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RADICAL New Hull Design...

Discussion in 'Technical Discussion' started by SAB, Mar 13, 2005.

  1. SAB

    SAB New Member

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    A 70metre concept produced for an Aussie client. The design proposes a float-in-tender dock which can be used as a swimming pool, with bomb doors / a central atrium thru 4 decks / expansive use of glass / curvaceous styling which is integral to the structural elements as well as being aesthetic.

    This design pushes the envelope in regard to concept and styling for new Superyacht proposals, and doesnt try to adhere to any rules so the creative objective could be realised.

    SABDES - www.sabdes.com

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  2. catmando

    catmando Senior Member

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    Who's building it? Will it have the 'wave piercer' design?
  3. SAB

    SAB New Member

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    SABDES 70

    The hullform for the SABDES 70 is a planing monohull form, though along the way we did develop an original idea for a hull which morphs a monohull with cat-pods aft as seen in attache piccy; the purpose so the float-in-dock would be open all the time without need to flood. The wavepiercer hullform didnt suit the concept ideas correctly, though there is a trimaran hull seen on the NWBS yachts 61m E-motion was considered ok.

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  4. SAB

    SAB New Member

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    SABDES 70

    ... we had quite a bit of interest from UAE customers, but as yet the vessel hasnt been built. International Shipyards Ancona have also been interested.
  5. catmando

    catmando Senior Member

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    You're saying that 220' hull will plane off??? WOW!! :eek: :eek:

    I saw the E-Motion in Boats USA magazine(Dec. issue). That hullform design will provide lift and stability, thus reducing power needed for operation, and increasing fuel efficiency.

    I like the design of your vessel, very modern and forward-looking. I like the "cat-pods" idea too. Innovation is key to sales, especially when it's out there for all to see.

    Two thumbs-up from the catman! ;) :)
  6. SAB

    SAB New Member

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    ... anything will plane if it goes fast enough... maybe, as the song goes... 'with a little bit of help from my gasturbines'.
  7. JonS

    JonS Senior Member

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    That hull seems pretty radical.

    I designed a boat last year with two engine pods kinda 117 Blackbird style. If i can find an image on my back-up cd, i'll upload it.

    I certainly think it would be really neat to see something like this for real. Interesting to see how it would look, and work, with stress and strain points, etc.
  8. AMG

    AMG YF Moderator

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    Hmmm,
    The B&V yacht Eco/Enigma of the same size is having twin diesels of 5.000 hp and a gasturbine of 18.500 hp. They still needed a foil added under the stern to get her "planing", so it isn´t that easy...
  9. SAB

    SAB New Member

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    Here are a few more renderings of that particular hull, and the original BIC pen concept development sketch. Should be somewhat self explanatory looking at the images; The design idea we termed the 'aqua hull' evolved for the need to have a 'float-in-dock' that allows guest tenders to enter, but without the need to keep flooding and draining the dry dock... also the trim and stability remains the same if it always is open to the water. The morph takes place at the chine underwater, so the hull looks completely like a nomal monohull except from aft. The keel of each pod is off centre (outboard) making the deepest part of the pod as far outboard as possible to also increase stability. Vee sections at the morph point, and a tapering flat run as it goes aft, allow the pods to still provide lift. A trim-tab could be configured to deflect spray away from the dock bay. Tenders could be stored port and starboard and lowered to the centreline of the vessel, this further reducing change of trim, as seen on most Superyachts today where the boats are sent outboard. Hope that explains it more clearly... we dont have all the answers yet, as it was just an idea and we reverted to a more conventional hull for the SABDES 70.. However, when I was a kid I saw a 15' plywood model (in 1982) of a wavepiercer cat in Hobart, with an extended shaft on its Johnson motor so it could reach the water... that was the start of Incat wavepiercers. SABDES

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  10. Remy

    Remy New Member

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    It appears to me to be kind of a revolution in hull design. The shape is quite unusual, and not only for the stern.

    I bet it's gonna work very well...
  11. D'ARTOIS

    D'ARTOIS New Member

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    To push a 63 mtr yacht with a displacement of 500 tons (very very light weight construction) you need approx 40.000 hp to push her up to a little above 40 knots;
    Frank Mulder proved with "Moonraker" that those speeds are not unreal to achieve, however if the yacht gets larger, other and bigger problems are popping up.
    Next to that, what is the advantage of a yacht at planing speed: even a destroyer, capable of doing 40 knot+ doesn't plane..... I am a little sceptical but I am involved in the making of fast moving surface vessels.
    BTW - the later owners of Moonraker took out the gasturbo..... the high speeds were intolerable........for crew and passengers.....
  12. AMG

    AMG YF Moderator

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    This happened to the Mulder design Lambda Mar as well... ;)
  13. YachtForums

    YachtForums Publisher/Admin

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    SABDES,

    Sorry for the delay, I was out of town yesterday...

    A number of years ago, I worked with a research team that utilized the facilities of the David Taylor Research Center; the Carderock Labs in Bethesda, Maryland and the Large Cavitation Channel in Memphis, Tennessee. These facilities are funded by the Department of the Navy, as was our research group.

    We used the High Speed Basin in Bethesda to analyze hull and foil development, while the Memphis facility was used for propulsor and appendage studies. Most of my work was conducted in the fields of water-jet propulsion and high speed hull designs.

    I've got a little more knowledge than the average park bear in this area and after studying your monohull-sponson concept, it may be one of the most revolutionary hull designs I've seen in years.

    There appears to be many benefits, beyond tender deployment...

    1. An exceptionally low drag coefficent.
    2. Inherent stability.
    3. Displacement efficiency with planing cabability.

    I'm confident that this configuration could achieve plane, and may not require the horsepower that others have speculated on. There are a couple of ideas that come to mind that may aid in achieving plane...

    1. A stepped surface to break adhesion or a re-vamp of the main hull aft section.
    3. A keel level pad. This would have no real adverse effect on displacement efficiency, but would help develop lift for planing speeds.

    Any of these combinations would result in a 3-point lifting surface. There is one reservation that comes to mind... there may be some bow-wave interactions associated with the sponsons that will not be favorable. Tank testing could isolate any occurences and modifications of the sponsons could help reduce this interaction.

    Setting aside planing speeds, which is not a high priority for yachts, the real advantage to this hull shape appears to be for displacement speeds. I for one... applaud your design. :)
  14. SAB

    SAB New Member

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    Thanks for the positive review... its great to hear your comments are reinforcing the whole ideas behind the hull shape which would also provide good at-anchor stability due the triangulated footprint, ie:main hull and 2 sponsons. The achievable speeds of the hull form would need full tank testing, which hasnt been done as yet, before deciding what its operational best would be. A semi-displacement speed range (18-25knots for 50m/165' hull) may be its best category, with improved fuel efficiency achievements; it would make a strong alternative to a traditional mono-hull, with some of the advantages (but none of the, debatable!, aesthetic issues) of using a tri of cat hull, for a Superyacht. To achieve high speed 30+knots, it may also work with a T-foil fwd, or hydro foil fwd, to provide some extra lift, and a flat plane between the sponsons aft... I agree the interaction of the sponsons would need looking at the results. As they are shown they are made wider than the monohull to increase stability, and could be made less. The approx ratio lengthwise of monohull is 75%, to the cat sponsons about 25%, thus keeping good inherent stability. The design lends itself well to waterjet propulsion. The 70metre SABDES design, we realistically proposed twin 6000hp diesel engines driving CPP to provide speeds in the range of 25+ knots... and a booster gas turbine for anything 35+ range for the non-wimps out there!
    ... shake rattle and roll... SABDES
  15. YachtForums

    YachtForums Publisher/Admin

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    Initially, this was my first thought as well. But...

    Shafted propulsion in the monohull section would not be favorable due to trim and CG considerations. However, waterjet propulsion in the sponsons may have their own challenges as well...

    If the sponsons are running in a turbulated flow, induced by the bow wave, the intake gullets of the pumps may be prone to ventilation. This may be further compounded by the recessed (raised) position of the sponsons.

    Typically, jet pumps are most efficient when placed at keel level, or the deepest section of the hull. They are prone to loosing vacuum when placed outboard, generally because this is a more aerated section AND because any lateral hull oscillation can break intake vacuum on one side, or the other. With a tri-hull configuration, this will most likely result in constant course variations while operating in rougher water. (On a more positive note, this might be the first hull ever developed that would allow jet pumps to work effectively in reverse, as there is no hull interference for backwash.)

    I'm leaning toward traditional shaft propulsion in the sponsons for several reasons...

    1. The depth of the shaft (and ultimately props) will offset the raised position of the sponsons, placing the props deeper than a jet pump. Aeration considerations would be minimized, as would course variation.

    2. The angle at which the shaft exits the sponsons, which ultimately induces negative trim into the bow, is compensated by the extended length of the sponsons. In other words... the longer the boat, the less trim is induced by shafted propulsion.

    3. As a planing hull, surface drives might be an option. Typically, surface drives sacrifice low-speed maneuverability, but the width of drive placement with outboard sponsons, coupled with no reverse-backwash resistance, might prove to be a favorable platform for these drives.

    These are just some random thoughts. It's not my intent to "critique" your work. It's the first new hull design to capture my imagination in years and I enjoy exploring the possibilities. :)
  16. SAB

    SAB New Member

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    shaken not stirred

    On the question of propulsion for this type of hull, and since the concept behind the SABDES 70 (which we termed 'Sleek Princess'), is an attempt to create excitement for the guests 'yachting' experience, and also technical innovations like the hull design, then the propulsion might suit using a 360degree pod propulsion system like ABB have in their Compact Azipod product (see image). The hull form seems to lend itself to semi-displacement, as does the podded propulsion system. For higher speeds, 25+knots, the surface drive system would be a good option, noting your comments that waterjet propulsion would likely have intake aeration problems. The other advantage of using a podded electric propulsion system, is in allowing flexibilty for the location of the main generators, and increased manouverability, and having the props of the pods deep enough so as to avoid any aeration problems. To complement the innovations of the hull and propulsion system, why not also look at Fuel Cell System (like Ballard) to provide the energy. .. All possible and current technologies.. like James Bond! ... - SABDES

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  17. Donald Blount

    Donald Blount New Member

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    Having designed vessels from 42 to 67 meters O A which have been built and sea trialed at speeds substantially above 50 knots, I question the buttock shapes of the monohull portion of the hull as being somewhat non-lifting in the hump and higher speed ranges. The monohull bottom shape is analogous to attempting to making a canoe plane. Negative dynamic hull bottom pressures will be developed beginning near 25 knots which may "pull down" the bow instead of lifting it.

    My advice is to carefully study this hull form with realistic model tests before marketing energy takes control of decisions on committing large financial resources.
  18. SAB

    SAB New Member

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    Thanks Donald for your review and sound advice. I agree with all your points, particularly that the main hull buttock shapes need refining.

    In the interest of achieving a monohedron hull form, one proposal could be as per the new image I attach; At speeds <20kn the mainhull acts as a displacement hull, but as speeds increase >20kn + the addition of chine flats and running strakes aid lift. At the point where the main hull buttocks begin to curve upward, the chine flats and strakes stop and a step in the hull is added. The aft part of the main hull would lose resistance due to being recessed, and the hullform then becomes a 3 point planing surface, ie: main hull and aft sponsons. Weight distribution woud be critical for the correct trim angle, and the effects of the rooster tail would need careful consideration.

    The SABDES 70 hullform in our later versions reverted back to a standard monohedron form, as can be seen in the attached early concept study image from 3/4 aft. Note the transom seen underwater.

    Marketing wise, the idea for the hull form was not so much to reinvent the wheel while achieving high speeds, but an attempt to find a solution to create a hull form allowing the 'float-in-dock' without the need for constant flooding and draining. (as seen for eg on Princess Mariana, and some Naval Vessels). I came from a Naval design background, which was my inspiration in developing ideas for a 'float-in-dock' for tender deployment on Superyachts.

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  19. SAB

    SAB New Member

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    AMELS - The STASH concept

    Amels have been producing a design where they split the Monohull aft into a Catamaran. They call it 'the STASH concept' (Single to Twin Aft Ship Hull).
    Their basic idea is again to create an inside harbour for large tenders. Benefits are the tenders are located at the centreline, and the dock does not have the need to flood. The STASH was developed over a period of one year by the Amels Design Department with special contribution by Dirk Degroote, and was presented at 'Project 2004' Amsterdam Nov 2004.

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  20. YachtForums

    YachtForums Publisher/Admin

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