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Cavitation problems

Old 01-22-2003, 04:53 PM
  #1  
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Default Cavitation problems

THOM/OTHERS
I HAVE A 23 SEACRAFT WITH A 582-L AND A B-45 AIRMAR DEPTH/TEMP BRONZE
THROUGH HULL W/BLUE FAIRING BLOCK. ITS MOUNTED ABOUT 10-12"
OFF THE CENTERLINE OF BOAT AND ABOUT 3 FEET FROM THE STERN. I'M GETTING
SOME PROP SLIPPAGE AND FEELS LIKE IT CATCHES IN GEAR AT CRUISING SPEED
30 MPH. I DROPED THE ENGINE 1 NOTCH AND THIS DIDNT HELP. I CAN'T GO ANY
FURTHER OUT FROM THE CENTERLINE, MAYBE 1.5 " IF I'M LUCKY. SO I'M THINKING
ABOUT A TRANSOM MOUNT INSTEAD. DO YOU THINK THE TRANSDUCER IS CAUSING
THE PROP TO CAVITATE AT LOW SPEEDS? I AM
USING A 15 1/4 X 17 PROP IN GOOD CONDITION.
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Old 01-25-2003, 06:16 PM
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Default Cavitation problems

I don't think it could be the problem,but in looking towards the bow what is in front of the thurhull transdurcers? Is there any lifting strakes that end in front them that could funnel a bubble stream back towards the thurhulls and hit the thurhulls insuch a manner that it funnels the bubble stream in more towards the center line of the hull.And that's what feeding air to the prop?
To try a experiment ,you could get a piece of plastic rod stock larger than the diameter of the thur hull.And have a machine shop,oval head and turn down and thread the stock to match the nuts from the present thur hull.Install the mushroom head in place of the tranducers and test the hull in the water. Should answer the question quickly.
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Old 01-25-2003, 09:46 PM
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Default Cavitation problems

Try a 4 blade 16p prop.

Scout 202 SF Yamaha F200
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Old 01-26-2003, 04:48 AM
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Default Cavitation problems

seafari...quote:I'M GETTING
SOME PROP SLIPPAGE AND FEELS LIKE IT CATCHES IN GEAR AT CRUISING SPEED
Have you checked to see if your prop is slipping on the hub? Mark the hub and the prop with a magic marker...take it for a ride and see if one mark moves Vs the other. Just a thought.

"Never enough time to do it right; ALWAYS enough time to do it over." Boston Whaler, "MUMBLER", 24' Outrage (1996), twin 175 HP Evinrude Ocean Pros.
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Old 01-26-2003, 06:03 AM
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Default Cavitation problems

No, I do not think your transducer is causing a disturbance in the water flow that is then causing ventilation at your prop. That doesn't mean for a second that I know what is causing the problem though.

The simplest of questions is this, do you know how was it acting before you put the transducer in there or is this an installation into a new boat with no earlier performance to compare how its acting now to?

Thom

"For every complex question, there's a simple answer. And it's wrong."
(--H. L. Mencken)
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Old 01-27-2003, 04:34 PM
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Default Cavitation problems

Seafari, for what its worth I had the same problem. After installing our transducer our port side engine would cavitate. It took us a little while to figure out that it would only cavitate in 3ft. seas. We took the boat out of the water and turned the transducer so that it lined up perfectly with the bow. This seemed to help but it did not fix it. Out the boat comes again take the !@#$% transducer off and put a fitting in for a wash down. Mount the transducer in the hull and a transom mount for temp. GOOD LUCK!!!!!

ps. If your motor cavitates it is starving for water.
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Old 01-27-2003, 05:52 PM
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Default Cavitation problems

I have a bracket mounted 225 on a old formula and I put a transom mount ducer right on the keel 29" in front of the engine right in line with it. Ducer was only digging about 1/4" deep. I thought with the engine that far back there would be no way the transducer would disturb the water enought to make the engine cavitate. Well it did at all planning speeds. I moved it over 18" and the prop was hooked up like magic. Answer is yes I think it can cause cavitation. Some thru hulls are set really deep and can mess up a lot of water. Thats why the read so good.



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