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Old 11-05-2007, 06:27 PM   #1
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cavitating

my p23 with 225promax cavitates like mad when you give it some wellie, at any speed, its on a stainless steel leg running a four blade?

my dad said he found on here, sommin about different legs can do that?

any advise?? because it nearly cought us out in the chop last week, it was really rough tried to get back in over the chop it was just cavitating flat out and bogging down? but when she bites she does really shift?

any ideas

thanks
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Old 11-05-2007, 06:34 PM   #2
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Lewis aint cavatation when the engine is over revving/slipping not bogging out?
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Old 11-05-2007, 06:38 PM   #3
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yeah it might have just been the conditions on sunday made it feel like bogging out, but we get loads of revs and not much action? just curious, is it proped wrong?
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Old 11-05-2007, 06:50 PM   #4
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Maybe? When its flat what are the revs like? Got a jack plate? Engine to high?
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Old 11-05-2007, 07:15 PM   #5
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Speak to cronky mate he knows his stuff.
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Old 11-05-2007, 09:19 PM   #6
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What height is the engine? could you get a pic of the engine trimmed level with a peice of wood or something flat coming off the bottom of the v to the gearbox.
what prop do you have?
an offshore leg influences the prop to slip less as insted of all the exhaust going via the prop allowing it to spin up, the exhaust is released via the open exhaust
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Old 12-05-2007, 09:26 AM   #7
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Cavitation is when the water 'boils' on the surface of the prop blades, meaning the prop doesn't bite/grip properly. It's usually caused by damage on the surface/edges of the prop blades & can be diagnosed by the fine pitting on the blade surface caused by the 'boiling' water.

Ventilation is when air is sucked down from the surface onto the prop, again causing it to slip. This is usually due to the engine being too high or trimmed out too far. Generally the anti-ventilation plate above the prop should be level with the bottom of the transom but higher performance boats like yours usually have it set slightly higher for less drag & more speed.
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Old 12-05-2007, 09:53 AM   #8
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thanks for getting back to me, it does it slightly when trimmed in aswell, i heard it does it to build revs, apparently the prop on it is for higher top end rather than accel
and she does have a nice rooster!!
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Old 12-05-2007, 09:59 AM   #9
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I'd have thought you would want to be trimmed right in when rough anyway
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Old 12-05-2007, 11:45 AM   #10
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oh yea i knw, im was just saying in perfect conditions having the boat trimmed just right, she gives a nive rooster. which i dont knw why i really like

is it worth trying another prop? also she wont rev past 6,000-6,200 rpm, isnt it supposed to rev to 6,700??
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Old 12-05-2007, 11:58 AM   #11
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What prop do you have at the momeny?
all the props, engine heights etc have still slipped abit just something you have to put up with, after all it only slips for around 3 seconds then throws you back in your seat
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Old 12-05-2007, 12:27 PM   #12
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its currently on a four blade, unsure of pitch.

it slips for longer than three secs! also my old xr2 on ring 20 never used to, well not tht much anyway,
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Old 12-05-2007, 12:29 PM   #13
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are you trimmed right in when its slipping?
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Old 12-05-2007, 02:41 PM   #14
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yeah, it happens at all angles of tilt!
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Old 12-05-2007, 03:20 PM   #15
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Is the prop damaged at all?
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Old 12-05-2007, 07:09 PM   #16
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As this happens in all trim conditions it may be that the hub is slipping.
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Old 12-05-2007, 07:13 PM   #17
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Quote:
Originally Posted by MrRob View Post
As this happens in all trim conditions it may be that the hub is slipping.
How can the hub slip?
If the hub was broke he would have no drive or no prop
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Old 12-05-2007, 07:16 PM   #18
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Quote:
Originally Posted by PuppiesBalls View Post
How can the hub slip?
If the hub was broke he would have no drive or no prop
As the hub of the prop gets old and worn they can slip. I had to have my old Laser II rehubbed when I 1st had it as it slipped like a bastard.
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Old 12-05-2007, 07:38 PM   #19
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Ahh i understand
I just had the image of the Flowtorque hub in my mind and couldn't see how it could slut
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Old 12-05-2007, 08:36 PM   #20
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Quote:
Originally Posted by TheOrs View Post
Cavitation is when the water 'boils' on the surface of the prop blades, meaning the prop doesn't bite/grip properly. It's usually caused by damage on the surface/edges of the prop blades & can be diagnosed by the fine pitting on the blade surface caused by the 'boiling' water.

Ventilation is when air is sucked down from the surface onto the prop, again causing it to slip. This is usually due to the engine being too high or trimmed out too far. Generally the anti-ventilation plate above the prop should be level with the bottom of the transom but higher performance boats like yours usually have it set slightly higher for less drag & more speed.
YES Great somebody else has this correct.
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