Multihull Capsize Prevention <split>

Discussion in 'Multihulls' started by MikeJohns, Jun 23, 2011.

  1. warwick
    Joined: Jan 2012
    Posts: 423
    Likes: 7, Points: 18, Legacy Rep: 63
    Location: papakura south auckland new zealand

    warwick Senior Member

    Good point about using a bolt (hurricane) hole Cavalier mk2. I suppose it would be fair to say that at that stage you will be to busy Making sure you have your anchor points right eg: mangroves tree bases or what ever to worry about much else.

    there has been a couple of articles in the Multihull world magazine, and one about surviving location flooding.
     
  2. Corley
    Joined: Oct 2009
    Posts: 3,744
    Likes: 175, Points: 63, Legacy Rep: 826
    Location: Melbourne, Australia

    Corley epoxy coated

  3. MikeJohns
    Joined: Aug 2004
    Posts: 3,176
    Likes: 198, Points: 63, Legacy Rep: 2054
    Location: Australia

    MikeJohns Senior Member

  4. Angélique
    Joined: Feb 2009
    Posts: 3,005
    Likes: 318, Points: 83, Legacy Rep: 1632
    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    That's where a center cockpit in front of the cabin may come in handy . . . . as well as some window and cabin reinforcement for this scenario behind a stern sea anchor . . . :D - - (a drogue may be wiser though)

    _Chris_White_Atlantic_Cat_42_Stern_.jpg - _Chris_White_Atlantic_Cat_42_Center_Cockpit_.jpg
    - click pics to enlarge

    Pics are from a Chris White Atlantic Cat 42 sales ad.


    By knowing the buoyancy distribution and sum of total windage the designer can calculate/simulate which side of wind entry will give the best or worst underwing angle, which of course could be different for each design.

    BTW, on second thought I don't think aft wind will give exactly a venturi effect as I said earlier, but I do think aft wind will create under pressure and front wind will give over pressure under the bridge deck at least for some designs. The underwing angle could increase or decrease the lift problem depending on the design of the particular boat and which side is exposed.

    Cheers,
    Angel
     
  5. cavalier mk2
    Joined: Mar 2010
    Posts: 2,104
    Likes: 46, Points: 48, Legacy Rep: 214
    Location: Pacific NW North America

    cavalier mk2 Senior Member

    Ha, I've been waiting for you to make that post.....not many boats have that forward facing companion.....it does make me wonder how dry the cabin stays when you have to open the door during a cold, wet weather bash to windward. I like the Atlantic series though, when you get one send me a PM and I'll bring my Alaskan sweat suit (immersion suit) and help you put it to the test! Chris White has ridden out a few blows but I don't think he anchors by the stern.....
     
  6. Angélique
    Joined: Feb 2009
    Posts: 3,005
    Likes: 318, Points: 83, Legacy Rep: 1632
    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    Hmmm, in today's market, if we cough up $100K each and wait some time we might be able to buy this one together . . . :D

    It only needs a 49.4% price drop -- that happened before -- buyer :) -- seller :( --

    Does he do so after having considered the other option in regards to the lift we discuss here, or out of habit because most do so from mono tradition and for cockpit in cabin lee convenience . . ? ? - - (last only goes for a aft cockpit and companion way while anchoring from the bow)

    Cheers,
    Angel
     
  7. warwick
    Joined: Jan 2012
    Posts: 423
    Likes: 7, Points: 18, Legacy Rep: 63
    Location: papakura south auckland new zealand

    warwick Senior Member

    Doesn't the gun boat range use a forward cockpit. Another thing with the forward cockpit would be convincing the market, of its advantages. Most do not like change, or if coming from a mono hull they are used to a aft cockpit.
     
  8. cavalier mk2
    Joined: Mar 2010
    Posts: 2,104
    Likes: 46, Points: 48, Legacy Rep: 214
    Location: Pacific NW North America

    cavalier mk2 Senior Member

    For Chris White it is probably the reduced windage that keeps him anchoring off the bow as well as the lower noise from wave impacts. A transom is like the skin on a conga- I prefer my drums on shore!.A double ender might benefit from getting the anchor weight out of the bows....as usual there are lots of things that have to work together.

    One thing I like about the aft cockpit is you stay drier. The Searunners need a windshield on their center cockpit and after a comment Corey made I suspect the Atlantic series does too. I often see spray that would drench a center cockpit never make it aft on the Nicol.

    Going in halves on a Atlantic Angel? Does that mean we would have to agree where to go and take turns anchoring forwards and backwards? :)
     
  9. Angélique
    Joined: Feb 2009
    Posts: 3,005
    Likes: 318, Points: 83, Legacy Rep: 1632
    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    Yes Gunboat, but also some Lagoons and Bob Oram designs and SMG Multihull. Here's a discussion.

    Cheers,
    Angel
     
  10. Angélique
    Joined: Feb 2009
    Posts: 3,005
    Likes: 318, Points: 83, Legacy Rep: 1632
    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    First; I'm afraid so.

    Second; I suggest we measure the lift in a moderate storm and ask Chris White for his opinion about this.

    If it's not blowing so hard that flipping is a concern I'm in favor of having the cockpit on the cabin lee side at anchor unless it's very hot.

    Cheers,
    Angel

    P.S.

    Btw, PNW and Europe are both closer to Oz than to each other unless we take the Northwest Passage to transfer the boat sometimes. How's the melting of the ice, is the it OK there for a plastic Cat yet ?
     
  11. warwick
    Joined: Jan 2012
    Posts: 423
    Likes: 7, Points: 18, Legacy Rep: 63
    Location: papakura south auckland new zealand

    warwick Senior Member

    Or may be a pod catamaran, with double ended hulls or narrow transom. With a pod shape like an old long range fuel tank from a plane. With side access. only problem very little accommodation.

    it would have very little air resistance.
     
  12. oldsailor7
    Joined: May 2008
    Posts: 2,097
    Likes: 40, Points: 48, Legacy Rep: 436
    Location: Sydney Australia

    oldsailor7 Senior Member

    Cav said:- " The Searunners need a windshield on their center cockpit."

    Since I sold Searunner plans and experienced builders and sailors of these Tris, they were excellent boats ----but their achilles heel was their wet cockpits and the need to keep the aft cabin hatch shut tight in rough seas.

    You can't beat a nice protected cockpit behind an aft cabin hatch when beating to windward in choppy seas. :D
     
  13. Angélique
    Joined: Feb 2009
    Posts: 3,005
    Likes: 318, Points: 83, Legacy Rep: 1632
    Location: Belgium ⇄ The Netherlands

    Angélique aka Angel (only by name)

    I see the windshields also on SMG Multihull center cockpits.

    _SMG_Multihull_windshield_on_center_cockpit_1_.jpg - _SMG_Multihull_windshield_on_center_cockpit_2_.jpg
    - click pics to enlarge

    And a A-frame mast, now we might have Brian here ;)

    Cheers,
    Angel
     
  14. Corley
    Joined: Oct 2009
    Posts: 3,744
    Likes: 175, Points: 63, Legacy Rep: 826
    Location: Melbourne, Australia

    Corley epoxy coated

    If you have a look at the Three Peaks Video of Peccadillo you can see conditions in the front cockpit under extreme conditions on an Atlantic 46 catamaran. In the video the true wind speed was 40+ knots and they experienced gusts up to 60 knots. The owner swears by the front cockpit for sail handling and the vision it gives you while sailing and is willing to put up with it's "wetness". In moderate conditions it's quite dry though.

    http://www.boatdesign.net/forums/multihulls/three-peaks-race-video-peccadillo-43219.html
     

  15. cavalier mk2
    Joined: Mar 2010
    Posts: 2,104
    Likes: 46, Points: 48, Legacy Rep: 214
    Location: Pacific NW North America

    cavalier mk2 Senior Member

    Hello Angel, the North West Passage would take careful planning and luck with the weather, I'd really hate to be cold for that long!

    I'm all for testing but I can't find the 100 grand I buried out back.....as a former gub runner my finances might be scrutinized by various agencies. Gubs are small invisible creatures that can pretend to be anything in demand-guns, contraband, chains for politicians. I worked hard to finance the liberation of Cascadia from the yoke of corporate tyranny but I made the mistake of letting the Gubs hide the money......This is why I sail a Nicol but a funny thing happened on the way to the forum....I really like the Vagabond MK2! I'm also getting closer to finishing the new layout.....I'm a little concerned also that if we get into a big fight we will have to saw the Atlantic in half down the bridge deck and make 2 outriggers. This is not beyond my skill set but these things should be considered. The location issue may not be a problem....the Gubs may have worn out my welcome.

    Cheers, Cav
     
Loading...
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.