Reverse bows on cruising cats pros and cons

Discussion in 'Multihulls' started by DennisRB, Mar 1, 2013.

  1. DennisRB
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    DennisRB Senior Member

    Yeah. I agree. I mentioned the headroom point earlier.

    Does anyone have some pics of designs with more practical coach roofs that still look nice?
     
  2. Corley
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    Corley epoxy coated

  3. DennisRB
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    DennisRB Senior Member

    I already have that site bookmarked. Great boats. Just don't like the idea of building and fairing all those curves! I would love a 13.5

    :eek::eek::eek::eek::eek::eek:

    [​IMG]

    Are you sure there is not too much wasted space in here? Cabin top looks tiny.

    [​IMG]

    [​IMG]
     
  4. Corley
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    Corley epoxy coated

    The cabin top looks tiny but it's not small in there because the edge of the hull sheer adjacent to the bridgedeck is higher as well. On the Schionnings or on the Oceanic kit catamaran for example there is acres of space under the angled windows but you cant really do much with it. The Whitehaven seems to have more useable space. If I was in your shoes I'd get myself onto as many cats as possible to see in person what you think about the arrangements. It's often not a case of not much more space more how you feel about the space and how it's configured.

    From a practical perspective there is a lot to recommend the Chris White style pilothouse/front cockpit arrangement. The front cockpit makes a nice place to steer from with great access to all your winches and lines at the base of the mast and the inside pilothouse helm is excellent too and offers protection from the elements. I would not say the arrangement is very aesthetic though.
     
  5. Ilan Voyager
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    Ilan Voyager Senior Member

    Knowing these two guys I'm sure there is no problem. VPLP has a very long experience of very successful designs. They have a a technical database that makes the other multihull designers except Irens and Cabanel simple amateurs, with enough matter for at least 5 PHD in naval architecture, engineering and hydrodynamics. You can imagine that all that is locked for their exclusive use.
    In 20 years they have designed more multis than all the australian and american NA together in the same lapse of time...and they use the services of the best aero-hydrodynamicians and engineers in the field.
    Do not worry, just a design trick for the customers able to spend 10 to 20 million bucks in a yacht, and leave 10% in architect fees (yes they are very expensive...).
     
  6. Alik
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    Alik Senior Member

    In sailing catamarans, maybe yes... But maybe just because sailing cats is a very limited niche and most of designers do not want to sit there only. Besides, M&M from US has comparable experience and record.

    In power catamarans - no.
     
  7. brian eiland
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    brian eiland Senior Member

    Just starting to read thru this subject thread, but had to site these two observations before I forgot to by the end of the thread....shorter memory with age ;)

    I agree with you Richard





    And you got it right as well Phil. Those new bow shapes are 'fads' on cruising boats.

    To tell the truth I never embraced the plumb bows on production cats when they started to appear. To me they made the boxy multihull shape even more boxy.

    Here is a pretty and functional shape hull and bow for a cruising cat.
    Investigator Skeg.jpg Investigator bottom.jpg

    ...or if you were dead set on a plumb bow, here is a superior looking one from Lock Crowther...his Wahoo
    http://www.boatdesign.net/gallery/showphoto.php/photo/5406/ppuser/399
     

    Attached Files:

  8. brian eiland
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    brian eiland Senior Member

    Great posting Petros. Now those bows had an alternative purpose to sailing performance. :D

    Edited:
    At first I mentioned this in a joking manner, but I thought I detected someone thinking there was a 'sailing function' to these bow designs. No, they were not. These bows were designed to be battering rams, puncturing devices against the Islamic fleet of naval vesesls invading Greece
     
  9. brian eiland
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    brian eiland Senior Member

    This reminds me of those many French production cats that were built of hulls in two halves and then required a large blunt bow in order to glass the interior of the joint.

    Downwind they pushed up large amounts of water to be sprayed back over the vessel.

    I've always thought that this type of a construction with a flat-sided collision bulkhead up front, onto which could be glued a sacrifical bow shape made sense. This might permit 'your choice' of bow shapes (fashioned from hi-density foam/glass) for particularl occassions :idea::D (your dress for the party)
     
  10. Submarine Tom

    Submarine Tom Previous Member

    Not sure how to break this to you Brian, but that's not a plumb bow in your post #82...

    It is, however, the amount of over hang I prefer.

    Isn't plumb vertical?
     
  11. Petros
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    Petros Senior Member

    this style of bow far pre-dates Islam by many centuries. They appears even of merchant vessels and were not particularly heavy as a battering ram might be. So there has been many guessing on why this kind of bow was used, but on the Severin trip it was determined that this reverse bow design put the bow wake far enough away from the hull that the first several ranks of rowers could keep in time with the others without having their long oars cut through the bow wake. So it had a very practical performance reason to have it on hulls that were mostly driven by ranks of oarsmen. they also used it for boarding and disembarking from the boat, the bow could be beached without risk of grounding the vessel.
     
  12. Moggy
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    Moggy Senior Member

    With respect Brian in my experience a traditional flared bow generally throws more spray further out which is then blown back over the boat. This is one feature that makes my little boat very wet indeed. It also dramatically increases drag as the boat buries her bows which very much works against you.

    The design feature I would like to change most about my boat is the bows, IMO they need to be a flatter side with a plumb bow so that the spray is not thrown so far, the increase in buoyancy is more lineal and the drag is lower. Chop slows my boat dramatically and soaks you in the process IMO it is all due to the shape of the bow area.

    ... but then I am just a lay sailor, not a designer.

    Richard,

    I this does not gibe at all with my experience of a traditionally flared bow on a cat. Most every finer bowed straighter stemmed boat that I come across always looks so much drier that my boat!

     
  13. Submarine Tom

    Submarine Tom Previous Member

    I love vertical stems but they are notorious for collecting flotsam in these parts.
     
  14. oceancruiser

    oceancruiser Previous Member

    Perhaps you have overlooked the extra bouyancy under the bridge deck, which is perhaps the reserve bouyancy factor and breaks the bow wake from the depressed lee hull from slamming the windward hull. From what I can see what you are saying the water on the top bow surface in all probability would not happen as the boat would shudder and stall but for the center extra bouyancy under the bridge deck. If the water did get there - well - Look how low the cross beam is - the low bow spit is - the low tramps are - all would be under water. The shuddering would be tremendous and the helmsman / crew would taken evasive action long before a pitchpole event would take place unless one would be sailing on auto pilot and every one is in their respective cabins with there favourites. The designer is the foremost designer in the world re Multihulls so obviously the extra bouancy under the bridge deck supposedly prevents this. The bows to me look like they are sloping outward not inward.

    The almost flat bow decks overcomes the complaints other owners are critising [Craigs and Jeffs ] designs as not having enough room to be able to walk safely on the bows going forward.
     

  15. Moggy
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    Moggy Senior Member

    If the boat is designed and laid out sensibly why would you need to go forward of the front beam? Surely bow deck area need not be an issue at all on a cat?
     
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