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MR.CLEAN

why is it?

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WTF?

 

 

 

We just figured since it was used previously we and the air force thought it worked we would too...

 

JPLG.jpg

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It may just be the photo, but it sure looks as if someone should spend a few hours with some fairing compound and a long board/DA.

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When I saw it first time I also reacted like WTF. After a while I think it is just a X-99 keel with a bulb.

Thinking that way I think it make sence.

 

This one became second in the European Championship. Similar thinking.

http://sundetregatta.blogspot.se/2015/08/orc-european-championship-2015-sugar-2s.html

 

their previous one is the last picture.

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WTF?

 

 

 

We just figured since it was used previously we and the air force thought it worked we would too...

 

JPLG.jpg

 

That design must belong to the Korean War? ;-)

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It must be a keel designed by the US Department of Defense.

ogho2p.jpg

 

There are different ways to look at it ;-)

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Some type of rule beater idea. Look out, we all know what IOR did to hull shape. At least if this is confined only to the keel, it won't create an insane amount of hull torture and the nasty boat control behavior like IOR did. Looks like shit, but who knows, maybe it actually creates enough righting moment to overcome the drag. Could have an end plate effect also.

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WTF is right. Let's see:

 

Low aspect ratio -- high drag for the amount of lift.

Small root -- increase the localized stress far more than necessary without any hydrodynamic advantage

Tapered to the root -- increase cross flow at the hull, effectively canceling the end plate effect a typical keep gets to increase effective aspect ratio

Small bulb -- increase wetted surface and drag, without much advantage for lowering the CG (a little lower, but a lot more drag)

Curved leading edge -- more loss of effective span and therefore aspect ratio, so increase of drag for a given amount of lift.

Two kelp catchers at leading edge without any practical way of clearing the kelp (backing down will just wrap the kelp completely around the keep)

Reduced chord at top of bulb -- nice stress riser, especially on grounding.

 

It would be hard to imagine a less efficient keel.

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From a design perspective, it looks like a nice elliptical leading edge, some compensating for a rule to get the maximum area for the allowed draft, then trying to tuck it all back in at the hull-keel interface to reduce drag.

 

I can see the rationale, but it ain't fuckin' pretty.

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this was for an ORCi event i see. not up to speed on this rating, but if it is like IRC. IRC to my understanding does not like draft or bulbs. top IRC boats of this size have short draft with bulbs or deeper drafts without the bulds. so i guess short drafts need more surface area to bit after tacks and while accelerating. al least that is how i see it.

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Italian ORCi design masterpiece (or failure)

 

More photos: http://sundetregatta.blogspot.hu/2015/07/orc-european-championship-2015-katarina_9.html

 

11709907_10153545210283573_5932513029170

and talk about how IOR caused highly distorted hull shapes? then followed on by IMS? look at the bow and stern treatment on this puppy.

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Italian ORCi design masterpiece (or failure)

 

More photos: http://sundetregatta.blogspot.hu/2015/07/orc-european-championship-2015-katarina_9.html

 

11709907_10153545210283573_5932513029170

 

and talk about how IOR caused highly distorted hull shapes? then followed on by IMS? look at the bow and stern treatment on this puppy.
Yes the bow and stern aren't pretty. The complete package is not much in the looks department, but that would be a clean, fair hull shape compared to an IOR boat. Actually looking at it, it doesn't even come close to the mess IOR created.

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It may just be the photo, but it sure looks as if someone should spend a few hours with some fairing compound and a long board/DA.

Looking at all the pics, you can see the bottom paint is peeling off in places, or got messed up blocking it while on the hard. Maybe the entire bottom, keel and bulb included, needs a complete strip and new bottom paint. The keel finish does have a strange appearance.

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Without ever being involved with ORCi, I'm assuming from the photo that keel area is calculated by measuring the chord at the root and at the multiplying by the span.

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Nothin' wrong with that keel that a good coat of orange paint wouldn't fix.

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that rudder looks as wrong as that keel.

and that bow? never saw angles like that.

Looks like someone took a chainsaw to an old IOR boat and glassed it up 3 feet shorter.

 

Are the toerails really stainless handrails?

 

Not to mention the bottom is not orange.

 

Gotta stop, as my head is about to explode just contemplating this vessel.

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The keel looks like the 1980's fad elliptical thing on my old Olson 911....with a random bulb thingy screwed to the bottom. That keel was very fast upwind if you could find and keep the groove, which I found difficult to do. I think it had something to do with maintaining laminar flow over an unevenly shaped foil. I guess the bulb would help righting moment but it can't improve the flow characteristics.

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If this is fast then all the designers have been very wrong ever since IMS died. Is this the start of the ORCi optimised design?

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If this is fast then all the designers have been very wrong ever since IMS died. Is this the start of the ORCi optimised design?

 

Dingdingding

 

Gotta be rule driven.

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The keel looks like the 1980's fad elliptical thing on my old Olson 911....with a random bulb thingy screwed to the bottom. That keel was very fast upwind if you could find and keep the groove, which I found difficult to do. I think it had something to do with maintaining laminar flow over an unevenly shaped foil. I guess the bulb would help righting moment but it can't improve the flow characteristics.

 

Funny, I was just thinking that.

The keel looks like the one from Airmail, which is an 80's custom Beneteau if my facts are right. I can't find diddly on them in Google but the boat is still sailing, and still competitive. They didn't tack a bulb onto the keel though. :rolleyes:

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I have owned a Soverel 27 with a 300 lb bulb and a J36 with a 600 lb bulb. Both with bilges properly stiffened. Each of them won the St. Thomas Rolex International Regatta 3 times. Draft was deeper and boat was stiffer. Needed less crew. Basically same weight on board but deep down where it counts.

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Looks like a 1984 era Ron Holland MME (Mickey Mouse Ear) elliptical keel with a bulb added.

 

 

^^^^^^^^^^^this^^^^^^^^^ :lol:

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my guess is they wanted more righting moment and more lateral resistance in as shallow a draft as possible, cheaply (not serious, just for the fun factor)

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From a design perspective, it looks like a nice elliptical leading edge, some compensating for a rule to get the maximum area for the allowed draft, then trying to tuck it all back in at the hull-keel interface to reduce drag.

 

I can see the rationale, but it ain't fuckin' pretty.

 

 

Any curvature on the leading edge, really any time the leading edge is not perpendicular to the flow of water, lift decreases and drag increases. The leading edge near the root and bulb has been made substantially less efficient (high drag, low lift). Elliptical leading edges fail. Mickey mouse ears fail. So there is no rational rationale. If you see one, be happy you have a day job, because yacht design is not an area of understanding for you.

 

You don't want the maximum area for a given amount of draft. That's the opposite of fast. Span/area is aspect ratio, and higher aspect ratio is higher lift to drag. Your upwind performance is 100% correlated with lift to drag. Better lift to drag is better upwind performance. Period. Bigger area for span reduces aspect ratio, which reduces lift to drag, which makes you slower to windward.

 

Its simple, but you need to understand how it works. And it works the opposite of how you think it works. You can learn if you want to, that is why Westlawn exists.

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my guess is they wanted more righting moment and more lateral resistance in as shallow a draft as possible, cheaply (not serious, just for the fun factor)

 

I cannot imagine the goal being chased by this designer, as this keel design runs away from effective solutions in each area of keel effectiveness.

 

1) Root shortened by trailing edge curve: reduces end plate effect, reducing effective aspect ratio, increasing drag while decreasing lift more than almost any other thing you can do to a keel. The mirror effect of the end plate effect causes an almost doubling of effective span. Why would you want to reduce this "free" efficiency?

 

2) Curved leading edge: traps stuff at the root, or at the bulb. No way to use a keel stick or loop of rope to clear junk off the keel. Reduces the lift near the bulb rather dramatically (by about half, the lower half foot). Makes the entire lower foot or so of draft (keel and bulb) be all about drag, no lift. Reduces ballast down low. Increases drag down low, so in heavy conditions, more heeling moment even with reduced lift. Hard to imagine a worse concept.

 

3) Much too much lateral area, means more drag, means more heeling moment.

 

4) This is a pretty deep keel -- it sure is not a shoal draft keel. If you really want shoal draft, go with a board not a keel. If this hull had a decent turn of the bilge, it could get by with just lead in the bilge and a board. This turn of the bilge is just about the least effective you can possibly design, so this boat really needs a keel or it will just roll over like a pig.

post-4888-0-34403500-1444161996_thumb.jpg

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It must be a keel designed by the US Department of Defense.

ogho2p.jpg

 

There are different ways to look at it ;-)

 

That plane is from a dept. of defense but the the U.S. one

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Looks like they were chasing reduced root necklace vortice drag....that is the one advantage of a shorter root chord. Tried to reduce the root chord at the top and bottom to reduce that small component of drag. Bad news is any gain there was surely killed by all the other problems this caused.

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It must be a keel designed by the US Department of Defense.

ogho2p.jpg

 

There are different ways to look at it ;-)

 

That plane is from a dept. of defense but the the U.S. one

 

 

Is that the Chinese knockoff?

 

If so, they've come a long way from running shoes and Rolexes. Still unable to actually create anything much though.

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It is an 80's elliptical keel with a bulb.

A sorry attempt to move in to the modern age.

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It must be a keel designed by the US Department of Defense.

ogho2p.jpg

 

There are different ways to look at it ;-)

 

That plane is from a dept. of defense but the the U.S. one

 

 

Is that the Chinese knockoff?

 

If so, they've come a long way from running shoes and Rolexes. Still unable to actually create anything much though.

 

Russian

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When you have changes of geometry at the ends of the foil, there's a vortex bump. The vortex is often reduced by a fairing that extends from the joint at a fairly steep angle with a sharp leading edge to cut down the vortex. Airplanes often use this where the wings attach to the fuselage. Vacanti designed some custom keels for a few boats back in the 80s i think, with some decent performance improvements with this planform.

You can also reduce the vortex at the joint by doing the negative of that, by cutting the chord down instead of increasing, but you will get a reduction in effective span as others have noted. Trade off...

But downwind, you will have somewhat less wetted surface with the "cutouts". You will also have less drag downwind for an equal foil area with a shorter span/longer chord keel than with a long span keel.

 

I'm sure if the designer is worth his salt, he did a trade study to compare multiple keels around typical race courses under the rating rule to see which would work out best most of the time. No one keel will fit the bill best over all courses under all rating systems all the time. This keel looks like it is likely refined for a limited set of circumstances under the rule. Maybe the designer ain't a total idiot.. results over time will tell.

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While everyone is looking at that keel can I ask about what looks like a giant wheel in the cockpit? Am I seeing what I think I am? Can't be.

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Sounds like a good time to ask this question.

 

Can someone tell me what (generally) ORC/ORCi like in a boat? In what ways does it typeform? At this point I have a strong handle on IRC and IRC Optimization but ORC/ORCi is a total mystery to me. Based on the fleet at the worlds this year it seems to like similar types of boats as IRC (???) except at the high end when it punishes being fast and plane-y. Is this right?

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From a design perspective, it looks like a nice elliptical leading edge, some compensating for a rule to get the maximum area for the allowed draft, then trying to tuck it all back in at the hull-keel interface to reduce drag.

 

I can see the rationale, but it ain't fuckin' pretty.

 

 

Any curvature on the leading edge, really any time the leading edge is not perpendicular to the flow of water, lift decreases and drag increases. The leading edge near the root and bulb has been made substantially less efficient (high drag, low lift). Elliptical leading edges fail. Mickey mouse ears fail. So there is no rational rationale. If you see one, be happy you have a day job, because yacht design is not an area of understanding for you.

 

You don't want the maximum area for a given amount of draft. That's the opposite of fast. Span/area is aspect ratio, and higher aspect ratio is higher lift to drag. Your upwind performance is 100% correlated with lift to drag. Better lift to drag is better upwind performance. Period. Bigger area for span reduces aspect ratio, which reduces lift to drag, which makes you slower to windward.

 

Its simple, but you need to understand how it works. And it works the opposite of how you think it works. You can learn if you want to, that is why Westlawn exists.

Really? When rating rules and yacht design collide, going slow through the water can be pretty damn fast in the race results. When yacht designers want a boat to be first to finish, they create a certain type of design. When yacht designers want a boat to win the race results, they create a certain type of design.

 

Some guys want flat out speed and don't care if all the other boats correct over them. Some guys love to manipulate everything they can to rate well and correct over the first to finish yacht.

 

The manipulating of boat design because of a rating rule has been around a very long time.

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I have owned a Soverel 27 with a 300 lb bulb and a J36 with a 600 lb bulb. Both with bilges properly stiffened. Each of them won the St. Thomas Rolex International Regatta 3 times. Draft was deeper and boat was stiffer. Needed less crew. Basically same weight on board but deep down where it counts.

Makes sense!

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