A-frame vs single mast rig, loads & weight on a cat

Discussion in 'Boat Design' started by isvflorin, Nov 25, 2014.

  1. johnhazel
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    johnhazel Senior Member

  2. brian eiland
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    brian eiland Senior Member

    So what does this rig look like?

    Aren't there some sketches or drawings available?


    BTW have you seen this posting (test of an aft mounted A-frame mast with a couple of headsails)
    Wind tunnel and CFD investigation of unconventional aftmast rigs
     
  3. brian eiland
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    brian eiland Senior Member

  4. brian eiland
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    brian eiland Senior Member

    There are a number of good discussions and photos and drawings on the Wishbone subject thread.

    BTW, I'm the fellow who started that subject thread, and I labeled it 'wishbone' rather than A-frame as the original boat I was searching for had a wishbone shaped A mast.


    This fellow's site is still up, even after he has sold his boat. He has LOTS of experiences in dealing with these unusual rigs, including some unique manners of sail deployment depending on wind conditions.
     
  5. Gus7119
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    Gus7119 Senior Member

    Sorry to disagree. It depends on what side of the world you are from regarding your comment above. I find Europeans and Americans see anything under 40 foot as a small boat. 35-38 foot, obviously defendant on how many person on board is perfect for a couple or single to circumnavigate. Ive done deliveries al over Asia and around Australia on 30 - 3 foot cats with 5 people on most for the fun and company. Although I was the only one being paid and we did pitch pole we had great fun and were not spartan at all. It all depends cruisers want safety first and speed doesn't really come into it as theres no time frame usually.
    Id go for it pal a 35 ft is fine. And as for it not being a coastal boat. Gees what size do you need now as a coastal boat? Sailors have saile from Australia to Singapore in 18ft open boats. 20ft boats sail all over Australia every day so Im not sure what your reasoning is in making a judgement call on 35ft not really being a coastal cruiser.
    But with the rig as Im building a 38ft cat to circumnavigate at the moment and have done some reading and talking just grab a secondhand rig its a known entity and I can sail a 40ft boat all sails up single hand without an issue. If you have issues with strength and stuff spend what you save on electric winches and such to make it easy peasy for yourself if you find handling a problem.
    Cheers
    Gus
     
  6. Gus7119
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    Gus7119 Senior Member

    Thats offline. but a Guy in Oz built a 65 foot steel cat in the 70's and was the first to make a mast like this at the time it was the biggest cat in the world and the mast was amazing. The cat also had feet that allowed it to walk up a beach for anti fouling and repair powered by a vw engine. He reckoned it was kill and cheap to boot. He got the idea from antenna towers and welded it up himself. Have a look at the walking cat or catamaran that walks on youtube its great.
    This would be heaps cheaper but still carry the loads of a standard rig.
    I think alot of people are missing the point here. This guy seem to want to try something different there are users that say it works well and the loads not being carried in the center of the beam are a bonus for a cat. Id to a furling main with the two jibs even one.

    I must say I love the idea of the furling main and wishbone combo its a great idea. As furling masts are expensive and I havent looked at the furling boom but just love the idea of shrinking main to reduce sail without having to get up and reef the dam thing in a storm.

    And furlers are king not sure why anyone would have an issue with hem been sailing 40 years and when the became standard I enjoyed sailing even more.

    Cheers
    Gus
     
  7. brian eiland
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    brian eiland Senior Member

    Wonder how many Dick Newick owners might disagree with this statement. Or for that matter a number of early OSTAR participates. Or the number of Prouts or Wharrams that have crossed oceans. :rolleyes:
     
  8. brian eiland
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    brian eiland Senior Member

    Isvflorin, I find you willingness to explore the unusual refreshing . Too bad you were met with so many 'traditionalist' offering stale arguments.

    I must have been off on another pursuit when you introduced this subject thread, or I might have entered the discussion earlier. As it stands now I do not see any reason to argue some of the 'stuff' bought up here.

    Three cheers for not just accepting the 'given', and being bold enough to go out exploring options.
     
  9. Gus7119
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    Gus7119 Senior Member

    I started a new thread in the hope wed get more info from real life users but came across the same old argument traditional rigs are just better with no stats nor real life experiences sailing with it. And the old if its not on a racing boat why bother. Well because people who have used it have great things to say. We all love traditional rigs no one is denied that but there must be something better for cruising. And race boats and criusin4boats as totall5diffrent. Any way nice try shame you didnt go for it. I mean really one argent is the loads on the stays like a sloop rig doesnt have them.
    If you have anything other than its not on race boats the stays carry loads or the great the loads are in diffrent places please go to the following and let me know;
    http://www.boatdesign.net/forums/multihulls/frame-masts-54941.html#post763643

    Cheers
    Gus
     
  10. isvflorin
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    isvflorin Junior Member

    final version

    I didn't realize people are still responding here, I don't get notifications of posts for some reason, thanks for the comments. I believe the design is complete now and I don't want to work on changing things any further otherwise I will never end up building it. You can find more info on the project here.
    I expect a lot of criticism as usual, but I believe the project is much more conventional than initially envisioned, generally due to simplicity and lowering the amount of hardware and things to build.
    [​IMG]
     
    1 person likes this.
  11. upchurchmr
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    upchurchmr Senior Member

    So you went traditional.
    Looks a lot like a Prout mast placement.
    Gus might have some suggestions about how you obviously got it all wrong.

    Good luck with the boat.
     
  12. brian eiland
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    brian eiland Senior Member

    nice Aftmast Rig

    Very interesting. I'm glad you found you way back to your forum discussion.I tried sending you a private email, but that did not go thru. Then I tried a private message on the forum here, and possible you have not seen that.

    Anyway great to view your new info. You will find that I posted references to your vessel over on my aftmast subject thread, particularly as it came along very timely with some other discussions over there in reference to Prout type' aftmast rigs.
    http://www.boatdesign.net/forums/sailboats/aftmast-rigs-623-62.html#post763744
    I think the gentleman DennisRB will find your new rig very interesting as well.
     
  13. DennisRB
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    DennisRB Senior Member

    Gday isvflorin. I was worried that the criticism put you off, but I am glad you came back. I think the design is really great. I think the slightly more conventional, but also slightly unconventional rig is perfect. In fact the rig I personally thought would be best for your boat is pretty much exactly what you went with. Is the boom a little low to the passengers?

    [​IMG]

    The design is light with deep appendages so I would expect very good performance at all wind angles. Is there a reason you went with one dagger in the center rather than one offset in a regular hull other than symmetry?
     
  14. isvflorin
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    isvflorin Junior Member

    Brian, apologies, I see now that I have pm's, never checked as I thought I'd receive an email notification, I just missed looking at the message panel.

    Single centerboard vs anything else: I don't like a single centerboard, I don't like fixed twin daggers as they are a big safety concern. Anything that doesn't kick up is bad imho. Asymmetrical dagger in hull I don't like as it won't kick up and once you build it it is rather hard to change its position in case you want to adjust the balance of the rig and weather/lee helm. The compromise I've chosen I believe makes sense for this design, probably not for others. It kicks up, you can adjust it fore and aft without complicated mech and it won't take up space inside the hulls, you don't need unnecessary length to the board as the hulls are tall etc. Disadvantages ? It has to be bigger, higher loads, pivoting it still more mechanically complicated than trunks, takes some space in the center nacelle. For me it's worth the complications. Though the design is meant to be flexible. If someone wants to buy plans and build one, nobody stops them from having daggers inside the hulls.

    The boom is as low as possible, as the aft trampoline is not meant for any circulation. People will only be there on inflatable beds reading a book in nice weather. Circulation is done on the bridge walkway to go from port to stbd. There is no running rigging that needs attendance on the aft tramp.

    In regards to rigs - I believe that for a cruiser, to judge the suitability of a rig from a pure performance pov is dead wrong. Platform design has to be unified with the rig design, cost, loads and maneuvrability should be accounted for. Anyone suggesting a fractional sloop with a large main has too much money and also restricts the bridge design to moving everything aft (most of the time), moving weight aft as well. This is my humble opinion. Anyone suggesting a cat under 35ft is too small for whatever, most probably haven't considered budget. Talking about boats and not considering budget is pretty useless imho.
     

  15. brian eiland
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    brian eiland Senior Member

    Hi Isvforlin,
    I'm glad you got back to your subject thread. That is a real interesting and nice looking new rig you've drawn up.

    I feel that it now much more of an aftmast style rig than an A-frame one you started this subject thread with, and titled the subject thread with 'A-frame'. Since you have now moved on to a much different rig, and truly an aftmast type, I thought it was appropriate to recreate some of your latest dwgs and discussions over on a subject thread titled 'aftmast rig'.

    Here is that posting I made with your material. I hope you don't mind, as I feel it is much more appropriate to explore and discuss your rig in this other subject thread.
    http://www.boatdesign.net/forums/sailboats/aftmast-rigs-623-63.html#post764126

    I'll be contacting you by private email as well, if you don't mind?
     
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