Good constant deadrise, hulled boats ?

Discussion in 'Powerboats' started by cyclops2, Oct 16, 2011.

  1. cyclops2
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    cyclops2 Senior Member

    Any body have one & loves it ? Around the 16' to 28' range.

    Rich
     
  2. Willallison
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    Willallison Senior Member

    23' Formula. One of the most enduring, highly respected and often copied deep-v hulls ever produced.
     
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  3. Mr Efficiency
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    Mr Efficiency Senior Member

    So how is 'constant deadrise' defined ? If that part of the bottom in play whilst planing is the part being considered, the Formula 233 wouldn't qualify.
     
  4. Vito Tandoi
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    Vito Tandoi New Member

    Blue Heron

    20110717_0110.JPG My little dead rise.
     
  5. Willallison
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    Willallison Senior Member

    There are very few boat's that truly have constant deadrise throughout. A flat-bottomed punt would be one of the few examples that springs to mind. But most would accept that a vessel where the deadrise doesn't vary for the aft 2/3rds would be considered to be constant deadrise.
    The obvious question though is exactly which bit of the hull do you think a 233 plane's on??
     
  6. PAR
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    PAR Yacht Designer/Builder

    The placement and profile of the chine has a lot to do with making a hull a true constant deadrise boat. Naturally, this is difficult to do if you'd like slow speed handling and other then WOT preformance attributes.

    Typically, deadrise is measured at the transom, though for a constant deadrise hull form, you'd generally see about half of the length at the same deadrise angle, within a degree or two. Again, because of the chine profile and it's relationship with the boat's centerline and plan view compromises, it's difficult to have a precisely constant deadrise angle, though within a few degrees is customary.


    As to good ones and bad ones, well it depends on the SOR. The Formula 233 hull does one thing fairly well, so if this matches the SOR you're after, then use it. Most expect more from their hull forms then WOT blasts, so pick your poison wisely.
     
  7. Easy Rider
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    Easy Rider Senior Member

    PAR,
    I hope I don't feel stupid when and if I find out what "SOR" is but I see nothing in your post that explains it. WOT is so common I have no problem w that but SOR ??
     
  8. Willallison
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    Willallison Senior Member

    Easy - SOR = Statement of requirements

    Par - yep, the 233 is only really happy at speeds above 25 knots, I agree.
     
  9. PAR
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    PAR Yacht Designer/Builder

    Statement Of Requirements and a standard set of values placed on the design as a concept, to determine ultimate goals, scantlings, preformance envelop(s), use expectations, suitability for expected sea state conditions, etc., etc., etc.

    This, sometimes quite convoluted and complex set of requirements, is established early in the design process, which helps to a very large degree to set the shapes, equipment, propulsion, etc. installed or incorporated into the design.

    In the above, lets assume the owner wants a relatively comfortable powerboat with accommodations to suit 4, mostly used in lakes, rivers and small bays, with an occasional outing near shore in mild sea states. Selecting a deep V variant of a down sized, offshore racer, doesn't suit the SOR very well. It will blast along quite nicely and handle the occasional off shore blasts but, come inland and you've got a pig, that's uncomfortable, unwieldy at the helm, even at modest speeds and don't even think about trips very long in no wake areas, as your arms will fall off from all the "helm chasing" they'll be doing.

    This is the whole point behind an SOR. The first thing I do is ask a client for lists of the perfect world yacht and then another of the absolute bare minimum they could live with. Each item is examined, accesses and prioritized and a new, more realistic list generated. This focuses the search if looking for a design or guides the designer if a new design. Only with this level of subject understanding, can you expect the goals of the project to be met. Anything less then this usually results in a lovely boat that has elements that you wish you'd payed more attention to during the design development or selection stage.
     
  10. Willallison
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    Willallison Senior Member

    I wonder where our Op has gone....? I posted the Formula as an example because we do have one of its derivatives... a boat originally built by an abalone poacher! Tough as nails... unstoppable in a slop and a surprisingly good dayboat. Indeed my wife & I spent almost a week aboard it back in the long lost days before we had children....
    Being able to lope along at 40 knots adds a whole new meaning to the idea of "cruising".....:D
    Would it by my choice for an inshore cruiser for a family of 4? No... that's why I designed Graphite (which is also a monohedron for the aft 3rd of its length). But there was no mention of an SOR, hence my putting it forth....
     
  11. cyclops2
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    cyclops2 Senior Member

    He returns.

    Helping a bussiness friend stay afloat. Being retired during a Depression is impossible. To many people need my mind.

    My biggest complaints are the Chaparral wanders left & right off plane. It also can not transition from off plane with 4 aboard to a plane speed of 25 mph. The climb out notch start at 10 to 12 mph. Most old woodies I try to cruise with run in my climb out notch range. 15 to 25 mph.

    So I run off to the side. Or most often I ask for a boat ride. My biggest complaint is that huge climb out notch range between 12 to 25 mph. Want to know the notch ANGLES ? Very near 35 degrees. It LOOKS stupid while the woodies are sliding along in unison.

    The Chaparral is a fantastic boat in unexpected & dangerous water :) & when run at the speeds it needs, to be a joy.
     
  12. PAR
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    PAR Yacht Designer/Builder

    Cyclops, your expecting too much from this boat. They all do this and it's indicative of the breeding. If you want to climb up quickly and fairly level then you have to kiss off all that deadrise.
     
  13. cyclops2
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    cyclops2 Senior Member

    Finally. I am starting to realizethat the warped bottom boats are SUPREME below 30 mp

    I did a lot of reading on these 2 basic hull designs in past postings on these hulls. some go back to 2004.

    Warped slow & efficient. But CAN be viscious if overpowered. Bow hooking / pivioting at high planing speeds.


    Modified deep V. Use it if you are a + 40 mph speed lover. ....That is what I came away with.

    So the Chaparral is my go to boat, when I want to flip the keys to anyone to go out WITHOUT me in the boat.
     

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  14. cyclops2
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    cyclops2 Senior Member

    1 of these boats is in a nearby museum for me to get the bottom right.

    A old design discussion group here said to NOT use a very FLAT bottom. V the flat to 7 degrees to stop the viscious hooking & rear end oscillations.

    Sounds right from what we know now ????

    My Son in Law & I have the common desire for a woodie of this size.
     

  15. michael pierzga
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    michael pierzga Senior Member

    A normal motorboat for medium power, medium displacement , good behavior at reasonable speed, goes kinda like this...

    the sharp ended bow works thru waves, deflects spray and gives you sea keeping ability

    the forward middle of the boat supports the engine mass, crew, tanks and carries a sharp vee profile , plus internal strengthening , to SMASH thru a wave

    the stern flattens out to form a planning shoe.


    Deep Vee craft are special purpose and represent a huge compromise in comfort and efficiency for everyday use.
     

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