Camber

  • 28 Sep 2020 15:11
    Reply # 9269582 on 9266517

    Again, I instinctively prefer Paul's Aerojunk design for it's simplicity of construction, and the smoother less scalloped camber, and potentially adjustable camber (when raising the sail).   Like the soft wing sail, it is on the outer fringes of what could be called a "junk rig", as it doesn't have individual panels separated by battens, but rather an insect like exoskeleton.  Perhaps it should be called the Arthrojunk ;-).  It entirely eliminates this technical aspect of sail design, makes it possible to fairly easily optimizer camber throughout the sail if you are not satisfied with it initially.  Rip stop and abrasion would be my only concerns.  It would be interesting to see the relative performance between comparable Aerojunk and Split Junk, and Camber Panel junk on identical boats.   Performance taking in more than just speed and pointing ability.   There seem still to be folks who feel that the original Hassler style flat panel junk rig is the most reliable for voyaging.    I don't agree.

                                                                        H.W.

  • 28 Sep 2020 14:52
    Reply # 9269537 on 9269465
    Anonymous wrote:

    Again a biologist asks without understanding himsef: Why would the 90 deg shelf be more easily "lifted" from the bottom edge than it would be from the top edge of the panel?


     It seems pretty obvious to me...The 90 deg shelf will not only contain more fabric (weight), but will sag downward further.  The 45 or 30 will hang closer to it's inflated shape when there is no wind.  At least that's how I see it.
  • 28 Sep 2020 13:54
    Reply # 9269465 on 9266517

    Again a biologist asks without understanding himsef: Why would the 90 deg shelf be more easily "lifted" from the bottom edge than it would be from the top edge of the panel?

    Last modified: 28 Sep 2020 13:55 | Anonymous member
  • 28 Sep 2020 12:53
    Reply # 9269401 on 9269210
    Mark wrote:

    Just a thought on shelf angles.  A 90 deg shelf may not works so well in light winds for the top side of a panel, but I suppose it may not be an issue with the bottom edge.  So why not have a 45deg top edge and a 90deg bottom edge.  I know this sounds a bit weird and you guys may have an issue with looking different from the crowd !!

    I've had the same thought at times, but have never tried it. I see no reason why it wouldn't be effective, though.
  • 28 Sep 2020 10:36
    Reply # 9269210 on 9266517

    Just a thought on shelf angles.  A 90 deg shelf may not works so well in light winds for the top side of a panel, but I suppose it may not be an issue with the bottom edge.  So why not have a 45deg top edge and a 90deg bottom edge.  I know this sounds a bit weird and you guys may have an issue with looking different from the crowd !!

  • 27 Sep 2020 20:20
    Reply # 9268317 on 9268050
    Howard wrote:

          There is a saying we've all heard to the effect that sailing is about working on your boat in exotic places....

         

    Well, happily I can report that for all the years of sailing I have done, and to many exotic South Pacific destinations, I have never had to do any thing other than routine maintenance on my yachts. This probably as a result of well set up, relatively simple systems, and said scheduled maintenance checks. My observation of other cruising yachts is that it is the mechanical and electrical systems which are more likely to cause maintenance and reliability problems, rather than the rig. So whether a yacht is bermudan or junk rig, it is the potentially complex systems within the hull which are more likely to detract from cruising pleasure.

    I was a little astonished when recently selling my last yacht, that two of the parties who were very keen on the boat, did not purchase in the end because the boat did not have an electric anchor winch. I tried to explain that it really was very easy to retrieve the anchor by hand, given the weight of the boat, and the weight of the anchor gear. but no, too much hard work for them. Similarly with dinghies and outboards. I enjoy the exercise of rowing, even on a hard to row inflatable dinghy, and generally cannot be bothered with the complication of an outboard for the dinghy.

    Anyway, we should stick to the topic of camber!


    Last modified: 27 Sep 2020 20:40 | Anonymous member
  • 27 Sep 2020 17:11
    Reply # 9268050 on 9266861
    Anonymous wrote:
    Howard wrote:

      Why anybody sets to sea for extended voyaging with a modern Bermuda rig when a free standing cambered junk rig is available escapes me entirely, knowing that you will have to invest the cost of a new car in sails and rigging every 10 years or even less.  

        

    I think you need to be careful about making such sweeping statements, and I say this as someone who is a big fan of the junk rig, and have also crossed oceans with both junk and bermudan rig. Yes, my preference now is for a junk rig for reasons of simplicity, ease of handling, and use of low technology. But I have also done many thousands of miles of ocean cruising with a bermuadan cutter rig, and have delivered cross ocean numerous yachts with differing iterations of the bermadan rig, and I have found them to no less reliable, and generally no more difficult to handle than the equivalent sized junk rig if well set up with quick reefing. This is where the cutter rig is so good providing a range of sail area and combinations from 3 basic sails.. The problem with the modern bermudan rig is that too much complexity is creeping in, which means big money. But a bermudan rig boat is no more likely to need new sails than a junk rig boat. My last bermudan rig boat still had her original 30 year old sails which were in excellent condition because they were always covered when not in use.

    I would have preferred to have a junk rig on my new catamaran, but for reasons of weight that is not possible. Instead I have designed something of a hybrid rig, revisiting the gaff main, and using low technology fittings, lashings, and fiber rigging. What hardware I do need such as boom gooseneck I am making myself using carbon fiber, which as a raw material in small quantities is not expensive. The headsail will be self tacking to make handling easier. It is all a bit of an experiment so it will be interesting to see how it works out. But I wanted to use lessons learned from my previous junk rig to come up with an efficient, relatively inexpensive, and low technology bermudan rig.

    Of course the bermudan guys have just figured out that a way to make the rig more efficient is to get more sail up high, hence the proliferation of square top mainsails. Unfortunately to make this work a lot of expensive hardware is required. This is where the simplicity of the junk rig, and possibly variations of the gaff rig, for those who cannot, or choose not to go to the junk rig, can provide an alternative.   

    David:

           Broad brush statements are as you point out not wise.....  The vast majority of world voyaging boats are Bermuda rigged.  

         I'm not one of those people who have faith in lady luck.  She often smiles on me, and usually comes through when I need her most.    

         I look at things from a different perspective than many people, and that is one of the reasons I don't live from crisis to crisis.   The standing rigging on a Bermuda rig always looks like a veritable house of cards to me.   I know all about metal fatigue, and intergranular corrosion and such having fixed various systems for myself and other people all my life.  All those cables and hardware may inspire confidence in some people, but what I see is a system where failure of almost any one of dozens of seemingly insignificant parts can send the mast over the side.   I'm also a pilot, and helicopters scare me for the same reason.  Every component of the rotor system has a specified service life after which it MUST be replaced regardless of apparent condition.  Sailboats don't fall out of the sky killing all on board if something fails, but it is enough of a concern that replacing standing rigging on a fairly regular basis, in some cases at a cost comparable to a new car is called for.

        Clearly a well maintained Bermuda rig is safe and reliable. Most sailboats spend nearly all their time in a slip with the sails either covered or off stowed below extending life.   I'm very aware of UV degradation of fabric...(aircraft again).  The equation changes when a boat spends much of it's life actually voyaging, and even those spend far more time at anchor than sailing.  The stresses on a sail that uses the outhaul and vang to pull tension on the sail to shape it, and is supported only at the luff and foot are considerable, and any tear is likely to wipe the entire sail out.  The nature of sail design means that you are locked into a system where expensive fabrics are needed and skilled designers and seamsters to give it the shape and structure necessary.   That means that when you blow out a sail in the Indian Ocean and limp into Reunion for example you have a crisis that involves trying to contact a suitable sail maker in Europe or the US, arrange payment of thousands of dollars, and go through the nightmare of importation paying agents on both ends as well.   not to mention freight, and being stuck somewhere you may not want to be for months.  Numerous pieces of necessary hardware from sail track and cars, to traveler, winches, furling gear, etc, also represent maintenance issues.

          There is a saying we've all heard to the effect that sailing is about working on your boat in exotic places....

         Presumably you made your own sail for the junk rig, and can do it again or direct a local seamstress in doing it for/with you from locally available materials.  Likely you only lost one panel, so "limping in" meant tying two battens together, and if you tore one panel, your repair at sea is far more likely to hold over a long period due to lower stresses. Your mast is the single "failure point", not dozens of bits of hardware and cables. That is only one thing to worry about and inspect, and you quite likely built it yourself and can do it again from locally available lumber. Your complement of hardware and rigging is small enough that unlike a Bermuda rig, you can carry enough spares and repair materials to get you through.  

           Clearly I don't think like other people ;-)   In cars I look at things like turbochargers, overhead and variable cam timing, traction control and antilock brakes ,electric windows and seats, self parking, lane following, and numerous other "features" as liabilities ... just things to maintain and to fail.     I like simplicity and maintainability, weather we are talking about a boat or a car.  

         This photo says it all..... he was still sailing.


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  • 26 Sep 2020 21:10
    Reply # 9266861 on 9266517
    Howard wrote:

      Why anybody sets to sea for extended voyaging with a modern Bermuda rig when a free standing cambered junk rig is available escapes me entirely, knowing that you will have to invest the cost of a new car in sails and rigging every 10 years or even less.  

        

    I think you need to be careful about making such sweeping statements, and I say this as someone who is a big fan of the junk rig, and have also crossed oceans with both junk and bermudan rig. Yes, my preference now is for a junk rig for reasons of simplicity, ease of handling, and use of low technology. But I have also done many thousands of miles of ocean cruising with a bermuadan cutter rig, and have delivered cross ocean numerous yachts with differing iterations of the bermadan rig, and I have found them to no less reliable, and generally no more difficult to handle than the equivalent sized junk rig if well set up with quick reefing. This is where the cutter rig is so good providing a range of sail area and combinations from 3 basic sails.. The problem with the modern bermudan rig is that too much complexity is creeping in, which means big money. But a bermudan rig boat is no more likely to need new sails than a junk rig boat. My last bermudan rig boat still had her original 30 year old sails which were in excellent condition because they were always covered when not in use.

    I would have preferred to have a junk rig on my new catamaran, but for reasons of weight that is not possible. Instead I have designed something of a hybrid rig, revisiting the gaff main, and using low technology fittings, lashings, and fiber rigging. What hardware I do need such as boom gooseneck I am making myself using carbon fiber, which as a raw material in small quantities is not expensive. The headsail will be self tacking to make handling easier. It is all a bit of an experiment so it will be interesting to see how it works out. But I wanted to use lessons learned from my previous junk rig to come up with an efficient, relatively inexpensive, and low technology bermudan rig.

    Of course the bermudan guys have just figured out that a way to make the rig more efficient is to get more sail up high, hence the proliferation of square top mainsails. Unfortunately to make this work a lot of expensive hardware is required. This is where the simplicity of the junk rig, and possibly variations of the gaff rig, for those who cannot, or choose not to go to the junk rig, can provide an alternative.   

    Last modified: 27 Sep 2020 05:36 | Anonymous member
  • 26 Sep 2020 17:10
    Reply # 9266567 on 9266517
    Anonymous member (Administrator)
    Howard wrote:

    .....  It seems that hinged battens also have fallen from favor... though are still in use and being improved upon.  The fundamental problem I see with them is that in theory at least, they should give you max camber when you want minimum camber and minimum camber when you want maximum. 


                                                                H.W.

    Howard,
    I am afraid you got this slightly wrong. Unlike bendy battens, the hinges in the hinged battens go to their stops each time you tack, and that happens regardless of wind strength  -  or at least mine did. On my Malena, on a calm day, I could just choose which side to sit on. The slight heel of the boat was enough to make the sail swing out and the hinges to go to their stops. I had a couple of spectacular light-wind stunts as a result of this. See NL 24.

    My reason for dropping the hinge method of making camber, was mainly that the max camber had to sit further aft than I liked (to avoid s-bending of the hinges). This lead to increased weather helm compared to a flat sail (and even more compared to a cambered-panel sail). On cambered panels I am freer to move the max camber point (and thus the CP) more forward.

    Cheers,
    Arne


  • 26 Sep 2020 16:27
    Message # 9266517

    I've enjoyed reading the current thread discussing broadseaming, versus shelf foot, straight or angled shelf, etc.   An excellent and informative thread.

    I personally am attracted to Paul McKay's approach in which I see a lot of advantages... at least from my perspective, along with a few disadvantages.  It seems that hinged battens also have fallen from favor... though are still in use and being improved upon.  The fundamental problem I see with them is that in theory at least, they should give you max camber when you want minimum camber and minimum camber when you want maximum. Simple logic says that wind pressure is going to induce camber.  Though there have been statements made to the contrary, I find them difficult to reconcile with logic and reason. 

          Evolution of the junk rig, setting aside the soft wing sail which I don't consider really fits the category, but rather has evolved from it... as well as from outside, seems not to have much room to progress in any dramatic ways at this point.  Just incremental improvements getting ever smaller with less reward for the effort and expense as we move forward.  But that is the nature of most progress.  Look at the Bermuda rig for example.  In my book simplicity wins out over complexity nearly every time.  The split rigs have taken the junk rig to the next level where the performance advantages of the Bermuda rig forward of a beam reach are small enough to be far outweighed in real world non-racing sailing by the ease of handling the junk rig, not to mention the lack of the outrageously complex and expensive standing rigging with all of it's myriad potential catastrophic failure points.   Why anybody sets to sea for extended voyaging with a modern Bermuda rig when a free standing cambered junk rig is available escapes me entirely, knowing that you will have to invest the cost of a new car in sails and rigging every 10 years or even less.  

         I'm sitting here at my desk just thinking about these things watching the trees outside being laid over by gusts I'd estimate at around 50kts... a very wild day with a front passing through with violent winds.  I'm giving thanks that I had the trees trimmed away from my power line just a couple of days ago. Most of a day's work processing and disposing of the branches.   I'm glad I'm not sailing today ;-)


                                                                H.W.

       " ...there is nothing - absolutely nothing - half so much worth doing as simply messing about in junk-rigged boats" 
                                                               - the Chinese Water Rat

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