AR192 Caviation

[Matt Appler]

I have a small issue with my 2013 AR192. I believe this is what is described here as "cavitation", but I am not certain. The last two times I have taken out my boat, at the beginning of the cruise (first couple of minutes) at SLOW speed, the boat feels like it does when you leave the intake cleanout port plug out, and there is drastically reduced propulsion. The boat rattles a bit, although the engine itself sounds fine. Pee holes are flowing normally. Waiting, or perhaps throttling up slightly seems to resolve it, and it did not come back again. Both times, I opened the cleanout port and found no debris. It almost feels like the boat "slips" into gear and gets moving (I know there is no gear, that is just what it feels like). I have two questions:

1) Is this what is meant by "cavitation"?
2) Assuming it is, is there any harm in continuing to operate the boat? As I said, it seems to "snap" back into operation and runs normally after this issue.

I have read the many posts on cavitation and the will be inspecting the impeller, housing, intake, etc. next time I am on the boat.

Thank you,
-Matt

 

[swatski]

I have a small issue with my 2013 AR192. I believe this is what is described here as "cavitation", but I am not certain. The last two times I have taken out my boat, at the beginning of the cruise (first couple of minutes) at SLOW speed, the boat feels like it does when you leave the intake cleanout port plug out, and there is drastically reduced propulsion. The boat rattles a bit, although the engine itself sounds fine. Pee holes are flowing normally. Waiting, or perhaps throttling up slightly seems to resolve it, and it did not come back again. Both times, I opened the cleanout port and found no debris. It almost feels like the boat "slips" into gear and gets moving (I know there is no gear, that is just what it feels like). I have two questions:

1) Is this what is meant by "cavitation"?
2) Assuming it is, is there any harm in continuing to operate the boat? As I said, it seems to "snap" back into operation and runs normally after this issue.

I have read the many posts on cavitation and the will be inspecting the impeller, housing, intake, etc. next time I am on the boat.

Thank you,
-Matt

I'm going to guess that you are fine! Define "SLOW", please. Keep in mind not much happens before you hit 5,000+ RPM to get up and going - it can be very confusing if coming from traditional boats wherein you would be redlining!

Cavitation is a silly term, it really is technically ventilation, but the term we use describes impeller slippage - basically air ingress on the intake side of the pump/drive will cause impeller to spin up - similar to wheels spinnig in mud wiht no traction.

Cavitation can be very bad and eat away SS and damage the impeller and wear ring. But I don't think you really have that. Best test - hit the WOT from a dead stop - you should be able to gain thrust relatively quickly.

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[Matt Appler]

Thank you, "impeller slippage" or "ventilation" as you describe it does seem to be what I have felt. "SLOW" in this context is at No Wake and then slowly throttling up from there, to a throttle setting I would assume was going to be 6-8 knots. Hitting WOT seemed to clear the issue immediately. "spinning in mud with no traction" is a great description.

Just to be clear as well, I've owned the boat from new, and this is something I haven't experienced before. I've got 150-180+ hours in the boat so far.

Thank you very much for your response.
-Matt

 

[Scottintexas]

Congratulations on the use of your boat!

Are both engines affected? maybe leave idling and in neutral and power up with the other to see if you can isolate the issue,

Cavitation can also manifest itself in several different ways which makes it even more difficult, is it your impeller, is air intrusion, is it an obstruction ??

my loose silicone/air intrusion cavitation manifested it self while increasing speed from and made the boat vibrate and shake like it was going to come apart, sometimes I could gently nurse it through this zone and get up to full RPM and the symptoms went away,

I would lean towards maybe you have something stuck on the impeller shaft that's causing a disturbance (like a walmart or ice bag or rope) and then once at higher speeds it doesn't affect it anymore or maybe you have loose silicone allowing air in up to a certain suction rate,

it's time to get it off the water and take the impeller shaft out and climb underneath and look up into the intake grates,

 

[Scottintexas]

sorry just realized you only have one engine

it won't hurt to operate the boat with this condition but if I were you it would be on my list to figure out sooner rather than later as it's an inconvenience that might be easily fixed,

 

[swatski]

What @Scottintexas said.
But given your symptoms are a bit unusual, I would also check the reverse gate operation, to make sure it is not hanging too low at the first and second throttle lever "indent".

If you can get your boat on the trailer, inspecting the impellers and the tunnel can be done by sticking a cell phone/camera up the intakes (from under the boat), and I have had on occasion debris stuck between the impellers and the stator segment of the pump - need to pull the pump/steering/venturi nozzle to clear that up. If it is some twigs that are not hard - it could explain your findings - just look from behind the boat through the nozzles.

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[swatski]

@Matt Appler The last time I had to pull the pump - two weeks ago - I had this stuck in the impeller. The largest piece was about 1-2"-sized.

Symptoms from the above were not like yours, but what you are describing reminded me of the other time I had something stuck up like this - below
I remember now - those twigs were giving me weird feedback at low speed but once I opened up the throttles - seemed to run okay.

That above is the stator segment - directly aft to the impeller.

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[Moose]

I have had the same problem. Its almost like the impeller is slipping on the shaft and then catches. It has occurred at low enough engine rpms that I do not think it is cavitation. It also did not show up until 60 plus hours. Next time it happens I intended to.stop the engine before it clears and inspect the impeller and intake.

 

[Jgriffy]

have you have this issue anymore? I purchased mine in 2014 brand new and for the 1st time am having this issue, started with an overheat fault, I have taken it all apart and there is no debris stuck in the screw, but feels like if there was a clutch it would be slipping if you know what I mean.
And does anyone know where to access the thermostat on this boat?

 

[Matt Appler]

Yeah, I sure do. I haven't put my boat in the water yet this year (but it will be in soon). I was having it happen pretty regularly last year.
I should note, I ONLY had it happen during initial operation on putting the boat in. I keep my boat on a boat lift, and so drop it in the water, use no wake speed to pull away from my dock, and then no wake speed to leave the no-wake zone near the shore. Then, when I get out into the lake, I open up the throttle.
If I am out getting gas (at a marina dock), turn the engine off a while, and restart, I have never had this issue happen. I am curious if dropping it in from the lift is finding a way to keep an air bubble in there somehow? Maybe some debris that isn't clearing until I throttle up? I'm not sure really.