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Author Topic: water scoop location  (Read 14125 times)

triumphjon

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Re: water scoop location
« Reply #25 on: February 08, 2011, 11:09:20 am »

in order to prevent water ingress i shall position the outlets through the stern but above the waterline , for twsting they are draped over the top of the stern ! im currently seeing if i can remotely operate my trim tabs , so will route any pipework around other equipment !  ive got a huntsman 31 which ive got remote tabs so would like the ability to have the same on the 28 .
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bbdave

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Re: water scoop location
« Reply #26 on: March 19, 2011, 11:43:04 am »

Can i just why does the inlet need to be off centre?

Dave
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Circlip

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Re: water scoop location
« Reply #27 on: March 19, 2011, 01:16:05 pm »

If on the centre line, the hole could be "Masked" or shadowed by the Keel or propshaft, on one side it's in clear air (Water really)

  Regards  Ian.
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John W E

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Re: water scoop location
« Reply #28 on: March 19, 2011, 02:01:58 pm »

Hi ya there

If at all possible, place your model in the bath and run motor/motors.   When the motors are running place your hand in the water behind the propeller and you will find that the thrust from the propeller comes from one side of the propeller, depending on which hand the propeller is.

If you imagine the diameter of the propeller as a clock face, for a lef-handed prop, the thrust comes from the propeller from approximately 12 o'clock to 6 o'clock (keeping it on simple terms).  This thrust pattern also depends on the style of blade on the propeller.   

There are several propellers which do not fall into this category of thrust proportions - namely suface-piercing props - doing it this way will indicate which side of the propeller the water scoop will perform best on.

It isnt the case of placing the scoop at 12 o'clock that it has been masked by any keel or anything, it is just that the thrust from the prop isnt at its strongest at this point.

aye
john e
bluebird
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bbdave

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Re: water scoop location
« Reply #29 on: March 19, 2011, 03:20:10 pm »

Right O i see the propshaft or keel creating a shadow but my brain cell struggles with the thrust being different round the diameter

Dave
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Sub driver

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Re: water scoop location
« Reply #30 on: March 19, 2011, 03:26:12 pm »

Dave,

If you still don't really get it...just watch the water go down the plug hole and you will see the flow is around the outside of the vortex and not in the middle, just as it is from a prop.

Hope that makes it clearer .

Regards.
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John W E

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Re: water scoop location
« Reply #31 on: March 19, 2011, 03:29:25 pm »

hi ya Dave

try and keep it simples  :-))

Imagine, as the propeller turns - one blade always cuts fresh water and moves the boat forward one distance of the props pitch.

now, with slip of the prop and cavitation the next blade doesnt get quite the same bite of the water and soforth as the prop moves around.

That is why, if you look at high speed props, how the prop is kept small in diameter and is very coursely pitched.

Best way, is to put model in the bath, run motor, hold boat and put hand behind the prop - MAKING SURE YOU KEEP YOUR FINGERS OUT OF THE WAY .

aye
john
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bbdave

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Re: water scoop location
« Reply #32 on: March 19, 2011, 04:36:06 pm »

Yes the mist clears thanks.

Dave
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neilb

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Re: water scoop location
« Reply #33 on: August 30, 2011, 08:48:08 pm »

Here is  a suggestion for security of pipework in your boat in your boat.

I allways put a doubler on the ends of my sillicone pipe in every boat, it keeps the pipes from
comming off and that stops me filling a boat with water i thought was being used for cooling etc.

Just get a piece of silicone the same diameter that your using and cut a piece 4 mm long.
us e apair of long nosed pliers to stretch it over the silicone pipe before attatching to metal pipes or nipples etc.
This still allows the silicone pipe tp go onto your metal pipes, just with a real good flexible join thats better than tie wraps.

its easiest to see pics below to understand what i mean.



.

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hope this helps understand what i mean



phill :-))




Now this is a brilliant tip thanks for that, this is what i will be doing rather than the cable tie which to me look messy.
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