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Author Topic: Everest 1 Cherub  (Read 43348 times)

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Offline phil_kirk

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Re: Everest 1 Cherub
« Reply #30 on: October 15, 2012, 12:26:34 PM »
That is a very light hull shell!

Who's boat is going to be ready for the dinhgy show then?

I would be very grately if one of the new boats could be displayed on the stand.
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Offline Stuberry

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Re: Everest 1 Cherub
« Reply #31 on: October 15, 2012, 01:15:14 PM »
It would be excellent to show on the Cherub stand what can be done very quickly and easily with a simple kit of parts.
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Offline Clive Everest

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Re: Everest 1 Cherub
« Reply #32 on: October 16, 2012, 11:29:37 PM »
May be we could try and build a boat during the weekend.

I suspect that you will want to show a boat built by a perfectionist.
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Offline Clive Everest

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Re: Everest 1 Cherub
« Reply #33 on: October 16, 2012, 11:50:33 PM »
Some concern has been raised both directly and indirectly as to whether my planked foam construction constitutes a multi chined boat that is potentially in breach of rule 4.1.5.

"Chines shall be fair and continuous curves. There will be at least one chine at least 2000mm long. All chines at some point shall be at least 450mm from the centreline. No part of the outer skin above a chine shall be inside a vertical line passing through the chine."

This is from what I have given GB and MK to try and allay these concerns. I hope that it reasures others.

Hi Graham,
I am pretty sure that there is no problem.
 
The mould is planked and the foam planks were glued on with the first (inner) skin.
Once this was cured I faired it with a long board.
This started with drawing transverse lines across the planks and then sanding in a diagonal movement across the planks until the turn of bilge was a fair curve, and the felt tip lines had vanished.
The hull is made of 11 planks in total so the change in angle on each plank is very small and only a small amount of foam needs to be taken off.
The whole process only took me a couple of hours.
 
This section below shows the turn of bilge at the centerboard case. Here the amount of material that needs to be removed during the fairing process is just 1.6mm.
The red is the faired shape.
At the bow and the stern the total amount of material that needs to be removed is less, as the change in angle is less at the stern and the bow the planks taper to just a few millimeters in width.
<image003.png>
It was not my intention to push the rule, but simply to find a construction method that was quick and easy as my time and skill levels are limited.
The boat is currently with Roger Angell I can get him to take some pictures if you like. I suspect that the above will better show the situation.
This picture of the boat under vac for the second skin is the clearest that I have here.
Don’t be confused by the crease in the vac bag or the reflection of the fluorescent light that follow the line of the turn of bilge. It is pretty smooth.
<image005.jpg>
 
Most female molded boats will be made with planked foam just to get the foam to fit. Mine is however multi chined, on the inside only.

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Offline gav_sims

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Re: Everest 1 Cherub
« Reply #34 on: October 17, 2012, 04:59:02 PM »
Short Stealth Merlin?
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Offline dave_ching

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Re: Everest 1 Cherub
« Reply #35 on: October 18, 2012, 08:20:22 AM »
Is this the moth/cherub equivalent of the Harlem Globe Trotters?
The Skippy and Ghoul teams combine for one more project.
Personally I do not think the word perfectionist is one of those key words you think of when thinking of the Cherub class.
I work on the basis that if I try enough times one will be perfect by chance.
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Offline Clive Everest

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Re: Everest 1 Cherub
« Reply #36 on: October 23, 2012, 09:20:00 AM »
I now have a centerboard from Composite Craft.
Thanks for PJ for organising the build in parallel to his.

I hope that there is plenty of water at Babbercombe.

As soon as we are back from half term holiday I can build a case and the hull build can get going again.

Clive
« Last Edit: October 23, 2012, 09:08:02 PM by Clive Everest »
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Offline john_hamilton

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Re: Everest 1 Cherub
« Reply #37 on: November 08, 2012, 09:56:23 AM »
your crew is going to need a centerboard crane to pull that up!!!
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The pessimist complains about the wind; the optimist hopes it will change; the realist adjusts the sail

cherub 2645 - cheese before bedtime

Offline JimC

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Re: Everest 1 Cherub
« Reply #38 on: November 09, 2012, 08:55:28 AM »
You can always make 'em shorter, but longer is hard work...

Clive, how long is that one? There used to be a 5'9" limit in the rules, but we dropped it because no-one had made one that long for many years.

Back in the 60s max length boards were common in the UK, and pivoting centrebpards, not daggerboards. Slot gasket hell!
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Offline Clive Everest

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Re: Everest 1 Cherub
« Reply #39 on: November 09, 2012, 11:09:43 AM »
1660mm or 5'5"
I may well be cutting it down a bit.
I will also be starting a petition for dredging of Chichester harbour.

I have put the board slightly further forward than most modern Cherubs (~100mm forward compared to the E6, This is the same as Ronin and 170mm forward of the Deamon design.)
Moving the board forward helps in light winds as the centre of yaw is moved forward and the immersed bow sweeps less water when trying to steer to small shifts and waves.
It also helps reduce the lee helm when the kite is up.
Moving it back helps in strong winds as the bow is up, so sweeping is not an issue and the natural center of yaw is further aft.
The forward position allows a slightly smaller centerboard and a slightly bigger rudder to give the same foil loading, so that the leeway angle and drag are the same.

We are also going to be using a gnav so sailing with it raised should not be an issue.

Clive
« Last Edit: November 09, 2012, 11:21:41 AM by Clive Everest »
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Offline phil_kirk

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Re: Everest 1 Cherub
« Reply #40 on: November 12, 2012, 11:20:01 PM »
What cord's are we using for centreboards these days.

We went a bit conservative with E-numbers to keep the CLR nearer the hull with a cord of 300mm.  I'm now thinking that a smaller cord and more high aspect and perhaps slightly lower area foil would be faster and just wondering how small a cord we can get away with.

Our board is 1500mm long with 300 mm in the hull. Not extreme by the current designs.
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Offline Clive Everest

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Re: Everest 1 Cherub
« Reply #41 on: November 13, 2012, 08:08:16 AM »
I shared the centerboard and rudder build with PJ. The centerboard was built by composite craft.
It has a 240mm cord and 1660 span.
This is the same plan form as Ronin but with a different section.
PJ wanted to use a 225mm cord from a 14 mould, and correspondingly longer span.
I would have happily gone to a lower aspect ratio as I think that we are into very small returns and we sail in a shallow harbour.
We both compromised to get them built as a pair.
My boat has 240mm in the hull. I may well cut the board down slightly.

Clive
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Offline phil_kirk

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Re: Everest 1 Cherub
« Reply #42 on: November 13, 2012, 02:09:05 PM »
Thanks Clive,

I was thinking in the region of 250mm cord so wasn't far off your final solution.

I may have something to do on the sticky weekend then.

A previous post by Dave Roe in a different thread provided a rule of thumb ratio of board area to sail area.  Most people's boards appeared to be larger than this. And 'The Pasta Frenzy' is quick in a blow. 
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Offline Clive Everest

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Re: Everest 1 Cherub
« Reply #43 on: November 17, 2012, 12:58:36 PM »
I have just had a couple of productive days with Rog Angell working on the boat.

We managed to mould a cb case and fit it and get the decks on.
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Offline Clive Everest

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Re: Everest 1 Cherub
« Reply #44 on: November 17, 2012, 01:01:21 PM »
For the 1st half we were able to insert the camera through the holes in the spine and inspect the gunwale join from the inside.
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