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Port End Flyer 
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 Topic: Driving Cats hard downwind
Posted: 01 Sep 06 at 1:21pm |
I find myself not fully agreeing with the “You can have too much of a good thing” school as taught by Doug, Worthy & T_Alive, leverage is good in a sailing boat.
But in agreement with JimC most fast planning Mono’s have a relatively gradual change from the pointed bow to a wide flat stern and by lifting the bow (if the wind conditions allow) can reduce the wetted area and promote planning on the wide flatter rear section of the hull, dramatically increasing the boats speed.
Cats generally have “V” shaped narrow hulls that make them displacement sailing craft, albeit very fast displacement craft, and as max speed is in direct relationship to waterline length for displacement craft, tipping the boat fore & aft will only reduce this length and hence speed.
So if flat is fastest for Cats it may explain why the pitchpole is more common in Cats, as Monos have a greater leeway before burying a bow, because it started further above the surface giving Mono sailors more time to react?
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Port End Flyer
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Posted: 01 Sep 06 at 1:20pm |
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Doug.H
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Posted: 31 Aug 06 at 4:54am | IP Logged |
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m_liddel wrote:
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Interesting that the best vmg in monos (when these is breeze) is to twin wire and cats not to. I wonder why it is? |
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I dunno, i thought it was kind of obvious.......Do you realise how much leverage a cat already has just through the weight of the windward hull?? Add another person on the wire and you've got a load more on top of that. Even once youve got everyones weight on the wire on a skiff, im still not sure as to whether you'd have as much leverage working as a cat with one person on the wire.
I could be wrong though.
Doug
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Worthy
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Posted: 31 Aug 06 at 5:50am | IP Logged |
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It is very interesting listening to all the theories and I agree with all of them, especially the one about the leverage.
On an F18 the crews feet is 8ft 6in from the pivot point of the boat, which means their head is 14ft 6in from the pivot point (assuming they are 6ft). This is more than any mono I can think of including an 18ft skiff (I think).
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Tornado_ALIVE
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Posted: 31 Aug 06 at 6:33am | IP Logged |
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Doug and Worthy are both correct..... Not only the leverage from the 8'6" beam or 10' on the T, but also the weight of the hull and rig.
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MRJP BUZZ 585
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Posted: 31 Aug 06 at 6:39am | IP Logged |
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Scooby_simon wrote:
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As for flying a hull over an Oppie, I could not possibly comment...... |
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i heard some where a 18 footer could fit its wing over an oppie
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Medway Maniac
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Posted: 31 Aug 06 at 3:52pm | IP Logged |
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All this quarreling over the relative merits of cats and monos is pointless - you just choose the ride that appeals most to your taste.
Absolute speed is irrelevant: we'd all go faster on a jet-ski (or a moped....). |
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Worthy
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Posted: 31 Aug 06 at 3:54pm | IP Logged |
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Medway Maniac wrote:
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All this quarreling over the relative merits of cats and monos is pointless - you just choose the ride that appeals most to your taste.
Absolute speed is irrelevant: we'd all go faster on a jet-ski (or a moped....). |
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Quarreling wouldn't be my word of choice, we were merely discussing why you sail cats downwind with one person on the wire when you do so with two on a mono.
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Port End Flyer
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Posted: 01 Sep 06 at 1:19pm |
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m_liddell
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Posted: 30 Aug 06 at 7:39pm | IP Logged |
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On the topic of cats being driven hard downwind; why is it that cats never twin wire with the kite up like skiffs do? Surely they could go much faster twin wiring?
Also to depower with the kite up you bear away, often quite quickly. This is recipe for a pitchpole in a cat since it will stuff the leeward hull in at speed. How do you manage this?
Edited by m_liddell on 30 Aug 06 at 7:42pm
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Tornado_ALIVE
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Posted: 30 Aug 06 at 7:44pm | IP Logged |
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boatshed wrote:
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Umm... precisely why cats can't be driven hard downwind. It doesn't even look that breezy and now they'll be utterly dependant decent power boat to up end it. I don't doubt that cats are super quick in moderate winds but that photo sequence by Tornado Alive does absolutely nothing to encourage me into a cat. I doubt if the crew did much wrong, its just that all high performance cats seem to have the same serious vice. |
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Obviously an edjucated commement from someone whom is even partly experienced in multies.
Lucky monos don't have vices. |
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Tornado_ALIVE
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Posted: 30 Aug 06 at 7:55pm | IP Logged |
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m_liddell wrote:
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On the topic of cats being driven hard downwind; why is it that cats never twin wire with the kite up like skiffs do? Surely they could go much faster twin wiring? |
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They can and people have experimented with it, however when trying to achieve maximum VMG downwind, it is not efficient to run that hot. If we overlay a mark, we will twin wire....... or when we are clowning about and not after VMG.
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m_liddell wrote:
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Also to depower with the kite up you bear away, often quite quickly. This is recipe for a pitchpole in a cat since it will stuff the leeward hull in at speed. How do you manage this? |
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Just like a Skiff, you must anticipate the gust. However it will have to be a big gust and a big bear away after you have reacted far to late to cause a nose dive.. It is no different to high performance skiffs monos or yachts.
Edited by Tornado_ALIVE on 30 Aug 06 at 7:56pm
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Port End Flyer
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Posted: 30 Aug 06 at 9:27pm | IP Logged |
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boatshed wrote:
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Umm... precisely why cats can't be driven hard downwind....its just that all high performance cats seem to have the same serious vice. |
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Red rag to a few bulls I would think!? New thread?
And a good attempt at a reply by Tornado_ALIVE under extreme prevarication?
On the whole I would say that Cat classes do pitchpole more than most Mono’s, however they certainly do not capsize as frequently!
However I have never seen a Mono class advertise its boat at the Dinghy Show on its ability to pitchpole, whereas a well know Cat class has!
In agreement with Tornado_ALIVE the three or four boats in the video were not racing, but they all either;-
1/ Pitchpoled on the same moderate gust?
or
2/ The ability shown by the crews to puposely pitchpole their craft in the correct sequence and timing only went to underline the skill of the sailors on show.
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Worthy
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Posted: 30 Aug 06 at 9:53pm | IP Logged |
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Port End Flyer wrote:
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boatshed wrote:
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Umm... precisely why cats can't be driven hard downwind....its just that all high performance cats seem to have the same serious vice. |
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Red rag to a few bulls I would think!? New thread?
And a good attempt at a reply by Tornado_ALIVE under extreme prevarication?
On the whole I would say that Cat classes do pitchpole more than most Mono’s, however they certainly do not capsize as frequently!
However I have never seen a Mono class advertise its boat at the Dinghy Show on its ability to pitchpole, whereas a well know Cat class has!
In agreement with Tornado_ALIVE the three or four boats in the video were not racing, but they all either;-
1/ Pitchpoled on the same moderate gust?
or
2/ The ability shown by the crews to puposely pitchpole their craft in the correct sequence and timing only went to underline the skill of the sailors on show. |
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I know the people in the video and they are some of the best cat sailors in the UK and I can assure you that it was most definately the second of the above two options.
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JimC
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Posted: 30 Aug 06 at 11:20pm | IP Logged |
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boatshed wrote:
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However I have never seen a Mono class advertise its boat at the Dinghy Show on its ability to pitchpole, whereas a well know Cat class has |
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You need to look round a bit more mate: at least one of those mono photos has been used by the class in question at Sailboat more than once. In any case what's so terrible about pitchpoling? If you want to sail a Wayfarer or something that will never pitchpole then that's great, but I won't be in the next boat on a Champs start line.
Edited by JimC on 31 Aug 06 at 12:08am
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Worthy
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Posted: 30 Aug 06 at 11:22pm | IP Logged |
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Edit: Comment removed
Edited by Worthy on 31 Aug 06 at 12:39am
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m_liddell
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Posted: 31 Aug 06 at 1:25am | IP Logged |
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Tornado_ALIVE wrote:
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m_liddell wrote:
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On the topic of cats being driven hard downwind; why is it that cats never twin wire with the kite up like skiffs do? Surely they could go much faster twin wiring? |
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They can and people have experimented with it, however when trying to achieve maximum VMG downwind, it is not efficient to run that hot. If we overlay a mark, we will twin wire....... or when we are clowning about and not after VMG. |
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Interesting that the best vmg in monos (when these is breeze) is to twin wire and cats not to. I wonder why it is? |
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JimC
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Posted: 31 Aug 06 at 3:52am | IP Logged |
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m_liddell wrote:
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Interesting that the best vmg in monos (when these is breeze) is to twin wire and cats not to. I wonder why it is? |
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Not every mono perhaps. Andy Paterson won the Cherub champs last year without twin wiring downhill. There's a reasonably sound guess as to why it mightbe though.
The high powered skiffs very dramatically reduce wetted area at high speed as against more moderate speed, so its worth going high and acceping the penalty. The Cats, on the other hand, not being planing boats, have a much more linear relationship between speed and power, so don't gain so much by sailing the hot angles.
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Close your eyes and "GO FOR IT!" What else do we pay insurance premiums for?
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Port End Flyer
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Posted: 01 Sep 06 at 1:16pm |
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boatshed
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Posted: 30 Aug 06 at 6:43pm | IP Logged |
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Umm... precisely why cats can't be driven hard downwind. It doesn't even look that breezy and now they'll be utterly dependant decent power boat to up end it. I don't doubt that cats are super quick in moderate winds but that photo sequence by Tornado Alive does absolutely nothing to encourage me into a cat. I doubt if the crew did much wrong, its just that all high performance cats seem to have the same serious vice.
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Scooby_simon
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Posted: 30 Aug 06 at 6:58pm | IP Logged |
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boatshed wrote:
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Umm... precisely why cats can't be driven hard downwind. It doesn't even look that breezy and now they'll be utterly dependant decent power boat to up end it. I don't doubt that cats are super quick in moderate winds but that photo sequence by Tornado Alive does absolutely nothing to encourage me into a cat. I doubt if the crew did much wrong, its just that all high performance cats seem to have the same serious vice. |
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What the F%%%%%. That was no where near wipeout time for the Tornado and you can write a Tornado simply.
The Vx's were righted with a power boat in a few minutes.
As for flying a hull over an Oppie, I could not possibly comment......
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Close your eyes and "GO FOR IT!" What else do we pay insurance premiums for?
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Port End Flyer
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Posted: 01 Sep 06 at 1:15pm |
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I found this topic in “Favourite Photos” it obviously didn’t belong there, but was I felt good subject material, so I have attempted to “Copy & Paste” that discussion here to be continued.
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Close your eyes and "GO FOR IT!" What else do we pay insurance premiums for?
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