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sailingrugger

Bulbous Bows on racers

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So with the discussion about the Farr 11s' angled flared bow as opposed to being plumb, I was thinking to myself... self, why not make an aircraft carrier with a stick on it?

 

I realize these bows are designed for stability in heavy seas, at a steadied-level forward movement (no heel)... so I would imagine the effects would be (slightly or much) less desirable going upwind... but I do know they are great for chop. Another thing is, it would probably effect the planing ability off the hull as well? Then again, it wouldnt have to be dense and add weight to the bow... could just be a hollow bulb and maybe even add some bouyancy as a result? Any thoughts or am I being a complete moron here? ;-)

 

I am sure it had to have been tried out at some point by now....

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Bulbous bows are designed for stability in heavy seas?

 

 

Bulbous women are designed for stability on water beds. :lol:

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I recall this being tried in England during the seventies, I not it's either good or bad, but when tried, it did not get good results...I think it is technique better suited to heavy displacements.

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Bulbous bows are designed to "cancel" out the hull's bow wave by inducing their own wave set that has the same frequency, but opposite phase, thereby reducing wavemaking resistance.

 

To make this work, the boat's speed has be within a very tight specified range and the amplitude of the pitching moment has be be realtively small to keep the bulb at the proper depth.

 

Neither of these conditions can be met on a small-ish hull form. The additional wetted surface and form drag eats you up.

 

Was tried in the 70's on 6 Meters and flopped horribly.

 

(My senior design project at U of Michigan was a 6 Meter (1982) and we researched this extensively.)

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Bulbous bows are designed to "cancel" out the hull's bow wave by inducing their own wave set that has the same frequency, but opposite phase, thereby reducing wavemaking resistance.

 

To make this work, the boat's speed has be within a very tight specified range and the amplitude of the pitching moment has be be realtively small to keep the bulb at the proper depth.

 

Neither of these conditions can be met on a small-ish hull form. The additional wetted surface and form drag eats you up.

 

Was tried in the 70's on 6 Meters and flopped horribly.

 

(My senior design project at U of Michigan was a 6 Meter (1982) and we researched this extensively.)

 

 

I understand what they do -- I guess my question revolved more specifically around how they perform on a heel? But I guess I never considered how a short waterline would effect it too... Now, I take it you considered it on a displacement hull, but what about a planing hull? Just a thought?

 

Lesbian robot... must be that time of the month I guess

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was done in the early 70's by a MIT prof. I think it was Jerry Mildurn (sp?) boat was an IOR cat rigged boat "Cascade"

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Do you get stupid when I get my period? Bulbous bow+planing hull=Epic failure.

 

Why don't I just put wings on my car so that it will fly? If a cork floats why can't it go up a waterfall? If I eat food and poop what I eat, why can't I eat my poop? Oh, the wonderous world about me is so confusing!

 

Maybe you ater too much paste as a child, or a diet compriused exclusivly of crayons and shit you licked off of the short buss window stunted your mental growth, but you clearly are not very bright.

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At least one Anarchist from this site should be able to give us an informed opinion. IIRC, the cats Nice Pair and Wahoo have bulbous bows. I can't remember what kind of boat those are though. Nice Pair seems to do well in racing.

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Why don't I just put wings on my car so that it will fly? If a cork floats why can't it go up a waterfall? If I eat food and poop what I eat, why can't I eat my poop? Oh, the wonderous world about me is so confusing!

 

Maybe you ater too much paste as a child, or a diet compriused exclusivly of crayons and shit you licked off of the short buss window stunted your mental growth, but you clearly are not very bright.

LR is in fine form today!

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was done in the early 70's by a MIT prof. I think it was Jerry Mildurn (sp?) boat was an IOR cat rigged boat "Cascade"

 

No, Jerry tweaked the shape of the bow/stern pretty radically in addition to the cat-ketch rig but it was not bulbous and not for that purpose. It was just exploiting a loophole in the IOR rule at that time. In fact, he didn't go crazy with the chainsaw on the hull until the 2nd year of the boat after they plugged some holes after the initial success.

 

And it's Milgram....possibly one of the strangest, albeit most brilliant guys I have ever met.

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The questio itself really isn't as stupid as I made it out to be. I am just cranky from too many nights stayiong awake listening to Joe Buck and Tim McCarver attempt to verbally labotimize me.

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At least one Anarchist from this site should be able to give us an informed opinion. IIRC, the cats Nice Pair and Wahoo have bulbous bows. I can't remember what kind of boat those are though. Nice Pair seems to do well in racing.

 

They are both cats, Nice Pair is a Crowther Super Shockwave (38'). Wahoo is a 50' dust collector.

 

They do have enlarged bow sections but I believe that is just to maximize the forward volume. Hobie had it right, this is a displacement mode optimization to minimize wave generation, absolutely not something you would think about on a cat. Think container ship and fuel efficiency.

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Bulbous women are designed for stability on water beds. :lol:

 

Bulbous women sink into waterbeds hence stability when they hit bottom. Different design criteria entirely...

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Bulbous bows actualy did survive into modern yacht design. Someone hired to do the drafting for a famous N/A had the sketch on his desk upside down and the Bulb Keel now so famous on race boats came to be

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They are both cats, Nice Pair is a Crowther Super Shockwave (38'). Wahoo is a 50' dust collector.

 

They do have enlarged bow sections but I believe that is just to maximize the forward volume. Hobie had it right, this is a displacement mode optimization to minimize wave generation, absolutely not something you would think about on a cat. Think container ship and fuel efficiency.

 

So there could/would be no inherent lift from putting a bulb-like object projecting from the bow/leading edge of the hull?

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There was an ugly Elvstrom /kjsomethingoff production cruiser (Aphrodite - not the pretty 101) out in the 70's that had a ship type bulbous bow. For a boat that motors (cruiser/ motorsailer) it would be a good idea if you have plenty of power. Not so good for sailing. Certainly works well on ships and you see them on smaller and smaller ones.

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So there could/would be no inherent lift from putting a bulb-like object projecting from the bow/leading edge of the hull?

 

 

What is there about "bulb" and "lift" in the same sentence is it that rings some bell in your mind? Planing means that you are not IN the water, you are ON the water. Bulbs are a WAVE forming hull extension. Planing tries to aVOID HOwever much possible, making waves.

 

Got it?

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So there could/would be no inherent lift from putting a bulb-like object projecting from the bow/leading edge of the hull?

You could design it to give you lift, but only at an extreme cost in drag. I cannot imagine the tradeoff would be worth it, but if you really want a research project, good luck........

 

Bulbous women sink into waterbeds hence stability when they hit bottom. Different design criteria entirely...

I'll take you at your word on this one.......

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Bulbous women sink into waterbeds hence stability when they hit bottom. Different design criteria entirely...

 

 

Thanks for the insight.

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If the woman displaces more water than your waterbed holds stop sexing immediatly and find a different woman, or stop trying to make bangfuck in a watercrib.

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If the woman displaces more water than your waterbed holds stop sexing immediatly and find a different woman, or stop trying to make bangfuck in a watercrib.

 

 

 

:lol::lol::lol:

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There was an ugly Elvstrom /kjsomethingoff production cruiser (Aphrodite - not the pretty 101) out in the 70's that had a ship type bulbous bow. For a boat that motors (cruiser/ motorsailer) it would be a good idea if you have plenty of power. Not so good for sailing. Certainly works well on ships and you see them on smaller and smaller ones.

 

Elvstrom, did indeed, do several designs with a bow bulb. IIRC, one was a early Seventies IOR Half-ton. Here is a photo of a later cruiser, the Coronet 38.

 

1011406.jpg

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So what you're all saying is... this is a bit impractical?

 

 

LOL..what's it rate

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Do you get stupid when I get my period? Bulbous bow+planing hull=Epic failure.

 

Why don't I just put wings on my car so that it will fly? If a cork floats why can't it go up a waterfall? If I eat food and poop what I eat, why can't I eat my poop? Oh, the wonderous world about me is so confusing!

 

Maybe you ater too much paste as a child, or a diet compriused exclusivly of crayons and shit you licked off of the short buss window stunted your mental growth, but you clearly are not very bright.

Being a grad of RIT, I'd say he is a photog student and not an EE or ME. Either that or a freshman and hasn't even taken the real courses yet

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Was tried in the 70's on 6 Meters and flopped horribly.

 

(My senior design project at U of Michigan was a 6 Meter (1982) and we researched this extensively.)

 

I give you Paul Elvstrom and Jan Kjaerulf's KA 9 Prince Alfred (sorry for the poor image quality). The boat is now in Switzerland, de-bulbified (castrated?) and called La Difference:

post-6597-1193690902_thumb.jpg

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I give you Paul Elvstrom and Jan Kjaerulf's KA 9 Prince Alfred (sorry for the poor image quality). The boat is now in Switzerland, de-bulbified (castrated?) and called La Difference:

 

That's the one!!!!

 

Its picture is next to "pig slow" in the dictionary.

 

The only meter boat slower than that was Mariner.

 

"Even a turd is pointed at both ends"

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That's the one!!!!

 

Its picture is next to "pig slow" in the dictionary.

 

The only meter boat slower than that was Mariner.

 

"Even a turd is pointed at both ends"

 

 

....and the reason is.....keeps all the a/h's from slaming shut :(

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So what you're all saying is... this is a bit impractical?

That would certainly be impractical. It would make much more sense as a masthead rig with sym kites.

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So what you're all saying is... this is a bit impractical?

 

 

Needs foils. Doug should be here shortly...

 

 

Also needs sail foils to be a whole new shade of orange

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Needs foils. Doug should be here shortly...

 

 

Also needs sail foils to be a whole new shade of orange

 

 

And add that german designed(?) "lifting" spinny while your at it.

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The reason that cargo ships and aircraft carriers have bulbous bows and that they work is because they have a steady, reliable form of propulsion so they can overcome the low speed drag and reach the cruising speeds where the bulbous bow does its job. No way in hell would a sailboat ever work with one, because it would slow the boat down so much at low speed that it would need around 40 knots of wind to work.

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As others have said, the bulb doesn't work so well because they are pretty much designed for a certain speed/length ratio, suffer in a chop, add wetted surface. One of the other things that hasn't been mentioned is the bulbed boats tack slow, like a square rigged barge, pretty much consigning you to doom and unmitigated failure any time you're in the vicinity of another race boat.

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otoh bulbous bows seem to work well on trawlers. :P

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No! Good god, will one of you ignorant fuckers look up "bulbous bow" on Google?

 

Bulbous bow= wave making

 

Wave piercing bow= exactly what it fucking says

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Aren't wave piercing bows the closest sailing design analogue to bulbous bows? (see e.g. A-class cat bows shown below)

 

22af16e0.jpg

 

22cf4680.jpg

 

 

Read the article all the way through. Reasons for the bow: Reduced weight, less wetted surface, less windage, reduced pitching while providing adequate buoyancy.

 

Not wave-piercing really - maybe chop-shredding - and certainly not on a hull form that is sailing at displacement (i.e. wavemaking) speeds.

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No! Good god, will one of you ignorant fuckers look up "bulbous bow" on Google?

 

Bulbous bow= wave making

 

Wave piercing bow= exactly what it fucking says

 

I allways thought Flying Scotts had Bulbous Bows above the water, try and pierce a wave with that dick head kinda the reverse of penis envy

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No! Good god, will one of you ignorant fuckers look up "bulbous bow" on Google?

 

Bulbous bow= wave making

 

Wave piercing bow= exactly what it fucking says

But like it kinda sticks out, you know, like its bulging or bulbous like...you know

 

Maybe he should change the college association from RIT to RIF. <_<

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No! Good god, will one of you ignorant fuckers look up "bulbous bow" on Google?

 

Bulbous bow= wave making

 

Wave piercing bow= exactly what it fucking says

 

Sorry Homosexual Automaton, perhaps you misunderstood. I did not say wave piercing = bulbous bow. I said wave piercing = closest sailing design analog of bulbous bow. "Wave piercing" is probably not the best terminology, but should be thought of as shorthand for: a bow shape for which the enclosed volume above the waterline is less than the volume below the waterline, for at least 20% of the waterline length aft of the stem.

 

If you take a bulbous bow and smooth out its profile to match the rest of the bow you get something that looks like a "wave piercing" bow.

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Sorry Homosexual Automaton, perhaps you misunderstood. I did not say wave piercing = bulbous bow. I said wave piercing = closest sailing design analog of bulbous bow. "Wave piercing" is probably not the best terminology, but should be thought of as shorthand for: a bow shape for which the enclosed volume above the waterline is less than the volume below the waterline, for at least 20% of the waterline length aft of the stem.

 

If you take a bulbous bow and smooth out its profile to match the rest of the bow you get something that looks like a "wave piercing" bow.

 

IT MAY LOOK LIKE IT, JUST LIKE IF YOU SMOOTHED OVER A 56' CADDY YOU MIGHT END UP WITH SOMETHING THAT LOOKED LIKE FORD TAURUS...OK, I'll stop yelling. It is not a "close design analog." The friggin design problem and intent is entirely, completely, absolutely different.

 

Give it up.

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IT MAY LOOK LIKE IT, JUST LIKE IF YOU SMOOTHED OVER A 56' CADDY YOU MIGHT END UP WITH SOMETHING THAT LOOKED LIKE FORD TAURUS...OK, I'll stop yelling. It is not a "close design analog." The friggin design problem and intent is entirely, completely, absolutely different.

 

Give it up.

 

Perhaps you too have difficulty reading...I did not say "close design analog." I said "closest design analog." And I defined "wave piercing" as "a bow shape for which the enclosed volume above the waterline is less than the volume below the waterline, for at least 20% of the waterline length aft of the stem." The first part of this definition also applies to a bulbous bow.

 

I have not seen another bow design to which the above definition applies. Thus, the closest design analog to a bulbous bow that has been used effectively in sailboats is a "wave piercing" bow according to the above definition.

 

I agree that that at least part of the "friggin design problem and intent is entirely, completely, absolutely different." However, although the problems solved by the two designs are different, the designs are similar (both designs fit the definition above).

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What is there about "bulb" and "lift" in the same sentence is it that rings some bell in your mind? Planing means that you are not IN the water, you are ON the water. Bulbs are a WAVE forming hull extension. Planing tries to aVOID HOwever much possible, making waves.

 

Got it?

 

Does this imply that you think the good ship Anne has a bulbous bow ? ? ?

 

That could account for the boatspeed problem!!!??? :blink::unsure:

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While the bulbous bow hasn't hit mainstream in racing sailboats, between the wave piercing (reverse bow) catamaran described earlier in this thread, along with the new Leopard with its reverse bow, it appears that designers are slowly working their way towards that extended waterline length that used to be stuck out the back end of the boat in the past and is working its way forward in design.

 

DSC_0109.jpg

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Showing a resemblance in some particulars between things otherwise unlike.

 

Based on the above definition of analogous, and since both designs fit at least a part of the definition I used above to describe a "wave piercing" bow, I submit that the designs are indeed analogous.

 

You may submit, but its gonna get rejected. Just because the bow profile in one design is a little raked aft and the other design looks like its got a major woodie in search of a hump-backed whale doesn't mean they are analogues of each other.

 

Particularly if you get rid of the "wave-piercing" misnomer/misapprehension. The cat bows are not "wave piercers" and they certainly aren't "wave-makers". As noted above, the raked cat bows and the freighter bulbous bows are designed as they are for entirely different performance reasons.

 

You have approached the limit.

 

QUOTE(Asymptote @ Oct 29 2007, 02:17 PM) *

What is there about "bulb" and "lift" in the same sentence is it that rings some bell in your mind? Planing means that you are not IN the water, you are ON the water. Bulbs are a WAVE forming hull extension. Planing tries to aVOID, HOwever much possible, making waves.

 

Does this imply that you think the good ship Anne has a bulbous bow ? ? ?

 

That could account for the boatspeed problem!!!??? blink.gif unsure.gif

 

 

I wouldn't be surprised, but we'd have heard way too much about it if the vain-glorious Weid had incorporated such a hydrodynamic marvel.

 

Still, something besides barnacles, kelp and 18th century hull design has to account for their astounding 2 knots of speed in 24 knots of breeze.

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Read the article all the way through. Reasons for the bow: Reduced weight, less wetted surface, less windage, reduced pitching while providing adequate buoyancy.

 

Not wave-piercing really - maybe chop-shredding - and certainly not on a hull form that is sailing at displacement (i.e. wavemaking) speeds.

 

Read the article all the way through. I believe it says that the A-Class is "an ideal platform to incorporate such a radical wavepiercing hull form."

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