Reverse Bows

Discussion in 'Boat Design' started by quicksail, Mar 30, 2005.

  1. quicksail
    Joined: Jul 2001
    Posts: 58
    Likes: 1, Points: 0, Legacy Rep: 25
    Location: canada

    quicksail Junior Member

    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???
     

    Attached Files:

  2. Willallison
    Joined: Oct 2001
    Posts: 3,590
    Likes: 130, Points: 0, Legacy Rep: 2369
    Location: Australia

    Willallison Senior Member

    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.
     
  3. jehardiman
    Joined: Aug 2004
    Posts: 3,101
    Likes: 597, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    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.
     
    Last edited: Mar 30, 2005
  4. Willallison
    Joined: Oct 2001
    Posts: 3,590
    Likes: 130, Points: 0, Legacy Rep: 2369
    Location: Australia

    Willallison Senior Member

    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
     
  5. Skippy
    Joined: Nov 2004
    Posts: 568
    Likes: 1, Points: 0, Legacy Rep: 12
    Location: cornfields

    Skippy Senior Member

    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.
     
  6. Doug Lord

    Doug Lord Guest

    Bethwaite/Billoch

    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.
     
    Last edited by a moderator: Mar 30, 2005
  7. Willallison
    Joined: Oct 2001
    Posts: 3,590
    Likes: 130, Points: 0, Legacy Rep: 2369
    Location: Australia

    Willallison Senior Member

    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
     
  8. Doug Lord

    Doug Lord Guest

    url

    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...
     
  9. yipster
    Joined: Oct 2002
    Posts: 3,486
    Likes: 96, Points: 58, Legacy Rep: 1148
    Location: netherlands

    yipster designer

    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?
     
  10. dionysis
    Joined: Jan 2003
    Posts: 258
    Likes: 3, Points: 0, Legacy Rep: 44
    Location: Tasmania, Australia

    dionysis Senior Member

    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.
     
  11. quicksail
    Joined: Jul 2001
    Posts: 58
    Likes: 1, Points: 0, Legacy Rep: 25
    Location: canada

    quicksail Junior Member

    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?
     
  12. dionysis
    Joined: Jan 2003
    Posts: 258
    Likes: 3, Points: 0, Legacy Rep: 44
    Location: Tasmania, Australia

    dionysis Senior Member

    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.
     
  13. water addict
    Joined: Jun 2004
    Posts: 317
    Likes: 6, Points: 0, Legacy Rep: 73
    Location: maryland

    water addict Naval Architect

    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...
     
  14. Olav
    Joined: Dec 2003
    Posts: 329
    Likes: 47, Points: 38, Legacy Rep: 460
    Location: Filia pulchra Lubecæ

    Olav naval architect

    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.
     

  15. Willallison
    Joined: Oct 2001
    Posts: 3,590
    Likes: 130, Points: 0, Legacy Rep: 2369
    Location: Australia

    Willallison Senior Member

    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...
     

    Attached Files:

Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.