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Old 18 May 2010, 16:49   #11
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Quote:
Originally Posted by jwalker View Post
The vent holes allow exhaust gasses to aerate the water in the vicinity of the prop at low speed so the engine has less load to drive, its revs therefore increase so provides more power to drive the high pitch prop.
Correct .. on Mercury props its called the PVS system, and as you say allows the prop to spin more freely at lower revs until it bites and when it does, and the boats on the plane, water pressure seals in the gasses which then vent normally through the arse end of the prop .. sorry.. was that a minor colloquialism?

With their system you can actually vary the size of the holes and so help the prop grab faster and tailor it to the load of your hull and no I'm not a merc salesman cos heres the science .. no fooker ever does adjust the size of the vent holes .. however.... this is ribnet, and I await correction
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Old 19 May 2010, 03:56   #12
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You may find that the cupped prop will give more bow lift (if you're being picky it's actually less stern lift), but they will certainly behave differently and one will probably suit your hull better than the other.
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Originally Posted by Zippy
When a boat looks that good who needs tubes!!!
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Old 19 May 2010, 11:38   #13
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Originally Posted by Bigmuz7 View Post
With their system you can actually vary the size of the holes and so help the prop grab faster and tailor it to the load of your hull .. no fooker ever does adjust the size of the vent holes .. however.... this is ribnet, and I await correction
I think those props come with little push-in plastic plugs to adjust venting. These plugs usually end up in the garbage with the rest of the propellers packaging as soon as the prop is removed from the box.


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