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Old 08-03-2016, 02:17   #46
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Re: The sexiest Catamaran ever?

Around the late 60's/early 70's I first saw a big cat, a beautifully finished Wharram Oro.

Instant dreams of warm sea, naked chicks, palm-fringed beaches, naked chicks, freedom, naked chicks.............and that was long before I bought the Wharram design book.
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Old 08-03-2016, 02:40   #47
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Re: The sexiest Catamaran ever?

From Ulstein's website (but what do they know, they only make workboats for use in the North Sea)-

The X-BOW hull line design is one of ULSTEIN's main contributions to maritime history. X-BOW vessels are being built at shipyards on many continents. Currently, more than 100 vessels with this bow concept are being constructed or in operational work around the world.

The X-BOW introduces the gentle displacer; a tapered fore ship shape with a different volume distribution as well as sectional angles, resulting in a wave piercing effect at small wave heights, and also reduces pitching and bow impact loads in bigger seas. When comparing fore ship volumes with more conventional, bulbous bow shapes, the X-BOW has more displacement volume starting from the waterline.

The experience is quite amazing. I cannot imagine myself ever travelling with a conventional bow vessel again in winter time.
Captain of the AHTS 'Bourbon Orca​'

While a traditional bow vessel rises on the waves and then drops violently onto the surface of the water, an X-BOW vessel, less subject to the vertical motions induced by the waves, continues on course more smoothly, while maintaining its speed. And because it uses less fuel to get through the waves, it also helps to save energy
KEY BENEFITS

IMPROVED POWER EFFICIENCY

The bow shape reduces pitch/heave accelerations and speed loss in waves, which renders higher transit speed or reduced power consumption possible. This improves fuel efficiency and reduces emissions to air.
INCREASED COMFORT

The bow shape eliminates slamming and bow impact, thereby reducing noise and vibration. This leads to a more comfortable workplace and more effective rest time for the crew.
SAFETY & LESS DAMAGE

The bow shape gives a soft entry in waves, thus reducing spray and icing. The likelihood of extreme weather damage to the forebody is reduced.

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Old 08-03-2016, 02:58   #48
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pirate Re: The sexiest Catamaran ever?

Quote:
Originally Posted by Delancey View Post
From Ulstein's website (but what do they know, they only make workboats for use in the North Sea)-

The X-BOW hull line design is one of ULSTEIN's main contributions to maritime history. X-BOW vessels are being built at shipyards on many continents. Currently, more than 100 vessels with this bow concept are being constructed or in operational work around the world.

The X-BOW introduces the gentle displacer; a tapered fore ship shape with a different volume distribution as well as sectional angles, resulting in a wave piercing effect at small wave heights, and also reduces pitching and bow impact loads in bigger seas. When comparing fore ship volumes with more conventional, bulbous bow shapes, the X-BOW has more displacement volume starting from the waterline.

The experience is quite amazing. I cannot imagine myself ever travelling with a conventional bow vessel again in winter time.
Captain of the AHTS 'Bourbon Orca​'

While a traditional bow vessel rises on the waves and then drops violently onto the surface of the water, an X-BOW vessel, less subject to the vertical motions induced by the waves, continues on course more smoothly, while maintaining its speed. And because it uses less fuel to get through the waves, it also helps to save energy
KEY BENEFITS

IMPROVED POWER EFFICIENCY

The bow shape reduces pitch/heave accelerations and speed loss in waves, which renders higher transit speed or reduced power consumption possible. This improves fuel efficiency and reduces emissions to air.
INCREASED COMFORT

The bow shape eliminates slamming and bow impact, thereby reducing noise and vibration. This leads to a more comfortable workplace and more effective rest time for the crew.
SAFETY & LESS DAMAGE

The bow shape gives a soft entry in waves, thus reducing spray and icing. The likelihood of extreme weather damage to the forebody is reduced.

Be interesting to see the underwater profile on that ship.. from what little that's visible the reverse starts at the maximum load line and the bow is arched back to bridgedeck height so the sea's wash up and disperse rather than get cut and deflected by the 'traditional' bow.
Now this is all very well in a mono with an engine and the ability to keep to constant speeds for set conditions.. however a sailing catamaran or mono) is a different animal.. subject to many more variables.. so sorry.. I do not see this as proving anything..
Re the canoes.. reckon that's more to do with the waters they operate in 'ice' than sea going ability..
Factor.. many thanks for accepting me (finally) in all my Hermophroditedness..
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Old 08-03-2016, 03:25   #49
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Re: The sexiest Catamaran ever?

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Originally Posted by boatman61 View Post

Factor.. many thanks for accepting me (finally) in all my Hermophroditedness..
I KNEW there was something....

Thats not sexy...

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Old 08-03-2016, 03:56   #50
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Re: The sexiest Catamaran ever?

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Originally Posted by Celestialsailor View Post
Sorry Lads...This is sexy. Not those bars of soap in the water...
Post reported to mods as trolling.
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Old 08-03-2016, 04:07   #51
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Re: The sexiest Catamaran ever?

Everyone has their own tastes, what makes the world an interesting place to explore.

I do find humor/irony in the fact that inverted bows seem to be no more readily accepted than catamarans themselves despite being very ancient technology and in spite of their obvious benefits. Sailors are a funny lot. Some would say stubborn. Some say superstitious. I say biased and prejudiced.

I don't recall the source offhand but some university did tank testing and proved the improved performance and sea keeping of the bifurcated bow on the Aleutian kayaks. It's a fact that they have superior speed and wave handling capabilities.

Shouldn't come as a surprise that native peoples should figure this out long long before we westerners come to our senses. No more so than that ancient Polynesians should figure out that two hulls are better than one if you are partial to speed and stability.

And yet here some of us are, hundred years on in the modern age, unable to accept things because they're different or don't look right to their biased eye. The surest path to maintaining the status quo is to keep on keeping on. Nothing could be less progressive than doing the same old thing.
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Old 08-03-2016, 04:15   #52
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Re: The sexiest Catamaran ever?

Ha! Just remembered this one. Once again tip-o-the-hat to native peoples.

Anyone who has doubts about the sea keeping abilities of inverted bows has probably never been whitewater canoeing before. Native Americans were shooting rapids in canoes like this long before Columbus was born.

Aesthetically speaking, I don't know if I could imagine a more beautiful form. Someone gonna tell me this boat looks UGLY? Really? Like a cheap car?
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Old 08-03-2016, 04:45   #53
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pirate Re: The sexiest Catamaran ever?

And the Welsh were using these in the Irish sea before the Indian canoe..
Make for a stable cat methinks..
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Old 08-03-2016, 04:58   #54
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Re: The sexiest Catamaran ever?

I'm with Factor and Uncivilized on 'reverse', or 'inverted' or 'wave-piercing' bows on cruising boats. And Delancey, your clip is illustrative because it does not show an inverted bow at all, but rather a hybrid bow that overcomes the failings of these designs in the real world.

As Bob Perry pointed out, some forward overhang is important on a cruising boat in order to reduce water on deck and to avoid turning the boat 'into a submarine'. Even assuming that cats with reverse bows are longer than their counterparts - and IMO this is not a safe assumption (e.g., is an Alpha 42 actually a 38 foot cat with a more efficient bow?), there is still a lack of reserve bouyancy referred to by Unciviized. This can get the unwary into some serious difficulties.

Indeed, if a reverse bow was a win/win situation, then the ideal bow/hull shape would be a door-stop like wedge. The 'x-bow' shown in Delancey's video is a design that compensates for the failings of a reverse bow by providing substantial reserve bouyancy in extremis, as well as spray/green water diversion off the deck. How? By having a traditional bow with overhang as well as a 'wave-piercing' segment largely below the waterline.

To paraphrase Bob Perry, sometimes traditional elements in yacht design are traditional because they work!

Brad
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Old 08-03-2016, 05:02   #55
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Re: The sexiest Catamaran ever?

I've seen basket boats from Vietnam before but never the Irish ones. Cool! The perfect vessel for those who cannot make up their minds about what course to steer!
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Old 08-03-2016, 05:31   #56
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Re: The sexiest Catamaran ever?

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its taken to post 40 to have a monohuller come in to the multihull forum and and tell us why we are wrong. Nearly a record for this place.
Na, look back. Post #9 and especially #11. About par, I'd say

The Polynesians colonized the Pacific on multihulls. http://pvs.kcc.hawaii.edu/ike/moolel...ettlement.html

ol' Nat Herreshoff, whose boat AMARYLLIS is pictured above #51, thought well of multihulls. "think twice ere they venture to 'Sport with Amaryllis in the shade.'"
http://www.runningtideyachts.com/mul...Amaryllis.html
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Old 08-03-2016, 05:55   #57
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Re: The sexiest Catamaran ever?

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Ahh.. the Infamous reverse bow.. so effective that since early last century was abandoned by so many.. and today.. abandoned at sea..
I prefer more positive buoyancy up front myself.. and.. beauty as ever is in the eye of the beholder.. Kardashians for the masses..
Audrey Hepburn for the tasteful..
Boat man.....


There are a couple ways to achieve a reverse bow.

One is to remove material at the deck, reducing buoyancy, as you are thinking.

Amother way is to fill in the triangle below the water line and forward of the original bow,*adding* significant buoyancy.

My cat has reverse bows that are added buoyancy compared to your picture.

A lot of people get confused thinking the overhang was taken away.

On a proper design, a lot of initia buoyancy is ADDED to the original design.
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Old 08-03-2016, 06:06   #58
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Re: The sexiest Catamaran ever?

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Be interesting to see the underwater profile on that ship.. from what little that's visible the reverse starts at the maximum load line and the bow is arched back to bridgedeck height so the sea's wash up and disperse rather than get cut and deflected by the 'traditional' bow.

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Old 08-03-2016, 06:15   #59
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Re: The sexiest Catamaran ever?

Traditionalists give up their narrow minding outlook in thinking flare is the only way to achieve reserve buoyancy. There is more than one way to skin a cat. Adding height as in the Briand cat, X-bow, American canoe is another viable approach. Even the Vikings figured that out, not much flare on the bow of a longboat, infact some were inverted!
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Old 08-03-2016, 06:30   #60
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Re: The sexiest Catamaran ever?

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Originally Posted by s/v Jedi View Post
They range from this:


to cats classy like this:


and I bet some find the first one sexier
I thought the first one was a theme park...no?
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