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Old 13 January 2011, 05:43   #1
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how do I know what size my prop is?

dumb newb question if ever there was one.....

I want to try a different prop on my RIB. It's on a Mariner 60 ELPT EFI 2002.

How do I know what 'size'/pitch etc the existing one is? I imagine it's like tyre sizes - easy when you know how!!

Also, what does WOT stand for?

Cheers

Richard
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Old 13 January 2011, 06:02   #2
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WOT is 'wide open throttle'. i.e. full revs

Prop size is normally stamped on the side of the prop e.g. 14 x 12 which would mean 14" diameter and 12" pitch. If it doesn't say it somewhere then there is probably a part number instead which would give you the size off the manufacturer's tables.
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Old 13 January 2011, 06:25   #3
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excellent, thanks very much
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Old 13 January 2011, 06:41   #4
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Some Merc props might just have a part number stamped on, in which case just google the number.
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Old 13 January 2011, 08:39   #5
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If it's a genuine Merc/Quicksilver prop, the part number will be stamped on the mating surface of the prop, where it meets the thrust washer.

I've got a couple of props here to suit your motor. Let me know what pitch you're looking for and I may be able to help you out.
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Old 16 January 2011, 08:03   #6
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Thanks downhill dai.

That's the problem, I'm all a bit new to this and don't know what I don't know!

The only number I can see on the prop is 23, by the thrust washer.

I'm now trying to work out whether to go smaller diameter or shallower pitch. What difference does each make to the overall performance?

To reiterate, I want to get on the plane easier when fully loaded. If I get 25 knots top whack I'd be pretty happy.

Sorry to sund like a dumba*s - it's just that on this topic I am!
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Old 16 January 2011, 09:50   #7
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What's your current top speed? And maximum rpm currently achieved?
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Old 16 January 2011, 10:58   #8
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He'll still need to find out the pitch on his current prop, to decide how much to increase or decrease it depending on rpm etc.

There must be some other numbers stamped on it somewhere. Have you checked both ends of the hub Portholme. Make sure the thrust washer is corroded onto the hub covering the numbers.
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Old 16 January 2011, 12:54   #9
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matt h has a similar size Zodiac with the same motor and he uses a 15" pitch prop - his 14" was too fine. I've got a 15" pitch genuine Merc prop here, if you're interested.
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Old 16 January 2011, 14:46   #10
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Downhilldai

I'm interested but I guess it depends what you are after for the prop.

you want a PM me?

Cheers

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