sail69

Keel WTF...

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Just another variant of a tandem keel - albeit not a very good one.

I believe the one below is from a Bavaria - although this one is also not that good IMO.

PR01190208.jpg

This one is a bit better:

tandem-keel.jpg

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9 minutes ago, Somebody Else said:

With such loving maintenance, it's obviously a stellar performer!

 

Well that's a little unfair.

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4 hours ago, sail69 said:

My buddy took this pic in a yard here in New England.

image.thumb.png.87b226c062bf6f8e3dd5ff169417e353.png

This is the latest drug dealers model with the Banksy option fitted. 

 

The drugs are in a pod between the hull and the keel and when the Coast Guard picks up the boat the Banksy option is then activated and the pod drops out 1/2 mile from the Coast Guards base for collection at a time that better suits the drug dealer

 

pulpit

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5 hours ago, 12 metre said:

This one is a bit better:

tandem-keel.jpg

Sailed in the BVI on a Harmony 47 that had a keel just like that. We were unaware that it had anything other than a conventional fin until we dove under it.

No advantages or disadvantages that we could detect.

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Back in the mid-'80s the windsurfer scene saw "twin fins" - which, as the name might imply,  were two, long narrow fins in tandem to forestall "spin-out" on landing jumps.

They were a bit slow and draggy however,  and prone to damage - and,  well...if you just learned how to jump and land correctly,  you could easily avoid spinning out,  so...

 

 

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I am really surprised the front keel wouldnt cause the rear keel issues with disturbed flow. It would be very interesting to see the CFD models and tank testing.

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7 hours ago, jack_sparrow said:

The next and last one being 1992 AC in San Diego, Farrs NZL-20...it tanked.

 

Tanked?  By all indications it was fast.  The sprit fiasco is what did them in I thought.

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7 hours ago, jack_sparrow said:

The next and last one being 1992 AC in San Diego, Farrs NZL-20...it tanked.

NZL 20 Twin.jpeg

nzl20-keel-cupinfo-1310-2 basse def.jpg

NZL didn't tank, it was very fast and almost made it to the finals.  NZL got protested for the bowsprit which rattled their sail handling at the end of the Loius Vitton, and they lost.

The tandem keel in theory gave a bit more foil area for the restricted draft and may have reduced the tip vortex.  But it was probably a minor effect compared to the other major parameters, ie length, beam, weight, sail area.

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1 hour ago, bgytr said:

NZL didn't tank, it was very fast and almost made it to the finals.  NZL got protested for the bowsprit which rattled their sail handling at the end of the Loius Vitton, and they lost.

The tandem keel in theory gave a bit more foil area for the restricted draft and may have reduced the tip vortex.  But it was probably a minor effect compared to the other major parameters, ie length, beam, weight, sail area.

It's funny that the bowsprit on NZL-20 was protested but now that configuration, complete with dolphin striker, is totally legal. All the TP52s are set up like this.

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2 hours ago, trimfast said:

I am really surprised the front keel wouldnt cause the rear keel issues with disturbed flow. It would be very interesting to see the CFD models and tank testing.

Keep in mind that the aft strut on NZL 20 had a flap so it served as a rudder as  well.  One of the major advantages to this arrangement on an IACC boat would be that there were no huge torque loadings on the struts from a long slender (low drag) bulb like you would have with a single central strut.

19934.jpg

But I always thought this arrangement may have been more suitable for the deep bellied 12's since the span of the two struts could each be much greater than a single keel. Especially if you could draw the struts out closer to the ends of the waterline.  You would then have two High AR struts (foils) of about 8 foot span rather than a relatively stubby keel with only about a 5 foot span.

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3 hours ago, Grrr... said:

Tanked?  By all indications it was fast.  The sprit fiasco is what did them in I thought.

 

3 hours ago, bgytr said:

NZL didn't tank, it was very fast and almost made it to the finals.  NZL got protested for the bowsprit which rattled their sail handling at the end of the Loius Vitton, and they lost.

It was not quick in the light which is what killed it in the end, not sail handling. Consensus even in NZ was if they had got through to challenge, America3 would have won anyway.

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16 minutes ago, jack_sparrow said:

 

It was not quick in the light which is what killed it in the end, not sail handling. Consensus even in NZ was if they had got through to challenge, America3 would have won anyway.

Its unfortunate that none of the '92 challenger videos are on youtube.

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2 hours ago, RATM said:

It's funny that the bowsprit on NZL-20 was protested but now that configuration, complete with dolphin striker, is totally legal. 

The sprit was legal, it was the adjustable tack line that wasn't and from memory the Kiwi's argued was barely used if at all. The protest had that race wiped not given to the Italian's.

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18 hours ago, SloopJonB said:

Sailed in the BVI on a Harmony 47 that had a keel just like that. We were unaware that it had anything other than a conventional fin until we dove under it.

No advantages or disadvantages that we could detect.

Drag

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24 minutes ago, Grrr... said:

Its unfortunate that none of the '92 challenger videos are on youtube.

Yes it wasn't until 95 they started to film challenger series live....that at least left us with this classic example of undercooking the design/conditions formula.

The Aust public appeared to lose interest in the AC after this and hence maybe why they have never returned since (except the Young Australia effort in 2000 with old boat and a young Jimmy Spithall).

 

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Presumably the benefits of a long keel for directional stability with less drag, higher lift. Looks a reasonable solution for a cruiser.

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6 hours ago, jack_sparrow said:

Yes it wasn't until 95 they started to film challenger series live....that at least left us with this classic example of undercooking the design/conditions formula.

The Aust public appeared to lose interest in the AC after this and hence maybe why they have never returned since (except the Young Australia effort in 2000 with old boat and a young Jimmy Spithall).

 

Jack,

 

Theres more to the story than most people know about the sinking of One Australia. I was building a boat in Melbourne that was designed by the same designer at the time  and our leading hand built the AC Boat as well so we were told first hand what happened.

 

so what happened ? 

 

The boat was designed for the predicted wind strength in the finals that was about 12 knots. So the design team knew it was pushing the design envelope already for that wind strength let alone for The wind that was blowing that day as it was  22-23 and gusting stronger and the race was very close to being call off. The thing was the it was the top 2 challenging teams for the cup, now if it was the defenders racing the race would of been called off.  He who holds the cup calls the rules.

 

Now not only did the teams have to put up with a max racing wind strength on that day the sea State was also more confused than normal as well. 

 

Now “One Australia” also had problems that day with a primary winch and they were cross loading the headsail as well so the Boat was being over stressed and twisted as well. The AC design rules stated also that the boats had to have a big hatch in the middle of the cockpit floor. Now The boat came off a bigger wave and wind gust and when they landed they folded in half at the cockpit floor hatch. 

 

Now the Kiwi’s pulled there sails down straight away and took their boat home and it sat on the hard for the rest of the regatta. Now I’m told that they also had suffered major hull problems as well that day. The thing was the old boat was still way quicker than any of the other boat that year and the defenders. So they just let it sit there to play mind games with the defenders and the rest is history.

 

Now on a side note, I’m told One Australia when sinking was doing almost close to 18 knots when it hit the bottom some 1200 odd feet down.

 

Pulpit

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24 minutes ago, pulpit said:

Now on a side note, I’m told One Australia when sinking was doing almost close to 18 knots when it hit the bottom some 1200 odd feet down.

Pulpit that reminds I recall them going aground days before??? Was that right.

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23 minutes ago, jack_sparrow said:

Pulpit that reminds I recall them going aground days before??? Was that right.

Jack

 

Not that we were told about. I think they would of kept that quiet if they had anyway.

 

In saying that, the Boat was so close to the design envelope that even the big fella thought it could break at any time and it was that lightly built as they were pushing to the limits in design and built times in order to get the boat to the regatta.

 

Pulpit

 

 

 

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2 hours ago, pulpit said:

Jack

 

Not that we were told about. I think they would of kept that quiet if they had anyway.

 

In saying that, the Boat was so close to the design envelope that even the big fella thought it could break at any time and it was that lightly built as they were pushing to the limits in design and built times in order to get the boat to the regatta.

 

Pulpit

 

 

 

Thanks mate

I will do some digging and let you know to complete your file as the Oracle for One Aust turning into a multi.

Maybe if the Big Fella wasn't standing down the arse end picking his it might have stayed in one piece and then gone on to many NZ parties that happened, never happening :-)

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Here is a quote from Murray: 

“It probably started the day before the race where we hit something and really damaged the bottom of the keel,” the former Etchells world champion said. “It was a metal thing that was blue. We don’t know what it was, but it was enough to destroy part of the keel and we had to replace that overnight."

There were several other factors at play:

  1. At least one of the primaries was not functional so the headsail was being sheeted in with the running back winch.
  2. Deck hardware had been relocated without designer input.
  3. Similarly,  I seem to recall reading somewhere that the previously mentioned hatch had been altered without designer input.  I can't recall whether it was moved or enlarged, but apparently the alteration created a large stress raiser.   This was about the point where the boat folded up.

I don't know if the incident can be chalked up to any single factor, probably a combination - including wind and sea state.  I believe the kiwi boat also suffered damage in that race - although obviously not quite as catastrophic as One Australia

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11 hours ago, pulpit said:

...

Now the Kiwi’s pulled there sails down straight away and took their boat home and it sat on the hard for the rest of the regatta. Now I’m told that they also had suffered major hull problems as well that day. The thing was the old boat was still way quicker than any of the other boat that year and the defenders. So they just let it sit there to play mind games with the defenders and the rest is history....

I think NZL-38 was raced a few more times to finish out the LV Round robins. I can totally believe the mind game bit though.

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8 hours ago, 12 metre said:

Here is a quote from Murray: 

“It probably started the day before the race where we hit something and really damaged the bottom of the keel,” the former Etchells world champion said. “It was a metal thing that was blue. We don’t know what it was, but it was enough to destroy part of the keel and we had to replace that overnight."

There were several other factors at play:

  1. At least one of the primaries was not functional so the headsail was being sheeted in with the running back winch.
  2. Deck hardware had been relocated without designer input.
  3. Similarly,  I seem to recall reading somewhere that the previously mentioned hatch had been altered without designer input.  I can't recall whether it was moved or enlarged, but apparently the alteration created a large stress raiser.   This was about the point where the boat folded up.

I don't know if the incident can be chalked up to any single factor, probably a combination - including wind and sea state.  I believe the kiwi boat also suffered damage in that race - although obviously not quite as catastrophic as One Australia

I remember seeing a high angle photo of that boat and it showed the deck ending in a straight line across right around the mast. I though at the time it looked like a major "stress riser" because it wasn't radiused or tapered back in any way at the deck edge.

Guess where the boat folded?

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So, were the conditions outside the design spec for the class? I had a conversation with one of the A-1 crew who felt strongly it was and the race should never have happened. This was a dude who would not otherwise have found the conditions all that noteworthy. 

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Hugh Welbourn led the appendage design team that did a similar NZL-30 tandem keel idea on GBR-78 Wight Magic for 2003, but with a separate rudder, I think.  It proved very quick at times, but the entrenched feeling was that such experiments weren't worth it despite good results. 

So it was binned in favour of the conventional GBR-71 Wight Lightning which got knocked out before the quarter finals.  GBR-78 was re-fitted with a conventional keel.

27978.jpg

There was an Australian boat in 1992 with the same thing, Spirit of Australia, again before reverting to the normal system.

27796.jpg

With thanks and acknowledgements to the site http://www.americas-cup-history.com/english for these images.

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On 10/11/2018 at 12:48 AM, jack_sparrow said:

The next and last one being 1992 AC in San Diego, Farrs NZL-20...it tanked.

NZL 20 Twin.jpeg

nzl20-keel-cupinfo-1310-2 basse def.jpg

Would that qualify for a "full keel" under the whacko Golden Globe rules?

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5 hours ago, kinardly said:

So, were the conditions outside the design spec for the class? I had a conversation with one of the A-1 crew who felt strongly it was and the race should never have happened. This was a dude who would not otherwise have found the conditions all that noteworthy. 

Kinardly,

 

No the wind conditions were on the limits of the design spec for the class. 

 

The AC have had a max wind limits for year and it’s up to the PRO and the RC to draw the line in the sand as to race or not and to call off a race. That year and that race saw the 2 top contenders racing going head to head and the defenders were in trouble as both the Kiwis and the Oz’s were way faster and the cup was going down under either way. So by letting the race go ahead was in the interest for the defenders and in the end one of the contenders was taken out that day. 

 

Now, all the PRO would of had to say to justify the race going ahead would of been we took wind readings and it was in the rule limits , end of story. Now if it was the defenders racing the race would of been canceled. It just goes to show “He who holds the cup, calls the tune”. 

 

Pulpit

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36 minutes ago, pulpit said:

...So by letting the race go ahead was in the interest for the defenders and in the end one of the contenders was taken out that day. 

Now, all the PRO would of had to say to justify the race going ahead would of been we took wind readings and it was in the rule limits , end of story. Now if it was the defenders racing the race would of been canceled. It just goes to show “He who holds the cup, calls the tune”. 

Seriously? Were the LV cup races run by the defender's PRO?

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23 minutes ago, weightless said:

Seriously? Were the LV cup races run by the defender's PRO?

weightless 

 

Back then the AC rules were all about the “Deed of Gift” and the holders of the cup called most of the shots. When the Deed of gift was  disputed it ended up in court. So the Cup PRO controlled both fleets. What happened was the contenders raced 1 series one week and the defenders would then race the next. 

 

The AC has changed a lot since the 1980’s - 90’s some for the better and others not so. Just think how the cup would look now if the boats still had to be built in its home country and then shipped to the event and the designers and sailors had to be citizens not residents of the teams homes country. Just look at the mix of sailors in all teams that are Oz’s or Kiwis in some countries teams.

 

pulpit

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50 minutes ago, weightless said:

Who was that in '95?

 

weightless 

 

I pass. 

 

All  I know is the cups history has more twists and turns in it than most sporting events and back then “he who held the cup, call the shots” most of the time.

 

Now, how do we prove the keel up the top is the Banksy design  ?

 

pulpit 

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On 10/11/2018 at 7:18 AM, sail69 said:

My buddy took this pic in a yard here in New England.

For several years after the Aussies won the AC, cruisers sprouted Wings for 'faster', after the '92 AC there were a bunch of these tandem keel abominations, more recently we see Open60/VoR style chines & these days they've started with Dali-foils.

 

On 10/12/2018 at 7:10 AM, 12 metre said:

Keep in mind that the aft strut on NZL 20 had a flap so it served as a rudder as  well. 

Both foils turned, no flap.

I found it on the hard one day & took a good gawk/bunch of pics.

M0wiTAA.jpg

u2yAwV2.jpg

8meffmE.jpg

 

 

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Kinda liked the old days of sleds defining what *most* sailors could incorporate (how many club level foiling cats have emerged?) into future performance.

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On 10/13/2018 at 3:32 AM, pulpit said:

Now, how do we prove the keel up the top is the Banksy design  ?

If it shredded itself after purchase, it's the real thing

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1 hour ago, TwoLegged said:
On 10/13/2018 at 3:32 AM, pulpit said:

Now, how do we prove the keel up the top is the Banksy design  ?

If it shredded itself after purchase, it's the real thing

And worth more than pre-shredded.

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