Locating water scoops.

[cheddar24manParticipant @cheddar24man]

Yes, it’s me again with another (probably) basic question.

Where should one locate the water scoop?

The rudder will be directly behind the prop but there is room between the prop and the rudder for the scoop.

My thinking is that this way, even at low speeds it should let water in. Off to the side it will only be effective when the boat is moving quite fast.

Advice will be greatly appreciated……………

Thanks in advance…….

[Richard SimpsonParticipant @richardsimpson88330]

I’ve only ever done this once so I’m certainly not an expert, just an idea.  I put my scoop on the bottom of the hull around a third of the way along to ensure it was submerged as much as possible.  The outlet I put just forward of the propeller so the low pressure area in front of the prop helped to pull the flow through the cooling coil as well as the scoop helping to push it.  I’m sure the serious fast electric chaps will have different takes on it.

[Tony HadleyParticipant @tonyhadley]

From Vic Smeed’s 1984 book, ‘Boat Modelling’.

[Richard SimpsonParticipant @richardsimpson88330]

Just a personal thought, I decided to put my scoop the other way round forward of the propeller so I could have the water effectively being pushed as well as pulled but, the main concern I had, was that I didn’t want to interrupt the flow of water on the pressure side of the propeller by sticking the scoop right in the way.

I guess experimentation would be useful but who wants to cut a number of trial holes in a hull just to ‘see what happens’?

[John W EParticipant @johnwe]

hi there, normal practice – the water scoop goes behind the prop as photographs and has already been mentioned earlier on.   There are obviously, in this world, exceptions to the rules – when you race hydro plans etc., the scoops are generally right at the back of the boat and cut at an angle, rather than a scoop.

Here is the other one for you that is out of the ordinary, when I built Leeds Castle a while ago to do a 24 hour race, I incorporated water intakes in the legs of the Aframes which support the prop shaft.   The Aframes were actually made of oval tubing with slots cut in that faced forwards to the bow of the boat.  This actually worked quite well but only when the boat was actually moving.

 

[Richard SimpsonParticipant @richardsimpson88330]

Very clever John, a really neat way of doing it.

[cheddar24manParticipant @cheddar24man]

Thanks guys, all very helpful. As I’m not intending to run this flat out for long times I think initially I’ll suck it and see if the ESC gets hot without any cooling. If it does, ill fit a scoop.

Thanks.

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