Reverse Bows

[quicksail]

I was just wondering what people think of the reverse bow. Seems like a regression back to pre WWII gun boats and such. I would also imagine they could be very wet in the right conditions. Do you think the wave piercing effect is that much of an advantage? Is this the future of yacht/ship design? comments, quiries, opinions???

[Willallison]

Personally I love plumb bows, but that's just a personal aesthetics thing.... not so keen on those reverse bows though.
Whilst a reverse bow increases the waterline length, it also means that the vessel suffers from reduced boyancy as the bow plunges into a wave. Thumbs down from me.

[jehardiman]

It is not that it suffers from reduced buoyancy, as a matter of fact buoyancy increases just like a flare bow just not as much. The advantage is to reduce the waterplane area growth which reduces the rapid growth in buoyancy forward which is important in reducing pitch response. Less waterplane area, less un-needed buoyancy forward, less pitch motion, smoother ride. Or so the theory goes.

[Willallison]

You're right of course - wrong choice of words on my part - I should have said reduced rate of boyancy increase.
I see the theory behind what you're saying too, and I guess that as long as there's sufficient bouyancy to bring the bow back, then it would all work - still reckon it's ugly though! :p

[Skippy]

I don't mind the looks. It just seems like the buoyancy increase will be puny, and the bow will tend to toe itself in more.

[Doug Lord]

Martin Billoch and Julian Bethwaite have a couple of designs that are absolutely breathtakingly gorgeus using a reverse bow; I think it was their 40 footer I saw on their site a couple of weeks ago. Now I can get to the site but can't see anything! I'll post the url in case any of you have better luck!
http://www.billoch.com
It was simply the best treatment of this kind of bow I have ever seen though I like it on the A cats as well...
Juan K has designed two Volvo 70's with a much less impressive use of the reverse bow..
I think that anyone sailing against such a bow in close racing should take the words "keep clear!" to heart because first contact is likely to be at the waterline.....
Be that as it may I think this kind of bow has a bright future in sailboat design.

[Willallison]

Doug,
The link you posted took me to a telecommunications company.... :confused:

I too have seen a couple of rather elegant yachts - both sail and power that incorporate reverse bows - though their's were far less pronounced than those shown above

[Doug Lord]

Will, it's corrected but I still can't see anything when I get to the site. I'd be interested to know if you can...

[yipster]

interesting concept.
http://www.billoch.com opens ok here but cant find much in a jiffy.
wonder bout the underwater lines of these reversed bows, with a bulb?

[dionysis]

I may be wrong, but it seems to me that the reverse bow is usefull in a light displacement boat. A heavy boat, as long as it is not too short, can carry flare forward. It has the momentum and weight. A light boat on the other hand needs a way to slice into waves. Light boats get stopped by flare forward much easier.

[quicksail]

Some pics of other reverse bow concepts would be nice. I like the look but question the performance. In many cases would it not be easier to go with just a plumb bow? I have tried to do some reverse bow designs but it is hard to make them look good in terms of fairness and shape. I found the body plan extermely hard to do. That is why I can appreciate these designs when done well. Keep the comments coming! Is this where yacht design is heading?

[dionysis]

I must admit though, that the "full" reverse bow, that is, a bow that reverses from the waterline back and up, does not look like a pretty shape.

I think a "semi" reverse looks much better. This is where, from side elevation, the bow rises in a fair line from the stem as in a spoon bow, but then reverses half way up and meets the deck line vertically above the forward waterline perpendicular. Somewaht like an ellipse. I hope you got the picture.

I think you will first see the reverse kind on the modern racing multihulls.

[water addict]

You are all probably familiar with wave-piercing cats, ie goldcoastyachts.com and incat.
Monohulls - you lose a lot of interior volume for a given ship length, wetter ride, seakeeping issues in following sea. Reduced pitch response, can have smaller radar cross section, if you are into stealth...

[Olav]

Wavepiercing bows are quite common with skiff Moths (although very few have an aft raked stem though). A lot of today's Moth designs including my own versions feature a more or less large amount of tumblehome at the bow which - as said before - reduces the waterplane fwd a lot and helps the boat going through the wave. My experience is when sailing upwind in chop the boat will just go effortless straight ahead with almost no pitching motion which is very comfortable and makes the rig far more efficient.

[Willallison]

The wavepiercers that I've seen - I was onboard Incat 050 only yesterday - only sort-of incorporate a reverse bow. The hulls are really just of normal form, with eliptical sections and are of course very narrow. It's only the bit that connects them to the main (centre) hull that slope backwards like a reverse bow. (what do you call those connecting bits anyway? :confused: ) I guess you could argue that this forms part of the bow...

[yipster]

http://www.kids-and-trips.nl/uploads/RTEmagicC_hoverspeed.jpg.jpg
hooverspeed has something the same since some years.
i can find booking, hotels and car rent but this is the only picture?
thats what boatdesign means to the world i guess :mad:

[Willallison]

Yipster,
The Hoverspeed boats are built by Incat here in Tassie. Go to www.incat.com.au for more pics..

[lucdekeyser]

Beauty is in the eye of the beholder. To my eye, reverse bowed Kvaener's "Super Liner 300", pictured below on http://foxxaero.homestead.com/indrad_038.html sure's got it.

Luc

[Thunderhead19]

Not pretty? We disagree.

http://www.sms-navy.com/SMS_Baden-ptbow-top.jpg

[Oyvind]

Dear Sirs!

Glad to see that You all have opinions on reversed bows! The picture on the top, the red boat, is actually called ULSTEIN AX0X and was designed by me back in June 2003 (I work at ULSTEIN DESIGN in Norway, doing hulldesign and overall design). It is an Anchorhandling Tug Supply Vessel using diesel-electric propulsion. It has been an idea of mine since 1997 to use these bows commercially, and this boat represents a vision.

This week we actually launced a building contract for a boat using a reversed bow! It is called ULSTEIN AX104, and is somewhat different from the earlier mentioned boat. Check out http://www.ulsteindesign.com! We've tested it throroughly, and to You sceptics out there; it works like nothing else! It is not a wave piercer, but works more like a dolphin! I'm introducing a new volume distribution, different from what most people think, and we found lower speed loss in waves, lower heave and pitch accelerations, NO slamming, NO green water on bridge deck etc. We call the bow X-bow, patent pending. This boat also have diesel-electric propulsion using azimuthing thrusters, and also have a new safe anchorhandling system - SAHS, patent pending.

It's been a busy couple of years!

Br
Oyvind

[quicksail]

Thanks for your reply Oyvind. I hope you don't mind me posting your design. I was just very intrigued by your design along with other designs with reverse bows. It is a definite shift in design philosophy and is very striking to say the least. I am interested in the development of these designs and the benefits gained. Thanks for filling me in on some of the possible benefits.

I was wondering though, how you can patent something that aready exists. I find patenting things like CBTF and reverse bows very hard to do as many versions already exist from the past and present. I understand that there is a lot of detail not mentioned. These sorts of patents can't be generalized, they must focus on specific design features. Anyway thanks for your insight and I look forward to seeing your ship launched. It may be the start of a new design trend. Who knows.

[cyclops]

Reverse curve bows are very efficient at reducing the bow wave. Most all new with it ship designs have a subsurface bow bulb to reduce bow drag. High speed, + 40 knot, Catamaran ferries are equipped with them. If the "new" marine designers come up with more new hull improvements, they will have to pay royalites to the dead. Even the "new" Q E 2 has a massive bow bulb and makes almost no wake at any speed. ------------------------------------------------The only real possible negative would be lifting the bow fast enough in a strong storm at sea? I have never seen side by side data of the same ship run with each type of bow in storm conditions. Maybe USN carrier design has a set?

[brian eiland]

This VSV hull technolgy makes use of reverse bows, http://www.vsvboats.com/
in looking at some of the photos in operation, the bow disturbance wave appears minimal


...and then this catamaran's ugly reverse bows (in my opinion, of course I'm not a big fan of the over-utilized plum bows on cruising designs either)

1) http://www.victorinox.com/newsite/en/action/actiondetails/katamaran.htm
2) http://www.kkg.at/de/93/

[Rasman]

My observation is based on logic rather than formulas etc, but I can imagine a boat of this design could travel into a large swell and experience very little motion. My reducing the rate of bouyancy gain, you would inevitably reduce the bounce effect. Any other hull would jump off a wave, I beleive a hull like this would dive into a wave and come out the other side with minimal effect on ride comfort. Not sure about efficiency etc... Cant imagine it would be particularly beneficial to efficiency.

[marshmat]

Back in the mid-nineties Kvaerner Masa-Yards was working on a 225-metre Ro-Ro freighter concept that had the most radical reverse bow I've ever seen... http://www.masa-yards.fi/ but I can't seem to find that particular design anywhere.

The wave-piercing designs, which usually incorproate a reverse bow to some degree, run faster with less pounding and heaving than a regular hull. Some claim that a monohull like the red one above, or the RoRo225, with a reverse bow extending all the way to the bridge, is more seaworthy than a conventional bow (if you stuff the bow into a huge wave, the boat cuts through it rather than taking on water). But for most applications the tradeoff in reduced deck space and hull volume isn't worth the higher efficiency and whatever unknown seakeeping abilities it may give.

[SailDesign]

Oyvind,
Congrats on getting your ugly mug on the front cover of Maritime Reporter! Almost life size, too.
Steve

PS - nice bow.... :)

[oldsailor7]

Look at a picture of IDEC or SODEBO.

[charmc]

Interesting reverse bow megayacht by Feadship:

During the launch ceremony at the Koninklijke De Vries yard in Aalsmeer (NL) on 5 January 2008, all eyes were on Predator’s sensational reverse bow. This bow forms part of the aggressive new styling brief at the core of the client’s wish-list. “The owner arrived at the yard in late 2004 with a request that we partner on something different than anything else afloat,” comments Henk de Vries. “Together with De Voogt Naval Architects and Bannenberg Designs (interior), we have created a super-sleek and highly sophisticated yacht that is genuinely innovative.”

http://www.yachtforums.com/forums/yacht-news-builds-launches/8670-new-launch-feadship-72m-reverse-bow-predator.html

[charmc]

"By sweeping the bow backwards from the waterline, up… an oncoming wave encounters less resistance in contrast to a conventional forward-flaired bow. Essentially, an oncoming wave washes over the top of the deck and dissipates, as opposed to being displaced outward by a conventional bow." from discussion of Blohm & Voss's Sigma, an even more radical design, whose reverse bow's visual impact is matched by a unique superstructure.

http://www.yachtforums.com/forums/yacht-news-builds-launches/8672-new-launch-blohm-voss-118-meter-sigma.html

[charmc]

Still another reverse bow megayacht, this one from Lurssen, designed by Igor Lobanov:

http://www.superyachttimes.com/editorial/5/article/id/1102

Why these radical designs? Well, it seems that boredom is setting in among the super rich. In fact, according to Mr Lobanov, "No longer is a 130m yacht so unusual or so impressive." :D :D

[KP Texan]

The new DDX has a reverse bow design so I'm sure there is some merit to it.

The reason I'm posting is to ask about the Ulstein X-Bow design, and I was interested to find that the original designer had actually posted in this very thread! My company is looking into the construction of a 100+ meter Multi Purpose Support Vessel and I have been chosen to head up the engineering side of things. Among other designs, we are considering the Ulstein X-bow and I was curious about the performance of this design. Now that the design has been out for several years, I'm sure that some of you have heard things about these vessels and was looking for some input on its use for our application.

Thanks so much,

Wes

P.S. I'm absolutely blown away by the knowledge on this board and have discovered that I have much to learn!

[brian eiland]

The new DDX has a reverse bow design so I'm sure there is some merit to it.

The reason I'm posting is to ask about the Ulstein X-Bow design, and I was interested to find that the original designer had actually posted in this very thread! My company is looking into the construction of a 100+ meter Multi Purpose Support Vessel and I have been chosen to head up the engineering side of things. Among other designs, we are considering the Ulstein X-bow and I was curious about the performance of this design. Now that the design has been out for several years, I'm sure that some of you have heard things about these vessels and was looking for some input on its use for our application.

Thanks so much,

Wes

P.S. I'm absolutely blown away by the knowledge on this board and have discovered that I have much to learn!
Hello Wes,
Try out the 'search button' in doing some research on a subject.

Also look at "axe bow' for your particular subject matter, and you'll find a few other subject threads.

This was an interesting addition to one of those subject threads:
http://www.hiswasymposium.com/pdf/2006/J.%20Gelling.pdf

[KP Texan]

I believe that the Axe Bow and the Ulstein X-Bow are different concepts (I remember reading about the Damen Axe Bow sometime back). After running a search, this thread seemed to have the most information on the X-Bow type vessels so this is where I posed my question. I'll attempt to search for more threads on the X-Bow.

Thanks so much,

Wes

[decatoire]

olivier decatoirehttp://www.reverse-bow.com/albumphoto2/index.html

[bexman86]

to me this seems like a case where styling has moved to parts of the boat where it should not be. below the rubrail, styling should take a backseat to practicality!

and quicksail - in the two pictures you showed... the left one is a yacht with a reverse bow, however the right one is a supply vessel with an x-bow. while the shape of the x-bow (in profile) is similar to a simple reversed bow shape, the idea is different and the x-bow shows increases in hull efficiency as well as improved seakeeping.

[dskira]

Reverse bow is a nightmare for the anchor chain. You add a bulbe and you are in real huge trouble. (for a yacht of course)