Reverse bows on cruising cats pros and cons

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

  1. catsketcher
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    catsketcher Senior Member

    Vplp

    This is the Tan 66 from VPLP. Now they are obviously good designers so it's a bit like criticizing Einstein to disagree with them. What interests me is that they have a normal flare at the stern regions of the hull but with reverse bows. They may have pulled the flare in at the bows but they also have made the bow very flat at the deck to conform to the profile.

    I don't get this. The whole idea of the reverse bow is to address the large increase in drag as a bow goes under then you have a large slab section that will act as a nice downward acting scoop. Even if sailed normally this is going to be wet.

    cheers

    Phil
     

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  2. Doug Lord
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    Doug Lord Flight Ready

    -------------------
    I like the looks of reverse bows and their function in most cases but I don't get the flat part of the bow on this boat at all. When the water gets there the boat will be really moving and those flat areas would work like dive planes.
     
  3. Ilan Voyager
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    Ilan Voyager Senior Member

    It's a cruising boat not intended to push down its bows under water or it will be a big panic. It's just looks, design. Like the spoilers and the alu rims on a old Volkswagen Golf. VPLP have also to pay the bills.
     
  4. catsketcher
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    catsketcher Senior Member

    Ilan

    For me the spoilers and alloy rims don't detract from the safety of performance of the car. In a swell or large chop these bows will be scooping up water from the leeward bow. If it was only for aesthetics I would understand but this seems to detract from the boat's utility. As we know the leeward hull of a cat always sinks when sailing. The bows also have a higher immersion rate than sterns so every cat hull (canoe sterned hulls excepted) goes bow down when sailed in breeze. These bows will be making the boat less safe and wetter (it may be negligibly so).

    I hope buyers start asking more questions soon.

    I remember an Auusie designer drawing a new cat that was very innovative. After the cat showed many and serious problems the owner got an experienced builder to fix it. Designers must be very careful they don't stiff the buyer too. If VPLP were making this with their own money I would have no problem.

    cheers

    Phil
     
  5. tomas
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    tomas Senior Member

    It's the Escalade with low-profile tires syndrome. In a world-wide down economy, it seems you have to do whatever it takes (within reason) to attract customers, and apparently, enough new customers see this as more appealing.
     
  6. DennisRB
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    DennisRB Senior Member

    Have to say, although I like the style of reverse bows. I value practicality over style. Hence the making of this thread to begin with. I also have to say the 2 cruising cats mentioned in this thread (Catana and VPLP) don't appeal to me.

    Catscketcher could you share the name of the Aussie designer with the serious probs? PM me if you don't want to mention it publicly.

    Schoinning Cats are held with high regard in AU and IMO are world class. The latest G force range has reverse bows. Although this is the first series I am aware of that has reverse bows. The G force range are highly racing orientated cruisers but the C versions are a bit heavier and have more payload at the expense of speed. However they retain the reverse bow. Obviously if they didn't, one would not recognize them as a G force. These cats are heavily represented and doing very will in AU multihull events. To my eye they are a great looking and desirable cat, unlike the other 2 mentioned previously. Streamlined cabin roofs look great, but I am also aware of the pitfalls of less space and greenhouse effect. IMO nothing looks uglier than vertical windows on a cat. I hope that style grows on me as I can see the benefits.

    [​IMG]

    http://www.schionningdesigns.com.au/www/welcome.cfm
     
  7. DennisRB
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    DennisRB Senior Member

    Also, if you look at the bows of many schionning designs, with plumb or close to plumb bows you will notice the bow sections appear to be that of a normal forward rake bow that has sort of been plumbed off and "faired in". IE the top of the stem will be wide and blunt with more buoyancy up high. Maybe he has designed it like this to add large amounts of reserve buoyancy? But it ends up looking a bit like a beluga whale at the bows. In fact I think I even saw pics of a G force which showed a wide rounded stem at the top, which almost made it look like it was a plumb bow with the top cut off at an angle and faired around. Shoinning are at the top of my list of potential builds.

    Pic from "micks spirited 480" from DIY yachts forum. I hope he does not mind me showing them here.

    Looks like it will end up with forward rake.

    [​IMG]

    Nope. It instead it has a domed nose cone.

    [​IMG]

    I'm not sure if it was this builder, but another builder on the site didn't like it so he managed to fair the shear panels into a point with extensions.
     
  8. Submarine Tom

    Submarine Tom Previous Member

    DRB,

    It's been an interesting discussion, thanks for getting it going.

    I'd have to concur with you in that I can't see much practicality and certainly little advantage to the reverse bow.

    It looks cool and may play a small part in a longer, faster hull and even a minute slowing effect in heave

    but not worth the "costs" by any stretch for me.

    I like the vertical approach but would opt for a slight overhang as a compromise.

    Cheers!
     
  9. Alex.A
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    Alex.A Senior Member

    It does seem that there is a cruiser versus racer difference tho' - after a google images search, the amount of "reverse" seems a lot more on racers than on cruisers - so the effect of the fashion is limited? You get the look without too much of the effect?
    Fashion is fashion and in a downturn economy there are bills to be paid.....
    So give the client what he wants and try and balance it?
     
  10. DennisRB
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    DennisRB Senior Member

    I am sure any passionate designer would never want to spoil the purity of his designs by giving a client something that they desire but the designer sees as pointless/detrimental. However, it also seems obvious to me that if you remove all the pointless desires of a pleasure boat client you will end up with no boat at all. I think that's something that shouldn't be forgotten.
     
  11. Richard Woods
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    Richard Woods Woods Designs

    I try to tell people the pros and cons of their choices. That way they can make an informed decision rather than blindly believing PR.

    Ultimately the customer has the final say. If he doesn't like what I design/suggest no doubt he will find someone else to draw his boat.

    However some design features are based on science and engineering. Other aspects are determined by considering the boat as a whole, not just as a sailing machine, or as a "flotel". No amount of wishful thinking or hype can change that.

    Richard Woods of Woods Designs

    www.sailingcatamarans.com
     
  12. Alik
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    Alik Senior Member

    Such rounded shapes of stem create a lot of spray at bow, especially when sailing downwind then the boat is trimmed down significantly.
     
  13. catsketcher
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    catsketcher Senior Member

    The Schionning pictured in the previous post is not a Jeff Schionning but a Craig Schionning. They used to work together but had a serious falling out. Craigs boats are built on a hull pan and he uses Duflex sheets to make the sides. Not a bad method of amateur building. You can even fit the interior with the hull side off.

    The problem for Craig's design is that the Duflex is very stiff. So you can't warp it up the bows. Therefore his bows still have flare. Now if he was to let the bows be the shape they want to be this cat would have normal (IOR) bow rake. People don't want this so the bows get a massive round to make them plumb.

    On another note we have a little GBE cat in our bay. It has vertical bows. A close look shows the vertical piece has basically been glued onto the old bows - result - no increase in flotation, extra weight, more resistance to turning and extra moment for broaching in waves.

    As an old multihuller I must admit I am a bit blindsided by the ideas of fashion affecting our boats. It used to be that everyone had good reasons for high or low bouyancy floats, masthead or three quarter rigs, daggers or keels. We could argue the merits and then make a choice. Maybe it was more back when people built their own, they would really understand the concepts behind the principles.

    People did think that sloping front windows would make the boat faster to windward with reduction in form drag. Only after living on them did we find them a sauna. Then again I never have understood Schionnings curved deck edges - why round anything you stand on? I am getting grumpy.

    Too much sanding and not enough sailing

    Phil
     
  14. DennisRB
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    DennisRB Senior Member

    Phil, like I said. Sloping roofs look great, but I think the green house effect would be bad. Also the excess use of curves seem mainly to add work/expense when building just so you can fall off your boat when its finished. But to many they look good and I am sure small gains in windward ability are to be had. I like Bob Orams designs, but he has retired. Bobs boat are duflex and don't have beluga bows.

    Adding in effect a "skeg" to the bow of that GBE for no purpose other than looks is just silly. As can be seen in the Spoonberg link I provided, there is a lot of work involved to do that mod effectively. Seems you need to start at from least 20/30% back on the hull.
     

  15. Alik
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    Alik Senior Member

    Not only greenhouse, but also the headroom and space in saloon. On those cats, 1.95m headroom is only provided at one point - at the entrance. At galley, it is 1.65m! On stairways down to demihulls one has to duck to get in an out. Yep, it looks cool and smooth from outside...
     
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