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  #211  
Old 01-25-2017, 06:07 PM
Steve W Steve W is offline
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This approach for rudders has worked well for beach cats for 50 years, its a no brainer really. A bit more difficult for the other foils though.
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  #212  
Old 01-26-2017, 08:12 PM
tspeer tspeer is offline
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Quote:
Originally Posted by JosephT View Post
...Q: Is anyone aware of design concepts for shock absorbing foils and/or rudders such that, in the event of an impact, they will partially retract under load? ...
Instead of partially retracting, it may be sufficient to have them twist when they bend, so as to alleviate the loads. A good example is an airliner's wing. When the swept wing bends, the tip flexes leading edge down. This reduces the angle of attack at the tip, reduces the load, and moves the load inboard where it has less leverage.

There are several ways to implement this characteristic. A swept planform is one way. It will tend to bend about lines that are 90 deg to its axis, and when bent the flow will hit it more to the side that is on the inside of the bend. It's a lot like the effect of leeway on a wing with dihedral.

Another is to lay up a composite structure with fibers that are off the 0 deg axis by, say, 20 deg. That will make twist as it bends. The X-29 used this technique. Even though it had a forward swept wing, when the wing bent, the tip twisted to relieve the load.
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  #213  
Old 01-26-2017, 08:49 PM
sharpii2 sharpii2 is offline
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It looks to me like there is no real satisfactory solution. The foils are like keels in that they take relatively distributed loads and put them on a certain point of the hull.

Unlike the wing example Tom brought up. These foils are damaged by hitting hard or relatively hard objects. Try that with a jet plane wing and the wing shatters.

Since the foil hits its object at a much lower speed, it simply breaks off. Kind of like a sailplane wing hitting an unfortunate skydiver. If it didn't do that, it would hole the hull, maybe taking a huge patch of it, before the foil itself either broke off, or was bent beyond usefulness. Making it either strong enough to take the hit, or resilient enough to shake it off, will require so much extra weight and complexity, it will no longer be up to its original function.

Let's face it guys. To race this particular race with these particular foils is to play Russian roulette.

But the boats can sail safely without the foils, but not nearly as fast.

So, the object is: plan well, race hard, and pray for decent luck. Without it, even with the best skipper, the best boat, and the best planning, you will lose.

And I know the concepts of 'luck' and even 'Chance' don't sit well with our present meritocracy ideology. We want our winners to win because they are the best, not because they are merely luckiest.

If we ever started thinking differently about this, the implications would spread well beyond sports. Trust me.
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  #214  
Old 02-07-2017, 04:27 PM
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schakel schakel is offline
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Hi,

Imoca boats have sheltered safe space where the solo sailor can get protection from wind and waves.
In the already build VOR 65's they prefer flush decks.
Since safety and comfort are high standards on VOR ships.
Why not provide the same sheltered spaces on board the VOR 65's?
Vendee Globe 2016-imocarules-768x510.jpg
Sheltered space IMOCA 60

Vendee Globe 2016-large_ado_150324_knighton_10461.jpg
Vendee Globe 2016-large_map_150323_vignale_00601361.jpg
Flush deck Volvo Ocean racer 65
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  #215  
Old 02-07-2017, 08:33 PM
CT249 CT249 is offline
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Isn't it because the singlehanders spend much less time actively trimming and driving? In addition, shelter sufficient for a Volvo watch crew is going to be pretty big and will interfere with the sail handling, especially around the short courses.

In the early days of the Volvo, when it was the Whitbread, boats had shelters; witness the little dogbox on Flyers I and II. The fact that they have moved away from them probably says something; certainly it's not that they are unaware of them. I think one of the Volvo 60s (Brooksfield?) may have had a hard dodger but that was the last one.
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  #216  
Old 02-08-2017, 12:55 PM
sharpii2 sharpii2 is offline
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Quote:
Originally Posted by schakel View Post
Hi,

Imoca boats have sheltered safe space where the solo sailor can get protection from wind and waves.
In the already build VOR 65's they prefer flush decks.
Since safety and comfort are high standards on VOR ships.
Why not provide the same sheltered spaces on board the VOR 65's
Probably because, with multiple crew, you can set up a watch system where a portion of the crew can get below decks and out of the weather. On a single handed boat, all of the crew (one person) is on watch all the time.

The on deck shelter is probably not worth the performance penalty it is likely to cost.
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  #217  
Old 02-08-2017, 03:13 PM
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JosephT JosephT is offline
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Quote:
Originally Posted by sharpii2 View Post
Let's face it guys. To race this particular race with these particular foils is to play Russian roulette.

But the boats can sail safely without the foils, but not nearly as fast.

So, the object is: plan well, race hard, and pray for decent luck. Without it, even with the best skipper, the best boat, and the best planning, you will lose.

And I know the concepts of 'luck' and even 'Chance' don't sit well with our present meritocracy ideology. We want our winners to win because they are the best, not because they are merely luckiest.

If we ever started thinking differently about this, the implications would spread well beyond sports. Trust me.
Agree completely sharpii2. There is indeed a roll of the dice/Russian roulette with the foils.

Based on the incidents in this last race Vendee really should consider a separate division without foils. If they don't it wouldn't surprise me if a future race sprouted up to accommodate RTW racers who prefer a monohull only.

Something else about the Vendee boats. The hull & foil specs were not 100% consistent across all boats. Design deviations were allowed to some degree. Some boats were mathematically faster and some foils performed better than others. If they considered this round a prototype race of sorts to give these foils a shakedown that's understood, but sooner or later the hull & foil specs need to be 100% identical.
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  #218  
Old 02-08-2017, 08:25 PM
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Doug Lord Doug Lord is offline
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Vendee (and AC too)

I'm not liking the trend toward one design at all. One of the great things about this race was to see the new designs and watch how they performed. I hope they leave the foils and hulls wide open.....
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  #219  
Old 02-22-2017, 09:04 PM
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Doug Lord Doug Lord is offline
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Moments of Impact

From Sailing World:

http://www.sailingworld.com/moments-impact


PS- Conrad, whose boat dismasted is still struggling to make the last few miles
with a jury rig...
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  #220  
Old 02-24-2017, 07:08 AM
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Doug Lord Doug Lord is offline
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More on the last few to finish: http://www.vendeeglobe.org/en/

-Conrad finishes under jury rig....
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Last edited by Doug Lord : 02-25-2017 at 08:45 AM.
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  #221  
Old 02-26-2017, 09:26 PM
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Doug Lord Doug Lord is offline
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Conrad Colman interview: http://www.sailingscuttlebutt.com/20...ck%20here#more

AND(he fell overboard in the Southern Ocean!)

http://www.sailingscuttlebutt.com/20...Read%20on#more
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  #222  
Old 02-27-2017, 07:55 PM
sharpii2 sharpii2 is offline
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75% finish rate is pretty damned impressive for a non-stop single handed race around the world. The first one had only one finish.

I think the evidence is in that these boats, as complicated and expensive as they are, have clearly proven themselves. Canting ballast and lifting foils are here to stay.

From watching some of the videos, it seems to me that these boats actually gave a softer ride while foiling. This is probably because such provided far less opportunity for the light hulls to slam. This may have also decreased the wear and tear on these hulls as well.

Although these boats have only a passing resemblance to the garden variety cruising sailboat, the same could be said for a NASCAR or Formula 1 racer, to an ordinary automobile.

Viva Vendee!
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