253

 

[shawnee83]

After looking at pics of 20" shafts I'd say mine is definitely 25"

http://www.ebay.com/itm/1995-Johnso...rd-Motor-Boat-Engine-20-200-150-/221815749253

That does look shorter than yours

 

[warthog5]

Get the serial number off the motor......Call your local Johnny/Rude dealer with that number and ask what the shaft length is.


EDIT: Look it up right here - http://evinrude-parts.com/evinrude_model_number.html