Reverse bows on cruising cats pros and cons

Discussion in 'Multihulls' started by DennisRB, Mar 1, 2013.

  1. DennisRB
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    DennisRB Senior Member

    Eric Spoonberg (who you probably all know is a regular poster here) designed a plumb bow conversion to Freedom 36. I have to say this is pretty cool!

    http://www.sponbergyachtdesign.com/Wobegonbow.htm

    [​IMG]
     
  2. jamez
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    jamez Senior Member

    Thanks for that, but I should have been more specific - I meant a multihull example. I'm interested in whether there are any tangible results with these mods with respect to bow burying which is less of an issue for a keelboat.
     
  3. DennisRB
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    DennisRB Senior Member

    Sure, a conversion on a multi would be a better example to have. But I thought this might be interesting anyway

    My possibly incorrect assumptions are: I would expect that with the mod done to a cat, there would be less tendency to bury under the same conditions, however, as the point of burying approaches, it will happen faster. So possibly, the boat will be sailed harder which might therefore actually increase pitchpoling. This would apply to race boats being pushed to the limit. The extra total buoyancy would raise the limit, but reduce the safety margin of "reserve buoyancy" at the point where the boat looks like it is close to burying the bows. When cruising you wouldn't be pushing the limit, so overall it would be safer. But then again its good to have ample warning you are pushing it.
     
  4. catsketcher
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    catsketcher Senior Member

    Reverse bows came of age in A class cats. In A class the foredeck ( the area in front of main beam) takes up over half the length of the boat. Those people who sail beach cats or high performance tris will already understand the need for wave piercing bows on tri floats or beach cat bows. It is not safe design to have the drag increase greatly as the bow digs in.

    I asked a question on multihull longitudinal stability to Nigel Irens when I did an article on B and Q and also Sodiebo. His take on it was that you couldn't make a boat more stable just by adding volume up front as this may increase tripping moment at the wrong time - just as the bow goes under. So good tris have water shedding decks as do good beach cats. Irens , like Richard, is very keen on the Tornado, even though its decks are no where near as rounded as other beach cats.

    What really gets my goat about the designers using reverse bows is that it is all bunkum on a cruising cat. The reason you have wave shedding bows is to ensure as little increase in drag as you drive the boat hard and push one bow under. Look at the A class - as the leeward bow goes under there is NO extraneous stuff on the bow - apart from a single forestay wire.

    Then have a look at the reverse bows on the Catana or any other cruiser. If the bow ever gets pushed under then almost at the same time the netting, forebeam, cleats and any other deck hardware increase drag hugely. It's like taping your ears back to go faster - the effect of the other parts of the cruiser bows will mean it has no impact.

    Now all of this would be okay if the designers weren't contorting shapes to get the new style bow but any builder knows that a designer doesn't even have to draw the bow profile. All you have to do is draw the section shape within 500mm of the bow and the bow will take care of itself.

    Flared hull sides give raked bows - ala IOR yachts. Straight topsides give plumb bows - modern racers. I built the hulls for a tri and the famous designer didn;t even give me bow profile - it didn't matter. To get reverse bows you must have sloped in topsides - now why would you do this on a cruiser? To get less interior room? Smaller deck area? More water on deck? More sunlight into the windows? Make it even harder to work the boat in the marina?

    I like these bows on A class cats and other beach cats. They make sense on wave piercing tri floats and some main hulls but they really are an affectation. In a marina I have often walked one bow around a pile and then jumped on deck. On my trailer cat I hold the deck cleat and walk the hull onto the trailer around the trailer post.

    Design features should be a result of solid need and rigorous thinking - not fashion. These bows on cruisers are speed stripes that make the boat harder to build and less useful in close quarters. If for some reason your cat ends up ( for very good reasons) having inward sloping topsides you will get reverse bows. Otherwise let your bows be the shape your hull dictates.

    Rant over

    Cheers

    Phil
     

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  5. Ilan Voyager
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    Ilan Voyager Senior Member

    Catsketcher, nice and clear post; fashion is unhappily the goal of a lot of boat designs, look at some motor boats. The Catana is ridiculous, talking of performance about a floating condo...I remember the fashion of bulbous bows on monohulls a long time ago.
     
  6. Richard Woods
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    Richard Woods Woods Designs

    One other major factor you should ask the builder/designer before buying a reverse bow moulded grp boat is how they actually make the hull.

    It certainly won't be a one piece moulding, as it could be with a conventional flared hull and overhanging bow. There are ways to do it using split moulds and flanges or even a separate endcap but in any event you will have several joints in the narrowest most prone to damage part of the boat

    I have seen several large, French built catamarans that have split their bows, and they weren't even reverse bows

    Richard Woods
     
  7. tomas
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    tomas Senior Member

    Both of you are correct of course and as a new-comer to all things nautical it would be silly for me to take issue with this but I would pose the following questions:

    If a new "fashion" trend comes along that customers respond to so that more boat-builders stay in business, skilled laborers are kept working. suppliers and OEM's can maintain/increase production etc, shouldn't you ultimately support it?

    If the new AC72 class brings in new people to support sailing, even though it breaks from the traditional mono-hull tradition, isn't it a good thing overall?

    If people are excited about increasingly lighter and "exotic" canting-keel global racers that big $ponsor$ support, isn't that a good thing?

    If GM can sell more Cadillac Escalades because customers decide that they like they way they look with low-profile tires, silly though it may be, doesn't that support economic growth?
     

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  8. rberrey
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    rberrey Senior Member

    That would depend on the boat, depends on whether it compromises the funtion, purpose or safety of the boat. I cant see Richard Wood designing a boat placing looks over any of the above. I am almost sure Richard designs boats for money, I am also almost sure he could make more money by doing what the above post sugests. I am sure by reading his post on different sites that there are other reasons he designs boats other than money. Agree or not agree his advice is always based on vast experience and love of sailing.
     
  9. michael pierzga
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    michael pierzga Senior Member


    Clients dont know anything about boats. They think they know because they read magazines and fall victim to marketing hype.

    Boats arent cars. Boats are very expensive to purchase , maintain, are constructed to achieve a 25 or 30 year service life and must be designed for a purpose. Form and function, not eye candy.
    .
    The style trend transferred from the racing yachts ... long waterline, narrow entry, light displacement, box shaped boats, is unfortunate.

    Highly stylized, high maintenance, difficult to use boats loose resale value fast. The client wastes so much money that they never purchase another boat again. Not good for the marine industry
     
  10. tomas
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    tomas Senior Member

    My post is not directed at Richard Woods in any way so I don't know you wrote this. I suggest that you re-read my post.

    My post was about trends that consumers respond to that push product design in directions that knowledgeable professionals would not normally propose themselves, such as Richard for example.
     
  11. Gary Baigent
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    Gary Baigent Senior Member

    Why so snotty nosed about this "new" trend in bow shapes?
    Actually they are not new at all but near two Centuries old.
    So they're traditional on a number of designs like:
    New Haven Sharpies (plumb and raked forward bows) Bristol Channel pilot boats (plumb), oyster dredging 40 foot decked skiffs (some raked forward) Sandbaggers (Truant and Comet's raked forward) US shallop and gill net boats (plumb), some of the early NZ Logans with their ram bows and many others.
    Also on modern multihull cruising designs like the Catana, looks cool to me, nothing wrong with full length waterlines.
    Also there was nothing wrong with Lock Crowther's bulb bowed cats either, was an attempt to smooth the ride, reduce pitching, sort of a forerunner to the "modern" forward raked bows.
     
  12. michael pierzga
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    michael pierzga Senior Member

    Its a trend...like long Jboat overhangs.....change the rating rule and its gone.

    Modern boats have gotten so bad that they must hang junk like anchor rollers off the bow of the boat...the stem is so narrow that they must put the roller furl drum below deck in order to accomodate a bow pulpit.. The displacement of modern boats has gotten so light that in order to achieve headroom the topsides grow way too high and the bilge is gone. Square boxs with masts. Any machinery that must be located below the floorboards, in the missing bilge, lives a hellish life. Typical lightweight 50 footers have to pump thier poo poo and grey water UPHILL into tanks. Water in the bilge ends up sloshing up the topsides. Storage under bunk turns into tanks.

    Skip the goofy style trends and instruct your NA to pursue pure form and function only. If its a race boat...go for it.
    If its a dual purpose boat skip the trends... Many clients wont be fooled by marketing hype.
     
  13. rberrey
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    rberrey Senior Member

    Sorry Tomas, I only ment to use Richard as an example of a good designer. I am sure there are boats that can be designed with reverse bows and other new or old design features without compromising a good design. My point is a good designer would not or should not compromise for a dollar.
     
  14. Alex.A
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    Alex.A Senior Member

    The designer would want his name and reputation to outlive the ( fashion ) trend ?
    Short term gain wouldn't be worth a long term loss.
    The customer isn't always right.
     

  15. Submarine Tom

    Submarine Tom Previous Member

    The trick, I believe, is getting the customer to perceive they are getting what they think they want without compromising your integrity.

    It's a fine balance, no?

    The customer must perceive they are right...
     
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