Monocat Hull

Discussion in 'Boat Design' started by trimix, Apr 29, 2005.

  1. trimix
    Joined: Sep 2004
    Posts: 40
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Vietnam

    trimix Junior Member

    Did someone here experienced this hull type ?
    Pro and cons ?

    Attached Files:

  2. trimix
    Joined: Sep 2004
    Posts: 40
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Vietnam

    trimix Junior Member

    I've forgotten to precise that it is a motor boat
  3. im412
    Joined: Jan 2005
    Posts: 61
    Likes: 1, Points: 0, Legacy Rep: 5
    Location: australia

    im412 Junior Member

    i can't really help ..but the yamaha ub580 panga has a similar center line to the hull
    and then going to a 15-20deg or so deadrise \_/ [i dont know the right term]
    yours has starts at half the hull length the ub580 starts about 1/3
    the i think is a similar hull

    so on a narrow scale that shape workes extreamly well...i think
    i dont know how it would go having the whole hull like it
    might pound a bit ..dont know..air mix under the hull would be important

  4. intrepid71
    Joined: Jan 2005
    Posts: 92
    Likes: 4, Points: 0, Legacy Rep: 39
    Location: Connecticut

    intrepid71 Junior Member

    I don't have experience with the hull type, but I have doubts about the shape you have shown. If this boat is supposed to travel at planing speeds I would think you would want a sharp transition between the forward monohull section and the aft catamaran section. The sharp transition would act as a step and facilitate flow seperation, which would allow an air cavity to form between the aft cat hulls. This would reduce wetted surface and hopefully the overall drag. As it is shown now, with the faired transition between shapes you will not get any flow seperation and the bottom will be fully wetted from bow to stern. The bottom will act as if it has a large hollow in it, which I suspect will have higher drag and worse handling characteristics than a simple straightforward monohull shape.
  5. marshmat
    Joined: Apr 2005
    Posts: 4,127
    Likes: 149, Points: 63, Legacy Rep: 2043
    Location: Ontario

    marshmat Senior Member

    I've never actually seen a hull like that before...
    If that thing's supposed to plane, as the forefoot shape would imply, it would be rather inefficient as Intrepid said. It could be a semidisplacement hull- still an odd shape for that, though, as that big hollow in the aft section of the keel would seem to suck the stern down at speed- the exact opposite of what a planing or semi hull needs.
    I'd like to see that thing from other angles- it might be shaped with a sharp forefoot and a smooth, level transition to the cat section, which would probably be pretty good for pounding through bad waves. It would be nice to see more of the boat, maybe some weight/length/power numbers.
  6. trimix
    Joined: Sep 2004
    Posts: 40
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Vietnam

    trimix Junior Member

  7. squinsin
    Joined: Mar 2006
    Posts: 1
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: australia

    squinsin New Member

  8. KCook
    Joined: Jan 2003
    Posts: 171
    Likes: 2, Points: 0, Legacy Rep: 13
    Location: Arizona

    KCook Senior Member

    Does sort of look like a displacement design trying hard to relieve the stern wave?

    Kelly Cook
  9. bhnautika
    Joined: Feb 2006
    Posts: 852
    Likes: 57, Points: 38, Legacy Rep: 571
    Location: australia

    bhnautika Senior Member

    This is not a new hull form. The largest boat of this type was Cousteau’s “Alcyone”. This type of design tends to have a short roll period, which can be uncomfortable in some conditions.
  10. gerard baladi
    Joined: Nov 2004
    Posts: 58
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Egypt

    gerard baladi Junior Member

    It reminds me of the "Stolkraft" design, and how little this concept is talked about.
  11. phryd
    Joined: Mar 2007
    Posts: 2
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: aix en provence

    phryd New Member

    Hi, I am the architect of the monocat shown on this site.
    If you need further information, you can contact me.
    Best regards
    Philippe RENAUDEAU - PhR Yacht Design
    Architecture et construction navale
    Mobile : 06 86 82 99 53 - Tel : 04 42 51 29 92
    Le gîte des vents - 7, rue de Valcros - 13090 Aix en Provence
    SIRET : 482 487 303 00018 - Code APE : 743B
  12. kach22i
    Joined: Feb 2005
    Posts: 2,418
    Likes: 111, Points: 63, Legacy Rep: 1222
    Location: Michigan

    kach22i Architect

  13. Willallison
    Joined: Oct 2001
    Posts: 3,590
    Likes: 130, Points: 0, Legacy Rep: 2369
    Location: Australia

    Willallison Senior Member

    Philippe - perhaps you could explain the thinking behind the monocat to us a little more...?
  14. phryd
    Joined: Mar 2007
    Posts: 2
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: aix en provence

    phryd New Member

    Thank you both for answering. This hull concept is anything but new. The main interest is to mix advantages (and a few disadvantages I must admit) of mono and multihull. My english is unfortunatly not technically speaking good enough for a full explaination, but this design offers a wide and open space for day life, and due to the wide beam, the displacement is rather light to allow good performances. You can have a look the the last version of this concept on may web site (B-one concept 50), and a 2 pages press article will come out next month in "Loisirs Nautiques" in France.

  15. tri - star
    Joined: Feb 2007
    Posts: 87
    Likes: 1, Points: 0, Legacy Rep: 3
    Location: Vancouver, B.C., Canada

    tri - star Junior Member

    To geradi baladi:

    The hull form does have some similarities to the Stolkraft form.
    There are also some important differences.
    The most significant, being, that one is less speed limited than the other.

    Most recent licenced people - who are involved with the Stolkraft
    francise - that I know of, are the NA firm of AAA. In Seatle, Wash, USA.

    Cheers !
    Last edited: Mar 18, 2007
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.