Wave Piercing Bows

Discussion in 'Multihulls' started by CatBuilder, Apr 15, 2012.

  1. CatBuilder

    CatBuilder Previous Member

    [​IMG]

    Wave piercing bows appear to be all the rage today, from the fastest America's Cup catamarans to the newest destroyer built by the US Navy.

    Does anyone else find them ugly to look at compared to a plumb bow?

    Do the majority of people find them attractive from a styling point of view?

    Lastly, they throw more spray up, correct? Say I were to cave into fashion and finish my bows with the reverse angle on them such as found on this boat...

    [​IMG]

    Would I end up with unbearable spray in my forward cockpit (located just aft of the mast in both of these pictures and in my boat) compared to a normal, plumb bow such as this?

    [​IMG]

    Would there be any more tendency for the bows to stuff since they are cutting into the wave instead of riding up over it?
     
  2. Doug Lord
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    Doug Lord Flight Ready

    Reverse bow

    I like the looks of it and have used it on sketches for 15 years. For a given length of boat such a bow gives the maximum waterline length with a smaller deck length and therefore less weight allup and less weight in the forward end of the boat. I've read that it is credited with reducing pitching in the A Class cats.
    But ,again, I really like the looks of most versions I've seen.

    An older thread on the same subject: http://www.boatdesign.net/forums/sailboats/wave-piercing-pitching-damping-marketing-18037.html
     
  3. Corley
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    Corley epoxy coated

    I dont find them ugly, aesthetics is a constantly moving target afterall. There are plenty of sailors who in the past disliked the look of plumb bows as well versus the overhanging bow. There are different degrees of reverse bow too in terms of their extremity. Kurt drew me a set for my Formula 40 trimaran project they look good. I think though for something to look good as well as being functional it needs to be drawn as an integrated part of the design so other styling cues dont make it look "uncomfortable".
     
  4. cavalier mk2
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    cavalier mk2 Senior Member

    It isn't their looks that bother me but the potential for damage cruising. I'm not a fan of plumb stems for the same reason. Riding over drift lengthens the moment of impact reducing damage significantly so I advocate traditional overhangs for cruising. Reducing spray is also a good thing. They sort of remind me of a Studebaker for some reason.
     
  5. groper
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    groper Senior Member

    i like em... aesthetic taste varies with the individual obviously, if you like em CB then go for it i say...

    As for the spray, i have noticed that regardless of the profile whether its plumb, forward rake or aft rake, the fineness or sharpness of the front edge determines the amount of spray thrown. If the front edge is blunt, it throws spray everywhere. If the front edge is very sharp, spray is minimal...

    You can visualize this by dragging a knife thru the water by hand - no water is pushed up the blade.
    Do the same with a peice of dowel, and youll see water pushed up the dowel by the water pressure in front of the dowel, this is where the wind can get a hold of it and blow it everywhere...

    Blunt and plumb bow on the sprited 38 = spray;
    [​IMG]

    Sharp and plumb bow on the SIG45 = less spray;
    [​IMG]
     
  6. Corley
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    Corley epoxy coated

    One of our club members has a Chris White Atlantic 42 catamaran with plumb bows it also has a front cockpit. When the seastate gets up a bit it's just about untenable without a snorkel so it's not just a plumb bow/reverse bow issue.
     
  7. PAR
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    PAR Yacht Designer/Builder

    We'll soon see if it lasts as long as water ballast and wings on keels.
     
  8. BobBill
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    BobBill Senior Member

    Wavecutter Bow Stems

    I was a skeptic until I watched two cats sailing with cutters...one was an AC45 the other was a cruising cat. The wave cutters, as you know, reduce the hobby horse effect that reduces straight line progress. And, as you know, they are primarily cats...the pic below shows one variation I like that combines concepts and seems to reduce the spray problem


    Still, I have to agree with Par, as I always do, it remains to be seen, if they are worth the trouble and expense and so on.

    I have often wondered what Rod Mac Alpine-Downey would have thought about the dreadnought bows so trendy today. He was pretty good cat designer.

    And I also wonder, why they do not appear on the proas and cats the Polynesians have been sailing for centuries?

    Also, as we all know, spray can be dampened a bit (yes, I know) using properly placed rails.

    I am building (model and lofting stage) a modified Malibu Outrigger and have considered the wave piercing bows for both hulls, but still working on spray issue and spar/sail type (Cat versus original semi-crab claw, which seems the best choice.

    Boat will likely never be surf-launched but Lake Michigan and the Gulf do produce some nasty chop etc.

    One cannot deny Nice Pair's bows do look good and seem to do the job.
     

    Attached Files:

  9. souljour2000
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    souljour2000 Senior Member

    Par...et al...It's fairly obvious that reverse rake bows are a fad...but am curious what your opinion is of plumb bows....isn't at bit least a bit of traditional overhang (and accompanying reserve bouyancy almost always desirable..I've gotten to where I don't even like plumb bows...much less the bow-shapes shown in above photos...(maybe I am turning into an old fart...but I am 44...:(). I am aware that plumb bows have been around since at least the early steamship era/great white fleet,etc...so they must have some merit... despite the lack of reserve boutancy....but reverse overhang seems absurd frankly...though nice to look at somewhat...
     
  10. BobBill
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    BobBill Senior Member

    Wavecutter Bow Stems

    Had this clip also.
     

    Attached Files:

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  11. keysdisease
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    keysdisease Senior Member

    Does anyone else find them ugly to look at compared to a plumb bow?

    Like Corley said, "aesthetics is a constantly moving target afterall"

    When I first saw a plumb bow I thought it was butt ugly. I guess my mind just couldn't get wrapped around something so different from what I considered at the time what a bow should look like. Now I can appreciate the aesthetics of the plumb bow and I consider then pleasing to my eye.

    To me, the "wave piercing bows" are more visually pleasing than the plumb bow was when I first saw them. I think this may be because they look fast even standing still, where plumb bows just don't.

    Steve
     
  12. Corley
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    Corley epoxy coated

    In performance applications it's not just about reserve buoyancy when the bow buries. If you drive a conventional style plumb or overhanging bow into the rear of a wave it can have more tendency to get "stuck under" the wave and cause significant drag. This can slow the boat dramatically and increase the possibility of a pitchpole. The reverse bow which does still have considerable reserve buoyancy is a way of balancing the boat without increasing drag rapidly when the bow immerses. On race boats this really matters on cruising boats it might help in certain situations the boats shown in the pictures are all race or performance oriented cruising designs.

    I also fail to see how a reverse bow adds "trouble and expense" to a build or in maintenance terms in most composite builds the reverse bow is a sacrificial foam or composite block glued to the front of the boat.
     
  13. BobBill
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    BobBill Senior Member

    Dreadnought Bow Stems

    Good point, Corely. I was thinking changing my plans in terms of added expense etc. Adding that "bow block" is often forgotten in the conversations.
     
  14. DCockey
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    DCockey Senior Member

    After watching some of the AC World Series with the boats tending to bury a bow when jibing and sometime go over, I wondered if they would benefit from additional "secondary" buoyancy in the bow.
     

  15. Doug Lord
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    Doug Lord Flight Ready

    ================
    I don't think so but I'd bet they would benefit from more beam and curved lifting daggerboards. The beach cats using curved lifting daggerboards report a dramatic decrease in the incidence of pitch pole-rudder "L" foils as on the A Class cat "Mayfly" might also be beneficial.
     
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