What about the old designs?

Discussion in 'Boat Design' started by big-boss, Apr 23, 2008.

  1. big-boss
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    big-boss Junior Member

    Why are the old hull shapes gone in racing boats? Like the Gar Woods, Bootlegger, etc.? Is the deep v-Cigarette that much better? Thos old boats went 60 to 70 MPH with an old V-12 or whatever with lots less power than say a Chevy BB Merlin of today- lots more weight.
    Where did all the old hull design/ Theorys go?
     
  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Change is the most essential element of all existence. Without change, the dinosaurs would still be here and we'd be furry little things, clamoring around in the rocks.

    In the early 1960's formula one cars were cigar shaped, had skinny tires and no wings, but they changed to what we have now.

    In the 1930's we had many successful hull forms, most V shaped did best at higher speeds. As time marched on, the natural refinement of these early shapes have developed into what we see today, which isn't as radical a departure as comparing a 1960 formula car to the current versions. This suggests the yacht designers in the 1920's got it very close, requiring subtle refinements to the present day forms.

    To answer your question directly, we are seeing those shapes today, but refined and tweeked a touch.
     
  3. lazeyjack

    lazeyjack Guest

  4. big-boss
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    big-boss Junior Member

    I understand the change/ time thing. Water is still the same and so is prop HP. My question is: Why did say the "baby Bootlegger" go the way of the dinasaur? Lighter engine/ Horsepower would surly have helped performance. THe change from a rounded flat bottom? To the deep-V ( knowing that the off-shore modern cats are simply Don Arno cutting a deep-V Apache/ Cigarette down the middle). How did we end up with the deep Vee?
     
  5. Tad
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    Tad Boat Designer

    Modern powerboat hull design history is a fairly thick book, with many twistings and blind alleys. Lots of folks had a hand in..... As PAR said above, Baby Bootlegger was simply outclassed by further developments. The BB hull was a variable deadrise vee bottom, with approx. 3-4 degrees of deadrise at the transom. This is fast in flat water but horrible in big waves, it will pound a boat to bits. Thus Hand and Hunt/Levi after him increased deadrise all the way to the transom to handle a sea better at high speed. More powerfull engines were being developed (war effort) by auto and airplane companies. This allowed the effective use of the power-hungry (higher resistance) deep vee. Modern boats use various forms, not just a deep-vee, as we know (through research) that one size does not fit all. Many production boats utilize variable deadrise, some use low deadrise, steps, notches, flats, pads, etc.
     
  6. big-boss
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    big-boss Junior Member

    Tad, Thanks again that is good info. Do your boats have "sort of" the hull shape of the old BB?
     
  7. Tad
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    Tad Boat Designer

    Not really even close to BB, though somewhat inspired by all right. Rooster is wider (to house twin big block v8's) and runs surface drives under her tail. Pretty and quick, about 72mph tops.

    Rooster01.jpg

    Rooster02.jpg

    Rooster03.jpg
     
  8. juiceclark

    juiceclark Previous Member

    For better or for worse, in this business what survives and evolves is what sells. We've just passed through a period where smaller boats all look the same and are rather hideous. (but quite shiney) Perhaps buyers in the < $1MM range will start demanding some style for their hard-earned money in the near future.
    Tony in Sw FL
     
  9. Eric Sponberg
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    Eric Sponberg Senior Member

    In my recent work, which includes the retro-styled Cherubini Classic 20, I specifically looked at marrying the classic hull shape above the chines with the modern underwater shape of the deep-V hullform. This is because the older designs, although fast, were terribly rough riding and a little dangerous. They were wet and sometimes hard to control in turns.

    The deep-V concept that came out of the Hunt Design office for the Bertrams was indeed far superior to the classic hull shapes. All the science of planing hullforms since the 1960s has been devoted toward refining these types of bottom shapes. Stepped hulls are a continuing development of that.

    Last year, I designed a deep-V bottom for a reproduction 21' Chris Craft Cobra, which was the 1955 design with the fiberglass tailfin on the back. It had the old style flat bottom aft and concave sections forward. I am going to write a story about this on my website soon. Basically, I took my CC20 deep V hullform and stuck it on the bottom of the Cobra. This boat is now built and running, and it seems to run well. The deep V is 20 deg deadrise at the stern, and this is a very constant shape for about half of the boat's length. The bow sections forward and below the chine are convex sections for a softer ride. The forefoot (keel profile shape forward) is shallower on the reproduction than in the original.

    My client also purchased within the last year a real original 21' Cobra which happened to be the Chicago boat show boat from 1955 which was owned by the original owner. So my client now owns two Cobras, one original and one redesigned reproduction, with two different bottom designs, and hopefully we can get some real world comparisons between the two. I am attaching some photos which should be interesting. The boat called "INTOXICATION" is the Cobra original. That is also the original trailer. You can see the two bottoms, the original flat bottom and the newer reproduction deep-V.

    The modern deep-V hullform is superior in design and performance to the designs of yesteryear.

    Eric
     

    Attached Files:

  10. big-boss
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    big-boss Junior Member

    Eric, thanks for the information. Great work! What is that wood skid loking thing under the orig. boat? IS it simply the trailer or some thing to keep it all stright?
     
  11. Pericles
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    Pericles Senior Member

    Do you mean the piece of vertical ply,timber situated over the propeller under "Double Take"? It looks like a protection for the propeller whilst reversing the rig.
    Actually, where are the rudders on both craft?

    Pericles
     
  12. SC1
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    SC1 Senior Member

  13. SC1
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    SC1 Senior Member

    Here is the new 27┬┤Super Cobrajet we at the moment are building.
    500Hp 6.6L Duramax V8 Turbodiesel / Rolls-Royce waterjet ;
     

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  14. Eric Sponberg
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    Eric Sponberg Senior Member


    I made a bit of a mistake--the stern of the "original" that I posted is that of another original Cobra 21 that was at the show, "Hemi Under Glass". The black things the boat is sitting on are the bunkboards of the trailer. The rudder is right there in the center behind the prop. The same on the reproduction, "Double Take", the bottom is clean and the rudder is the first thing you see there behind the prop.

    I am adding in the stern view of "INTOXICATION". Note the anti-cavitation plate at the stern. The original owner told me he added that plate onto the hull during his first year of ownership, after he had pitched his wife out of the boat during a turn. In that incident, and I think it was during her very first ride in the boat, the rudder had suddenly ventilated and he lost control, and the Mrs. went flying over the side. They remained married up to her death a few years ago.

    Eric
     

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  15. Tad
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    Tad Boat Designer

    Rudders??......rudders?

    We don't need no stinking rudders! Rudders are sloooow dude......
     
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