Trimaran Objectif Rhum 39

Discussion in 'Boat Design' started by philippe p, Apr 11, 2020.

  1. philippe p
    Joined: Apr 2020
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    Location: france

    philippe p Junior Member

    Projet de trimaran de croisière hauturier de 39 pieds

     

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    Last edited: Apr 11, 2020
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  2. Ilan Voyager
    Joined: May 2004
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    Location: Cancun Mexico

    Ilan Voyager Senior Member

    Hi, welcome to the forum.
    May we have more details about the tri. Building material, dimensions, displacement etc...
     
  3. philippe p
    Joined: Apr 2020
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    philippe p Junior Member

    This harmonious design by Philippe RIVIERE (Philippe RIVIERE / Yacht Designer | ARCHITECTE NAVAL http://www.philipperiviere.com/wp/) of classic design (without giving way to reverse bows), offers two double berths - including the one at the rear located at the waterline which should turn out to be very pleasant at sea -, a shower room wc, a chart table corner, a small "L" seat (which can be used as extra sleeping) with its table for meals and a long kitchen facing it. All the fittings benefit from a beautiful height under the beam and a sufficient height above the berths to be able to sit.
    Storage should not be outdone given the volumes still available.

    Outside, this trimaran is distinguished by its large cockpit which extends along the rear arm with two deported and protected helm stations. Two watch stations are located in front of the descent, which are sheltered by a large hood.
    Particular care has been taken to facilitate access and safety on the deck by gangways placed on each side of the deckhouse which turns out to be very slightly domed and slightly raised.

    On the power side, the trimaran has an upwind surface of around 85 m² for a mast of 15.40 meters. The mast height and the sail area are reasonable, but they could be increased according to the wishes of the future owner. .

    This sorting is provided with bulky floats. The design, with slightly V-shaped bottoms, should encourage a more comfortable passage in the rough sea and above all should be more tolerant in the event of overselling.
    The foils remain optional ...

    This trimaran can be built in foam or strip planking

    LENGTH: 11.90 M.
    WIDTH: 10 M.
    WEIGHT: 3000 KG
    TRAVEL: 4000 KG
    WING MAT: 15.40 M.
    SAILS AREA: 83 M2

    MOTORIZATION: inboard 30 cv

    Could be suitable for a Route du rhum.
     

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  4. Niclas Vestman
    Joined: Aug 2017
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    Location: Malmoe, Sweden

    Niclas Vestman Senior Member

    Salut Philippe! Interesting design. I'm a total amateur, but would share a couple of thoughts if you don't mind.
    1) The cockpit looks like a serious performance sailors dream! Large, safe, comfortable and weight redistribution friendly.
    2) No sleeping or chart-/comstation near the cockpit or helms, for routing/resting or toilet needs while shorthanded sailing. Also makes communication and navigator/radio operator more difficult. For racing, maybe one alternative might be raising the sole under the navigation area, making it accessible with fewer steps and placing an "emergency" toilet (portapotti) and a low headroom helmsmans resting bunk (preferably with small windows giving views of forward sea, and general sailtrim/position) opposite the raised navstation.
    3) The central hull shape seams a little unorthodox. Difficult to judge just by eye. But, a) it looks wider at the waterline, than a true racing/performance crusing tri. Length/width looks closer to 1:12 ratio. For racing my guess would be that most would strive for 1:16 or better.
    b) the vertical curvature lengthwise is both quite pronounced and unusual. The aft most 25% end in a concave finish towards the stern. And also almost goes up to the DWL.
    To me it seems that modern performace tris have a much straighter bottom profile lengthwise. In part not to suck the hull downwards at speeds above 1,5x hullspeed. And also because at those speeds, the flow seperates cleanly from the square stern anyway, creating way less drag then being sucked along a curvature terminator near DWL.
    But as I said, I am just a total amateur. Maybe taking a peak at the totally new Dragonfly 40 and the newish Grainger designs for a comparison, could be a good idea?! But still, cool design. Thanks for sharing!
     
  5. philippe p
    Joined: Apr 2020
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    Location: france

    philippe p Junior Member

    Bonjour Nicolas,
    My English is not very good, I hope I will be understandable.
    - The Objectif Rhum 39 project which was presented can still be modified, it is not final, even if it is very advanced.
    - It is a cruising racing trimaran, so it is not the best performing racing boat in this category and it is not the most comfortable 40 foot triman. It is a compromise between cruising and racing (solo) that has been thought out, without concession with the effects of fashions, but by adopting thoughtful choices which can - to a certain extent - be modified in consultation with the architect. .
    - For a U shape a good ratio is effectively a width / length of 1/12. But Philippe RIVIERE - and other architects - get very good performance with larger and more flat hulls. The shapes of the back of the hull have already been modified with more volume, the concave shape has been removed (see the new picture).
    - Other modification: The mast was also slightly moved back (new picture).
    - We estimated that the watch station (or watch seat) should be located near the descent, with the navigation instruments under the cap. it's enough. It is planned to be able to steer from this standby station (which the photos do not yet show). If you want to lie down, the best place will be on the indoor bench near the chart table.
    The cockpit is indeed very wide, deep and secure, a bit like on racing boats. it will no doubt be possible to add an articulated bench seat along the rear beam. This cockpit should also provide a pleasant space for mooring if it is protected with a large tarpaulin.
     

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  6. Niclas Vestman
    Joined: Aug 2017
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    Location: Malmoe, Sweden

    Niclas Vestman Senior Member

    Interesting I did read that the famous Ian Farrier had mentioned that his F9AX, the extra wide waterline version, might be slightly faster than the regular F9A. Another designer that has designed a wider waterline, is Tim Clissold. Allthough it might not be comparable since that design is a smaller, TC666/660 and TC627. They might behave more like dingies. I don't have the expertese to really comment.
     
  7. philippe p
    Joined: Apr 2020
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    Location: france

    philippe p Junior Member

    Some modifications.
    The mast has been moved back, the daggerboard is located in front of the mast.
    With a mast retracted, the presence of the bowsprit is less useful or necessary.
    the dinghy finds its place at the rear of the cockpit beam.
    It should also be noted that the buoyancy volume has been increased on the rear of the central hull
     

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  8. philippe p
    Joined: Apr 2020
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    Location: france

    philippe p Junior Member

    the stability curve and some photos of the trimaran at 17.8 °
     

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  9. Heimfried
    Joined: Apr 2015
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    Heimfried Senior Member

    The ordinate of the stability curve shows no unit, only numbers. Is the dot inside those numbers the decimal point or the separator of thousends?
     
  10. philippe p
    Joined: Apr 2020
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    Location: france

    philippe p Junior Member

    the curve shows the maximum straightening moment which is reached by a heeling of 18.7 ° with a force of 17,385 kg.
     

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  11. Heimfried
    Joined: Apr 2015
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    Heimfried Senior Member

    A (righting) moment can not correctly be expressed as a force. Kilogram is the unit of mass, multiplied with gravitational acceleration (g in m/s^2) it becomes a force (expressed in Newton). Further multiplied with a appropriate distance it becomes a moment (N * m).

    The ordinate of stability curves is usually given in meters which is derived by dividing the righting moment by the displacement of the vessel (mass) times g.
     

  12. philippe p
    Joined: Apr 2020
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    Location: france

    philippe p Junior Member

    Différentes configurations pour le mât aile

    [​IMG]
    [​IMG]
     

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