UK-Cherub Forum
Cherub Chat => Tech Chat => Topic started by: Tim Noyce on March 05, 2009, 12:36:21 PM
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The lovely new ply built cherub in France has been coming along well since the last update, I discovered this on breizh skiff so thought I would share the ongoing story. It looks great!
http://www.breizhskiff.com/index.php?option=com_fireboard&Itemid=74&func=view&id=89968&catid=10 (http://www.breizhskiff.com/index.php?option=com_fireboard&Itemid=74&func=view&id=89968&catid=10)
(http://www.breizhskiff.com/images/fbfiles/images/sortie__7_.JPG)
Here is a teaser photo!
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Those racks look wide. What design is that boat built to?
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AFAIK, it's their own design. Fookin' narrow!
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looks nice....like the colour...
is it me or from the side does it look quite deep in the bow - below the mast sort of area?! might just be the picture angle....plus my french is rather limited :)
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Thats not the only thing worth looking at. It seems to have gone un noticed that there is a stepped hull formation at about the aft quarter of the boat!
(http://www.breizhskiff.com/images/fbfiles/images/SNV32906.JPG)
It's not very obvious from most views, but it's there!
(http://www.breizhskiff.com/images/fbfiles/images/SNV32912.JPG)
If you do a google search for the Breizhskiff site, you can googletranslate the page. It's not perfect and some things need to be taken with a pinch of salt, but it makes more sense!
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Is this the same Dude who made this http://www.yachtsandyachting.com/photos/forum/JackSparrow/2005-09-19_112517_P9110369low.jpg (http://www.yachtsandyachting.com/photos/forum/JackSparrow/2005-09-19_112517_P9110369low.jpg) the LT300? Just looked like it in the background?
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That's a bit nuts! Cheeky Frenchies, what are they up to?
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http://74.125.79.132/translate_c?hl=EN&ie=UTF-8&sl=fr&tl=en&u=http://www.parlier.org/hydraplaneur/bateau/innovations.php%3Flang%3Dfr&usg=ALkJrhg9bPPx0K09TP_rwLZkeUB2CzZ0GQ
hmmmmmm :-\
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My understanding is the step causes aeration under the hull, reducing friction and encouraging the hull to plane earlier, with the trade-off being reduced stability when cornering (in a powerboat application anyway.. how it relates to a dinghy which has a tendancy to heel in a straight line i don't know).
How does this fit with the rule stating that "chines shall be fair and continuous curves"? From top-down this could be true, but in side profile they certainly wouldnt be.
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the chine in front of the step looks over 2 meters and is fair.
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Does a step not constitute the continuation of a chine then? Is the step and final hull section considered a different chine to that before the step?
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you could see it that way i.e it is another chine. Or you could see it as 'not fair and continuos'
where's the technical officer when you need him?! ;D
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Its been a very long time since a step was tried on a dinghy. The Nervous Breakdown Moth of the 60s is the most recent I can recall. I should be interested to see how it goes, but would fear Marineritis.
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Its an interesting idea... but from what I know of steps in powerboats id expect some brown wetsuits on the bearaways...
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They do not hang around over there!
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Those are Halo's sails - Has anything happened to Halo?
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Doesn't Halo have a cameo role in the garden pic?
The one in which one garden has more fun boats than most dinghy parks.
Not sure if I was more impressed with the garden or the boat both looked very good.
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This design has been drawn by Thomas, owner of Halo Jones and Laurent owner of Halo Wind.
It's a prototype in plywood/ epoxy / carbon using Halo's mast, rudder, board and sails at the moment. The boat is really beautifully built.
It's a 2 steps narrow hull. The design is really done for heavy weather and hight speeds. I tried it in light winds and I found it quite tricky compared to my Slug.
Ghislain
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So, does anybody know if that stepped-chine idea actually worked on the French boat?
Was the ply hull down to weight and strong enough to take the rig loads?
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The reason I ask is it's an idea I've thought about many times since seeing the F1 Powerboats racing on the Tay in about 1994. They had 2 or 3 steps in the bottom of their hulls. As I understand it the exhaust gases from the engines were forced out under the hull in the vertical surface of the steps. This led to a big reduction in the surface tension of the water under the hull and higher planing speeds. Obviously we don't have any exhaust gases to play with (actually that's debatable, on the Team Scotland boat anyway), but I've often wondered if a very small step (say no more than 10mm) about 1m forward of the transom, with fine tubes led down from the deck area entraining air by the venturi effect would be enough to reduce drag under the planing area of the hull. Or would trying to plane on a suface of froth actually suck the hull down and make it slower?
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I do know that the stepped boat no longer has a step. It seemed to go ok at Bordeaux. Don't know whether it is down to weight or not.
I'll post something on the French forum now.
W
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http://www.breizhskiff.com/forums/10-la-vie-des-associations/86610-nouveau-cherub-en-france.html
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(http://www.breizhskiff.com/images/fbfiles/images/peinture2.JPG)
No messing!
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One of the reasons I never understand what is going on breizhskiff (I now realise) is that their forum posts are the other way up to ours!
http://www.breizhskiff.com/forums/10-la-vie-des-associations/86610-nouveau-cherub-en-france.html