Technical Talk

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Ernie Lazenby

A technical question.

Post by Ernie Lazenby » Tue Aug 21, 2018 2:40 pm

K7 in its original form had flotation foam inside the sponsons its purpose obvious. I note the new sponsons do not have any foam and are thus lighter than the originals.. This may be why she seemed easy to get onto the plane. Donald and Leo said she was difficult to get over the hump. I presume a calculation was done to see what buoyancy would be needed to keep the rebuilt K7 afloat/partially afloat should the worse/ unexpected happen. The gas turbine model I made has the sponsons filled with a two part buoyancy foam and will keep it from completely sinking if an accident occurs. The back will drop down because there's nothing from the air intakes backwards to keep it afloat but the sponsons will be sticking up a little out of the water, provided of course they don't become detached!
Yes two tons of machinery is different- just asking the question.

BTW Have you got an exact weight for K7 as she is now fully fuelled up?

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Renegadenemo
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Re: Technical Talk

Post by Renegadenemo » Tue Aug 21, 2018 7:39 pm

K7 had foam in the sponsons because they leaked like sieves and not to afford buoyancy. Think about it... they wouldn't crush at the surface and if they remained air tight they'd afford more buoyancy empty than filled if with foam. Expanding foam isn't light as anyone who has ever carried a bucket of it in its pre-expanded condition will testify. We tried to make our sponsons watertight thus saving a minimum of 36kg at the pointy end and that's without any water the foam might soaked up over time. We still had some ingress into the right-hand wedge but fluorescent dye and a black light will soon show where that got in. We've always known our sponsons would be like corks compared to the originals and that's just how it played. Happy with that.

PS - if she fills with water she sinks - simple as.
I'm only a plumber from Cannock...

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longarmedgibbon
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Re: Technical Talk

Post by longarmedgibbon » Wed Aug 22, 2018 3:17 pm

What was the reason to change the bilge pump water out let bill ? I thought it came out those little side pipes. Ian lazenby

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Mike Bull
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Re: Technical Talk

Post by Mike Bull » Wed Aug 22, 2018 3:19 pm

The temporary new outlet is to suit a modern high capacity pump inside the transom. It earnt it's keep, too!

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rich1608
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Re: Technical Talk

Post by rich1608 » Wed Aug 22, 2018 4:03 pm

The modern high capacity bilge pump and modern radio got me thinking... does K7 have an engine-driven generator or is she entirely dependent on fully-charged batteries in good condition? Actually, thinking about it the modern radio probably uses less power than the original.

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Renegadenemo
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Re: Technical Talk

Post by Renegadenemo » Wed Aug 22, 2018 4:09 pm

There's no power generation on the boat. Only batteries. We fitted new ones and keep them charged between runs. They go flat pretty quickly.
I'm only a plumber from Cannock...

"As to reward, my profession is its own reward;" Sherlock Holmes.

'Sometimes you gotta be an S.O.B if you wanna make a dream reality' Mark Knopfler

quicksilver-wsr
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Re: Triumph to Tragic in one fell swoop.

Post by quicksilver-wsr » Fri Aug 24, 2018 11:32 am

Techteam wrote:
Fri Aug 24, 2018 10:53 am
To the 2 pilots, Well Done ! It must of been daunting to take on something that nobody really knew much about and take it safely to what is on water quite a speed.
Speaking of the two "pilots" - not a word I use in relation to boats: prefer "driver" myself ...

For me it was a hoot to see one of the great WWSR fallacies well and truly trashed. The story went that you had to be a well-experienced powerboat driver to drive a WWSR boat. You had to be able to "read the water" - was the quote - and that, apparently, took years and years of experience of driving a boat at high speed, and by-golly, you'd better believe it.

Then an RAF jock gets into the cockpit of a WWSR boat and isn't at all shoddy when it comes to "reading the water".

Ah, but he is an ex-Red Arrows pilot!

Yes, but he's not a powerboater. And that's the point.

If there's one thing that bit the dust at Bute it was the myth that you have to be an experienced powerboater to drive a WWSR boat well.

But in actual fact, that had already been demonstrated by Donald - way, way back - with K4.

Just minutes into his first few tries, he'd mastered it. "He took to it immediately - like a duck to water," Leo told me in 1973.

And Donald wasn't a pilot then, either. His PPL came later.

Nigel

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Re: Triumph to Tragic in one fell swoop.

Post by Techteam » Fri Aug 24, 2018 11:56 am

Nigel

I look forward to you telling us all how easy it was.

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Re: Triumph to Tragic in one fell swoop.

Post by quicksilver-wsr » Fri Aug 24, 2018 12:09 pm

I didn't say it was easy - I said you don't have to be an experienced powerboat racer.

As just proved by Stewart.

If the truth gets up your nose, go and see a doctor.

Nigel

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Mike Bull
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Re: Triumph to Tragic in one fell swoop.

Post by Mike Bull » Fri Aug 24, 2018 12:33 pm

Stew's biggest comment a few times was that it was 'just like a Hawk'.

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