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Old 22 December 2015, 05:13   #1
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E-TEC prop.........

Hi all

I have a 21" Viper prop on my E-TEC 150 (Vipermax 5.8).

It has a bit of minor damage here and there which has been sanded out carefully (just very minor nicks in the leading edge - mainly from picking up small stones when launching).

I have noticed over time that it is getting more prone to break out and cavitate when you accelerate hard with the helm well over - even when it's trimmed well in.

Would a 4 blade prop help with this - and what would be a good (safe) option? Due to location, trying different props is not an option so it would be a one time purchase.
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Old 22 December 2015, 05:27   #2
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hi mate not an expert but something has changed if you were propped properly in the first place. i would talk to someone like steel developments Home page tel 02088747059 fax 02088779537.

hope that helps

cheers
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Old 22 December 2015, 05:52   #3
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Hi Stephen, what are your RPMs at WOT and speed ?
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Old 22 December 2015, 06:10   #4
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Hi Stephen.

I've probably got the most similar set-up to you, Vipermax 6.2 (Out of the same mould as yours) and a 150 Evinrude DI. Now you have to bear in mind my RIB is heavier than yours and my gearbox ratio might be slightly different to yours but I've been running a standard Viper 19p prop most of the time I've been running my RIB. It did come with a 21p viper but it wasn't getting up to the recommended WOT revs.

Once set-up I've never had breakout or cavitation/ventilation on hard cornering and my prop has had similar small chip damage as you are describing. I've recently tried a 17p Viper and with impressive holeshot and only down on max speed by a couple of knots. Again handling is superb but fuel consumption is significantly higher.

IMO I reckon that you were on the edge of what you could get away with on the engine height. A bit of damage on the leading edge of the prop could be enough to drag air down when on the limit and cause ventilation during hard cornering. If you are confident that your prop is okay I would be lowering your engine height by a bit and see if that sorts your problem. If you are after another prop I would be looking at possibly going down to a 19" (depending where your WOT is now), if that doesn't quite do the trick in the high performance stakes, you'll have a rough water prop and also a useful spare too.
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Old 22 December 2015, 07:00   #5
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Was the prop good when it was new?

If it was then the prop is damaged in a way that's degraded its performance - perhaps it's out of balance or a blade is slightly bent - which you might not see.

If the prop was good when new then you need to either get that one refurbished or simply buy the same again - I appreciate that distance might be an issue for you!
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Old 22 December 2015, 11:30   #6
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Old 22 December 2015, 11:40   #7
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Old 22 December 2015, 13:02   #8
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Pardon.

Ah now! Are you being subtle or ironic?😄
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Old 22 December 2015, 13:22   #9
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Ah now! Are you being subtle or ironic?😄
No dave just obstructive as usual, obviously on the holiday juice tonight
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Old 22 December 2015, 13:44   #10
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