Author Topic: New 12 Foot Hull Design  (Read 3614 times)

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Offline Neil C.

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New 12 Foot Hull Design
« on: May 02, 2012, 10:35:07 PM »
I think anybody out there with an enthusiasm for the design and build of 12 foot development class racing dinghies will find this interesting. The youtube video of them milling the hull mould was extremely groovy.

http://z10.invisionfree.com/12ft_skiffs/index.php?showtopic=504


Offline Neil C.

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Re: New 12 Foot Hull Design
« Reply #1 on: November 02, 2012, 12:02:39 PM »
Now edging closer to completion. Looks mighty complex to me, but these guys do know what they're doing.

http://z10.invisionfree.com/12ft_skiffs/index.php?showtopic=504&st=60

Offline Tim Noyce

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Re: New 12 Foot Hull Design
« Reply #2 on: November 02, 2012, 12:24:35 PM »
As you say Neil, Looks good but quite a complex build. Considering that the joins are normally the heavy bit I'll be interested to see how it turns out.

Offline BenR

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Re: New 12 Foot Hull Design
« Reply #3 on: November 02, 2012, 01:44:48 PM »
Looks well thought out, Can someone explain the thought behind the stepped chine? I see that the R-Class boats are using it in their L3 and L4 hulls.
2688- Atum Bom

Offline phil_kirk

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Re: New 12 Foot Hull Design
« Reply #4 on: November 03, 2012, 12:06:15 PM »
Steps are often used the assist spray detachment and hence parasitic drag. It could be a rule dodge if they have a chine rule similar to ours. I noticed a small longitudinal step near the bow. Was that what you were looking at. 

Offline kevin_ellway

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Re: New 12 Foot Hull Design
« Reply #5 on: November 05, 2012, 06:56:40 PM »
The 12 ft skiff is an interesting thread. The CFD work that has been done is the sort of thing that only AC teams would have had access to a few years back.

The 12 ft skiff has no hull rules so the rails are not a rules dodge.
The 12 ft skiff and the UK Cherub are developing from the flat planing shapes to more like high speed displacement hulls that will plane. The rails can help in increasing lift from a rounded hull - they kind of act like end plates. They also act to release spray as you suggested. On the 12 ft skiff, one important role is that they add pitch damping - the rig height and fixed sprit make the 12 ft skiff prone to pitching.

I did consider spray rails on the E6 - the inside of the rail was at the chine measurement so it was not a rule dodge. I wanted to keep the rails above the static waterplane so they didn't add drag when sailing upright. I did quite a lot of CFD analysis. Unlike the findings reported on the 12ft skiff site, I couldn't get any improvement of lift to drag. It appeared to be better just to use conventional chines but at a lower deadrise.
The T foil gives the Cherub a huge advantage over the 12 ft skiff. Moths are now about 2 knts faster upwind and around 3-5kts faster downwind than they were maybe 4 years ago. This speed increment has come from foil development. I suspect there is still a lot more performance to come from the development of foils on the Cherub.

Offline Neil C.

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Re: New 12 Foot Hull Design
« Reply #6 on: February 27, 2013, 11:48:43 PM »
The 12 Footer build is really "hotting up" now. (Crap pun of the day).

http://z10.invisionfree.com/12ft_skiffs/index.php?showtopic=504&st=75&#last

N.B. for some reason this link takes you to the middle of the page. Scroll up, not down.

Heated, insulated 20ft shipping container. Very Cherubby.  :)

« Last Edit: February 27, 2013, 11:55:28 PM by Neil C. »

Offline Neil C.

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Re: New 12 Foot Hull Design
« Reply #7 on: March 12, 2013, 12:41:59 AM »

Offline dave_ching

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Re: New 12 Foot Hull Design
« Reply #8 on: March 12, 2013, 07:29:17 AM »
Looks amazing.
The laminating skills alone are impressive.
Amazing how relatively small rule differences make for some large changes to boat layout.