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Old 25 January 2013, 09:30   #1
Country: UK - England
Town: Hoxne
Boat name: Southern Comfort
Make: NorthCraft 5.5
Length: 5m +
Engine: 150 Optimax
MMSI: 235033276
Join Date: Nov 2005
Posts: 122
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New Prop's got Casting marks and holes

Has anyone ever seen this?

New prop arrived today from Mercury, externally looks immaculate, but on the inside there are obvious casting marks, fissures and even a hole.

I've been assured that this is normal and " how they come from the foundry" as it is just how they are cast, but some second opinions would be nice.

Anyone seen anything similar on any of their merc props?
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Old 25 January 2013, 09:47   #2
Country: UK - England
Town: Hamble
Length: 9m +
Join Date: Dec 2002
Posts: 2,256
I've had a few like that from Mercury (barrus) and although they don't look to good, they've never let me down. The worst one is on a 635hp sterndrive motor, and it's fine.

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Old 25 January 2013, 12:42   #3
Country: UK - England
Town: bicester
Length: no boat
Engine: outboard only
Join Date: Feb 2009
Posts: 853
there should be four holes around the prop hub that is to allow the exhaust gases to escape, if you dont have the four holes then the obm will not run, it will stop after a few seconds, the holes used to be oblong in shape,if you havent got the holes dont fit it send it back, I have only seen one prop with all the holes blocked in seventeen years working on obms
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Old 25 January 2013, 12:48   #4
Join Date: Dec 2012
Posts: 35
I wouldn't accept it. The blow holes as I'd call them in the casting, to me, suggest uneven metal strength. If it was me and i was in no rush for the prop I'd send it back. Had bad experiences of poor casting on agricultural machinery, not quite the same as a prop, i know!
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Old 25 January 2013, 14:10   #5
Country: Poland
Town: Gdynia
Boat name: Baltic Quest
Make: Parker 900 Baltic
Length: 9m +
Engine: Inboard, diesel
Join Date: Sep 2010
Posts: 27
In par Bravo one I've got exacly this same casting mistakes and during two heavy commercial use no problem at all. Live it as it is.

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Old 25 January 2013, 18:47   #6
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Country: UK - England
Town: London
Make: Ribcrafts
Length: 5m +
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Did you send them pictures of the holes??

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Old 31 January 2013, 16:57   #7
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Country: UK - England
Town: slough
Boat name: not named yet
Make: Orkney Dory 4 metre
Length: 4m +
Engine: outboard evinrude 60
Join Date: Sep 2009
Posts: 80
Dont use the prop send it back with a letter of complaint.
you are right in that it is weak and is a bad/poor casting.
Its ok for some to say "mine is like that and its been ok, but at anytime the prop could break away from the hub and fly off in any direction at great speed
The bad casting that is showing might be even worse if the paint is taken off the prop.
Bad /weak casting is a dangerous sign and one that mercury themself are often complaining about with cheap inferior props.
Mercury will not mind one bit you sending it back, and any boat shop that says this is ok should be avoided like the plague.
Ther propeller is a major component and the manufacturer only knows of a bad batch when people complain.
This one obviously was missed by quality control.
The prop is very porous, and that is one thing you do not mess around with on a shaft that will be spinning in excess of 2,000rpm and under great pressure on the blades.

get intouch with supplier and let them know your sending the prop back and will be expecting a replacement and for them to re-imbure postage of the defective prop.

dont let them tak you out of it as this prop is NOT FIT FOR PURPOSE.


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