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Forum Index: DISCUSSION: Dock Talk:
Explain ACC Design? 		Team McLube

 
 


duckydinghy
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May 8, 2006, 7:31 AM

Post #1 of 5 (1676 views)
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Explain ACC Design? Log-In to Post/Reply
noting the letter to the Scuttlebutt editor today, regarding slab-sided boats, can anyone explain why they are faster?


dumbassideaMkII
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May 9, 2006, 3:17 PM

Post #2 of 5 (1648 views)
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Re: [duckydinghy] Explain ACC Design? [In reply to] Log-In to Post/Reply
They arent. It just so happens that the ACC rule favors them. OR, if you have a canting keel and the hull will be upright most of the time, then a slab sided boat may be faster. Look at Nicorette, Wild Oats, Alfa Romeo...they all are pretty much slab sided.


kyle
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May 11, 2006, 7:25 AM

Post #3 of 5 (1627 views)
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Re: [duckydinghy] Explain ACC Design? [In reply to] Log-In to Post/Reply
I think it is because narrow (less surface area/water resistance) is faster


Swuzzlebubble
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May 14, 2006, 7:55 PM

Post #4 of 5 (1597 views)
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Re: [kyle] Explain ACC Design? [In reply to] Log-In to Post/Reply
With most boats at the long & heavy corner of the rule, plus the advances in composite construction, mean that AC boats have extremely large bulbs for the size of boat.
They therefore don’t need the extra stability from crew on the rail nor the form stability of a wider hull.
In fact they have gone for narrower hulls to help allow the hulls to heel over and utilize their overhanging sailing length.

The next issue is they have a large amount of displacement to distribute around the immersed hull.
With length being measured 200mm above waterline plane they want the hull to be as flat as possible (reduced rocker) so the overhangs don’t rise too sharply.
Therefore the hull cross-sections are a flattened ‘U’ profile using as much waterline beam as possible rather than a more circular or ‘V’ section.
The double-knuckle bows and near hard-chined sterns are additional methods of distributing displacement laterally.

Combine narrow overall beam with relatively high waterline beam and you have slab sides.


Jim Bungener
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May 26, 2006, 1:38 AM

Post #5 of 5 (1536 views)
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Re: [duckydinghy] Explain ACC Design? [In reply to] Log-In to Post/Reply
There is a variety of reason:
These cup boats are coming up against the wave drag wall very quickly hence the slab sides allow the boat to sink when heeled and get a longer effective length.
They also give a narrow boat when downwind. And since the bulb keeps us upright who cares about form stability.


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