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Old 27 December 2005, 18:33   #1
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Anyone used one of these props before?

http://www.magicmarine.co.uk/props/index.html

Opinions? I decided against the variable pitch plastic prop-these replaceable blades seem a good idea though. I'm wondering about the performance of the props though with reduced backpressure (smaller hub) on a 2-stroke.
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Old 27 December 2005, 18:52   #2
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Am I missing somethhing... you seem to have linked to a fairly conventional prop
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Old 27 December 2005, 18:52   #3
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Not used this specific brand myself nor have heard of the before, this technique is not new and is used by Mercury on their larger props also Michican Wheel.
We sell both those mentioned brand and very good to be able keeping larger stock of props by offering centres for various outboard/sterndrive brands.

By they SOLAS have also brought their version out.

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Old 27 December 2005, 19:32   #4
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Quote:
Originally Posted by Richard B
Am I missing somethhing... you seem to have linked to a fairly conventional prop
yeah it is fairly conventional-but what I'm wondering is about the performance difference with a smaller hub-ie less backpressure. On a 2-stroke engine correct backpressure/pressure wave generation is critical to performance-but I'm not sure whether marine 2-strokes have got any further than "UG...more cylinders and more CC makes more HP". From what I've seen they lack the finesse of exhaust tuning-but maybe it works a different way and if so will having the smaller hub affect the power output and risk melting stuff?

If you lose backpressure on a 2-stroke bike exhaust it melts pistons, runs hotter and performance is severely affected-see where I'm coming from?
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Old 28 December 2005, 13:05   #5
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I changed over to a piranha plastic prop. Was very disappointed, it was the same pitch as the original aluminium one, the rmp to speed stayed the same but I lost power, it was like putting another diver in the boat. Just keep it as a spare and use the old one now. Think that the blades must flex despite what their advertising said. That was a 17inch pitch on 85 suzuki.
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Old 03 January 2006, 00:25   #6
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Hmmm. Exhaust gas travels from the powerhead, out the exhaust ports, down the lower unit, and out from the prop nacelle, either through or over the prop.

Personally, I don't think the hub size on the prop is going to make much of a difference in exhaust flow. Too much other resistance. It also won't create less drag, as the nacelle leads it, and has a fixed cross sectional area.

I'm not real clear how a smaller hub diameter will increase exhaust flow, either. Seems backwards. To get more flow, you want a larger opening. Smaller will cause more backpressure, higher exhaust velocities, and perhaps *less* flow.

OTOH, I could very well be wrong.


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