Don't Lock Your Props

Ships_Cat

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Don\'t Lock Your Props

Given the continuing disagreement on the "lock or not lock your prop" matter when sailing, we have had the hydrodynamics team here do some investigations and tank testing. The findings have been quite surprising.

Firstly, the tank tests conclusively showed that locked props have higher drag than freewheeling ones. As this is completely contrary to the behaviour of propellers, rotors and turbines in other fluids such as air and fresh water this prompted an intense investigation which is now completed.

What we discovered is that ships' propellers when in salt water (and this only happens in salt water so does not apply on fresh water lakes, for example) have what appears to be an aether in them which when the prop is not rotating is evenly distributed around the prop. It is this eather which causes drag by the mechanism of its field being pulled through the surrounding salt water.

Obviously this is something that has not been realised before so we have named the eather "draghi". The team have managed to describe it in quantum terms now and understand how it works. When the propeller rotates the draghi migrates to the outer parts of the blades and concentrates there. This results in much lessened field and much less drag - this is really quite obvious as we all know that the faster you spin a prop the faster we go, this is because of this drag reduction. Those who have a strong knowledge of field theory (and know all about divergence and curl) will probably immediately see where we are coming from on this.

What we have also now managed to do is trick (a common term in quantum physics) the draghi to flow out of the propeller altogether into the drive shaft so that its field cannot interact with the water at all. This will result in a propellor with no drag whatsoever, whether rotating or not. Its field will also then be available to a suitable pick up in the boat and about the shaft and we believe that we will soon find a way to harness this as a means for very efficient electricity generation by means of the draghi field in the shaft rotating through a salt water cell about it - more to come on this as the final problems are solved.

So, it seems that the matter is now put to rest with conclusive results which will convince even the most sceptical. The results will be published shortly.

John

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alanporter

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Re: Don\'t Lock Your Props

Is drag really the most important aspect ? Sure the wear and tear on the gear box is more important. My boat has a Hurth reversing gear and the manufacturer's instructions say definitely to put the gear into reverse when sailing.

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BrendanS

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Re: Don\'t Lock Your Props

-------------------------------Quantum probablity drive will suprise everyone?
just turn it off

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Ohdrat

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Re: Don\'t Lock Your Props

so if Ships Cat doesn't post does that mean he doesn't exist?

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jimi

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Re: Don\'t Lock Your Props

aha .. but Portious's theory of rotation declares that in a leebowing situation more ground is made to leeward when rotation procceds apace.

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Rob_Webb

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Re: Don\'t Lock Your Props

Holy schmoly Jonh, you're a damn bright cat!

As a (former) physicist I kind of see where this is coming from although on first reading it could almost be a well-articulated wind-up - but I struggle to believe that having met you John! I've always believed that a freewheeling prop must had less drag than a stibbornly static one but I couldn't explain why. Now you appear to have - nice one!

Presume this is all based on a fixed prop? What's the story with a folding prop though? Should it be encouraged to stay unfolded to allow it to spin and thereby reudce it's draghi - or does it have less resistance if it is allowed to fold as originally intended?


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jimi

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Phlagistum & the Wailer Ralley

Ahem .. there are peeps who have suss this out and fly a burgee .. easy to to spot cos they're Flag is them!

<hr width=100% size=1><P ID="edit"><FONT SIZE=-1>Edited by jimi on 04/10/2004 00:18 (server time).</FONT></P>
 

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You guys are up late tonight

It's Monday lunchtime here so I've got an excuse to be online - which makes it v late Sunday night with you guys..... is it Bank Holiday tomorrow or have you all been on the p!ss or something?

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BrendanS

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Re: Don\'t Lock Your Props

For gods sake.....don't open the box. You'll klll the cat !

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Ships_Cat

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Re: Don\'t Lock Your Props

Yes, as we have well discussed before Brendan Heisenberg's Uncertainty Principle was an important part of determining where the draghi was in the prop under various conditions of spin.

John

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Ships_Cat

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Re: Don\'t Lock Your Props

Some more interesting things might come out of this.

One such is we are wondering if this is anything to do with why winged keels work, another point of disagreement among many. Given our results it would seem quite likely that winged keels have less drag if the draghi is concentrating down in the wings. There must be some mechanism encouraging it to do that but we are uncertain why and have yet to conduct tests. It seems perhaps that the speed of the foil through the water must also encourage the draghi to move to the ends and concentrate there.

John



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Rob_Webb

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Re: Don\'t Lock Your Props

Why not go the whole hog and encourage the draghi away from the entire hull and dissipate it to some kind of draghi 'sink' away from the boat - thereby reducing the whole boat's the drag to zero (rather than just the prop).

Result!

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Ships_Cat

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Re: Don\'t Lock Your Props

Yes, we think that might become quite easy to do if we find with winged keels that the speed of the water over a foil influences where the draghi collects. It would seem one could then incorporate a place for it to collect thus reducing the resistance to that of the sink.

John

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Cobra

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But Surely...

Quote "Yes, as we have well discussed before Brendan Heisenberg's Uncertainty Principle was an important part of determining where the draghi was in the prop under various conditions of spin."

...the REAL expert on spin is Alistair Campbell...what are his views on the subject?

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