Aftmast rigs???

Discussion in 'Sailboats' started by jdardozzi, May 28, 2002.

  1. CT249
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    CT249 Senior Member

    So two designers having done boats with unusual rigs proves what, may I ask?

    Sure, the two owners expressed happiness with the rigs - so what? There are also people who claim that cat rigs are best, that solid wings are best, that junk rigs are best, that masthead cutters are best. The fact that two people like vaguely similar rigs is no evidence of superiority.

    Quite a few of the other links you've posted include information that is obviously incorrect. For example, very early in this thread you posted a link that claimed that conventional rigs were encouraged by handicap rules that supposedly limited mast rake. That is obviously incorrect since there are no such rules, and there are many classes that do not use rating rules but still use conventional sloop rigs, because they have been proven faster by decades of real-life experience. There was also a link to an article that claimed that a 30' production boat had been re-rigged and went twice as fast as its sisters - if true, that 30' production boat would be several knots faster downwind than Wild Oats XI, Comanche and all the other 100 foot supermaxis........

    Since there are issues of that sort with the evidence that has been given to show the claims about the mast-aft rig, there is reason for scepticism.

    And by the way, can you please explain how acceleration in a gust alleviates the extra loads created by the gust when a boat is sailing upwind?
     
  2. brian eiland
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    brian eiland Senior Member

    I don't think I ever made reference to the rating rules limiting mast-rake. Perhaps you could find that quote for me?


    Again I do not recall such a claim by myself.
    I did mention a Out Island ketch rig that upon removal of its mainsail, it cut its leeway in half, and subsequently inserted a staysail in the place of that mainsail, regained the 1/2-1 knot it had lost to the removal of the mainsail.

    And I did mention a Hall experiment where their uni-rigged J-boat vessel faired better upwind with the addition of a genoa.

    So perhaps you can also find this 'mistaken quote' I made??




    Its know as the conservation of energy. If a vessel (or whatever) gets hit by a energy force (lets say a blast of air), that body can relieve itself of some of that added energy by accelerating. Some vessels can accelerate faster than others. Some vessels that can't, must sit there an absorb the brunt of the energy input in other ways.

    I was saying that a multihull vessel can accelerate more easily than the ballasted monohull, thus the accelleration is a means of 'alleviating a gust of wind'.

    You have turned it into just an upwind condition. I was not speaking to just an upwind condition, but rather a broader range of wind directions. Besides when we are competitively sailing upwind we don't always slack off our mainsail's head to relieve the gust, but rather we momentarily point up a little higher (luff up),...don't we??
     
  3. brian eiland
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    brian eiland Senior Member

    Superiorty

    I think we have to reconsider this word 'superiority'. Does it just involve a speed claims, or windward claims, or are their many other handling aspects that can make one rig superior to others for it's operator, particularly if that operator is shorthanded, etc. ??
     
  4. CT249
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    CT249 Senior Member

    /\

    The incorrect claims come as early as your post 14 on page 1 of this thread. There you quoted a website that claims "Ever since 1851 when the Schooner America with her 11.5 degree mast rake won the America's cup, mast rake has been used to improve the performance of sail power as a propulsion method. Every high speed craft including land yachts, ice boats, windsurfers and racing Multihulls use mast rake to improve performance."

    That claim is simply bollocks. high speed craft such as Moths, A Class and C Class cats and ORMA 60s do not carry unusually large amounts of rake. The same site claims that "Yachts that race to a handicap don't use mast rake because it is penalized by the handicap rules" which is equally silly and equally wrong.

    Other claims you've linked to in this and other discussions are just as wrong. I admit that because one of your links died (which is not your fault, it was very old) I wrongly thought that it was you who had claimed that a wingmasted 30 footer was twice as fast downwind as a sloop rigged sister; I got to that claim by reading a post from someone else you had linked to, and I got my Erics confused (and while I understand that may be an obscure reference, it won't seem as disrespectful as if I had explained it further). While it wasn't a claim you had linked to directly, it was another example of the complete over-hyping of 'alternative' rigs /on this forum, which as usual carried with it the implication that those who preferred 'conventional' rigs were stick-in-the-mud idiots.

    To come back to the post that spurred me to re-enter this thread, the fact is that a quote of a '70s copy of a magazine design article doesn't prove anything about the claims made for mast-aft rigs. And I do take issue with the insinuation, which you made in that post and which has liberally flavoured so many posts on this and similar subjects, that it's conservatism that is leading some people to discount this sort of rig.

    There are many people in the sailing world who grew up in scenes where innovation was pretty common - where people would grab a bit of foam or wood and hack at it because we had what we thought was a good idea, or to see where we could take a 'proven' good idea (in my case with speed windsurfers, I took it WAY too far). This lead to scenes where kid's boats had wingmasts, where people had hulls that were one foot wide, or where working-class kids in their early 20s won trans-ocean races with boats they built in their yard from spare parts and cheap wood....or where carpenters even today keep on scaring America's Cup pros with home-made kit.

    When seen from this perspective, the continual insinuation that people reject bright ideas because of conservatism is just plain factually wrong, as well as insulting. The sport of sailing has arguably seen more "advances" than just about any other in recent decades. It couldn't do that if it was full of stick-in-the-muds.

    Sailors (or at least, sailors from some areas) leap at bright ideas most of the time, and to fall back on conservatism as an excuse for why they reject designs (as is done so often on this board and this thread) is arguably insulting and wrong. Using the "people are too conservative to see the brilliance of the idea" card can be seen as a cheap and easy way to avoid reasonable discussion.


    PS - acceleration in a gust will not just increase rig loadings when a boat is going upwind - it would also do it when a reasonably fast boat is reaching. And being overpowered upwind due to excessive headstay sag is much more of an issue than being overpowered downwind, most of the time.

    In the interest of balance, I've noted in this thread or another on BDF that many one designs do sail well with headstay sag, but they also generally work quite hard at compensating for it.
     
  5. CT249
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    CT249 Senior Member

    Sure. I haven't discounted the fact that the mast-aft rig may work for some people. Personally I don't trust furling jibs that much, but because I prefer other rigs I haven't had that much experience with them so I may be wrong. I also fail to see why a headsail flapping around is better than a main controlled by a boom (or wishbone), but maybe I'm too used to short passages and sailing rather than motoring or motorsailing.

    What some of us take issue is is not the idea that a particular rig may work for some people in some situations (I own rigs to half a dozen different designs and each works for a particular situation) but the claims that are made for the superiority of the rig in particular aspects, or overall. For example the information about the claimed efficiency of 'clean' jib luffs does not seem to stack up in the light of thousands of experiments with racing craft and the theoretical/scientific information we can get from people like Tom Speer and Mikko here.

    The attempts to use dubious claims about racing to bolster the claims for various rigs are another thing we take issue with. Re-reading the thread, I saw that converted Formula 40s with their big headsails were used as evidence of the superiority of headsails.

    Oh, nope. When F40s had to race with a particular measured area, they used the minimum jib size that was allowed under the rules (a storm jib, which they were required to carry anyway). They only grew big headsails after the F40 class dies and some of the boats were bought for racing on the Swiss lakes under the particular rules and conditions of Swiss lake racing, where sail area was effectively unrestricted and there were long periods of almost calm winds. The much bigger headsails that they grew then were not efficient for their area IIRC, but they were very, very big, and that was what counted. They were not an advertisement for the superiority of headsails - they proved that if you increase your sail area by about 400% by whacking on a big jib, you go a fraction faster. From many angles, that is not efficiency in action.

    In short, people like me are not necessarily claiming that a particular rig is not good for certain people in certain situations - we're calling BS on the evidence behind some claims, and on the claims that particular rigs are better per se.
     
  6. RHough
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    RHough Retro Dude

    Please not that this was the *FIRST* reply in this thread and still the proponents of the aft-mast and other wing-nut rigs have failed to respond with data. Lots of hype and warm/fuzzy "local yokel built one and says it is the best" type stories cited as if they are credible evidence of performance claims.

    A mast creates drag.
    A sail creates drag.
    If the sail is set from a stay the stay creates drag.

    When the stay is forward of the mast the drag from the stay&sail and the drag from the mast add together.

    When the sail is set behind the mast. The sail *REDUCES* the drag of the mast and the total drag of the rig is lower.

    Until that bit of physics gets proved wrong no one will believe claims that aft mast rigs are even as good as a conventional rig, much less better.

    The "clean luff" vs sail behind a mast claims of better performance are simply wrong. An extreme rig with small main and large masthead genoa has the same loading as an aft mast rig. The boom, leech, and mainsheet act exactly like the backstay and jumper strut of aft mast rigs. This end of the IOR era sail plan is still better than the aft mast rig because the main acts like a fairing to reduce the drag from the mast.

    Sailing efficiency is all about lift and drag. Efficient rigs allow craft to sail faster than the wind or closer to the wind. Efficient rigs have higher ratios of drive to heel.

    If the aft mast configuration was anywhere near as efficient as a conventional rig some nut-job in a barn somewhere would have built a ice boat, land yacht, or racing dinghy to prove the rig's performance. I'm almost certain that the proponents of odd rigs on this forum have spent countless hours searching for such evidence to back their claims ... in twelve years (12) not one wing-nut rig advocate has had a response to the second post in the thread.

    Fast sailing craft and racing dinghies are where good rigs get developed. Racing dinghies are much like cruising sailboats. The rig must be easy to handle for the area and it must be adjustable for conditions. Good rigs point higher or sail faster with less heel. Those are selling points for cruising. Good rigs drive the boat faster thus reducing passage times as well as winning races. Good rigs are easy to adapt to conditions. Being able to sail well in a wide range of conditions without having to change sails or reef are virtues in racing boats as well as cruising boats.

    What rigs do Ice Boats use?
    What rigs do Land Yachts use?
    What rigs do skiffs use?
    What rigs do fast multi-hulls use?

    None of these craft hang a reject crane from a construction site off the transom and roll up sails on the guy wires ... there is a reason.

    Read this again:
     
  7. gggGuest
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    gggGuest ...

    To be sort of fair to the 'less load on the rig' myth believers (assuming that's what we're talking about, I fear I don't manage to read all posts on this thread in detail) some very competent sailors have fallen for it. I heard tell (this is secondhand I admit) that Lawrie Smith held the belief that when running or deep reaching having more sail up and thus increasing speed reduced the apparent wind [true] and therefore reduced the loads on the rig [complete nonsense]. In the tale I heard the source was on a Whitbread 60 deep in the Southern Ocean with heavily reefed mainsail and storm spinnaker when a certain competitor careered past under full rag. It was with no surprise at all, I was told, that on the next 24 hour schedule they heard that the boat in question had put the rig over the bow...

    You'd think common sense would let folk know that if the boat is pushing much more water out of the way at a greater velocity the total loads on the rig must be increased, but its amazing how much we humans can deceive ourselves by crazy theorising...

    I have seen it tried... I forget which boat it was and who was responsible [for which the gentleman concerned is probably very grateful], but I'm sure that, I think in the mid 80s, I saw a racing dinghy prototype configured with an aft mast style rig. To call the result a dog would be unfair to canines everywhere, because even a pekinese with arthritis was faster.
     
  8. brian eiland
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    brian eiland Senior Member

    I think you should probably go find another subject thread to contribute to until you learn a bit more about this subject, have you ever raced a fast multihull boat? Do you really understand tacking (gybing) downwind on a multihull verses running downwind??

    At least R Hough and CT249 put up some intelligence in their postings.



    Perhaps you were referring to a pretty well known and prolific designer known as Phil Bolger? I made a small reference to only one of his books back on posting #266 , Boats with an Open Mind

    BTW, click on that 3rd PDF, and read the "Author's Notes" about his mast aft experiment
     
  9. brian eiland
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    brian eiland Senior Member

    Phil Bolger

    http://en.wikipedia.org/wiki/Phil_Bolger

    Philip C. Bolger (December 3, 1927 – May 24, 2009), prolific boat designer, was born and lived in Gloucester, Massachusetts. He began work full-time as a draftsman for boat designers Lindsay Lord and then John Hacker in the early 1950s.

    He used traditional rigs, from a the simplest "Cat rig" (single sail) through sloops, many yawls and schooners at a time when almost all other designers were concentrating purely on racing rule derived sloops. The diversity of rigs was accompanied by a broad spectrum of sails including the sprit-boomed leg of mutton, the sprit sail, the gaff sail, the lug sail and the lateen in addition to the classic Bermudan/marconi rig. His book '100 Sailing Rigs "Straight talk"' later reedited as '103 Sailing Rigs "Straight talk"' provides a fascinating look at both rig configurations and sail types as well as his insight into a subject in which he was undoubtedly an expert.
     
  10. sharpii2
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    sharpii2 Senior Member

    It seems that the notion that what is best for the racers is best for everyone is quite an item of faith with you.

    What I'm hearing a lot of, in this thread, is that a lot of people want to get rid of Bermudan Boom. I can see good reason for this. The Boom on a modern Bermudan rig has a great deal of sail on it for its length. It can swing over with a quickness and pack a mighty wallop for anyone who gets in its way. For this reason, it is usually set up reasonably high, so it's less likely to crack sculls. Being placed higher over the cockpit sole makes it harder to reef. At least this is the argument I'm surmising.

    Though I agree with you that the more conventional Bermudan rigs are probably faster, I don't entirely agree with your reasoning on why this is so.

    The argument, that the sail behind the mast reduces the drag of the mast, seems to assume that the mast is designed to have a sail behind it. In this case the width of the mast (the fore and aft dimension) must be limited, so it doesn't compromise reaching ability (for slower boats that don't have a lot of apparent wind effect) too much. If the mast is designed to have no sail behind it, it can be much wider and well tapered aft.

    My theory is that the more conventional rig is faster because it carries more SA per given amount of spar and rigging.
     
  11. CT249
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    CT249 Senior Member

    /\

    Without wanting to speak for Gggguest, I think it's fair to say that he has probably been tacking downwind at speed for 30 years or more.

    Bolger boats are interesting (I'd like a Folding Schooner as a fun boat) but exactly why Bolger is relevant to a post about racing dinghies is something of a mystery to me - what were his qualifications in the field of racing dinghy design? I can find no indication of a Bolger design that would qualify as fast - I see that his Martha Jane 23 has been given a staggering PHRF of 425 at one club....truth be known, I didn't think there were any PHRF ratings over 400!

    The Light Schooner, a 23' open boat, is rated down here at about the same speed as 16 foot long ply cabin cruisers from the '60s, and much slower than the Norwalk Island Sharpie 23 and 18, which are shorter than the Bolger and have full accommodation. So even when compared to other home-made split rigs, the Bolger design is normally slow.

    The idea that Bolger, who was working in an area where development dinghy designs were extremely rare*, would know more about such things than people do in areas where development-class dinghies can be found in their hundreds is a pretty odd one. What made Bolger so much smarter than the Brits and Aussies that he could come up with better ideas in isolation?

    However, if people want to say that Bolger knows more than guys like Morrison (who has designed thousands of racing dinghies and hundreds of individual boats) or Bethwaite and the dozens of other development-class designers they interact with, then it's interesting to read Bolger's remarks on the staysail rig he created;

    "The (staysail) boat was consistently outsailed by several boats of the same class with the original 1921 jibheaded cat rig. The staysail cat rig's geometry requires a smaller sail for any given mast height than a jibheader. This is supposed to be compensated by improved aerodynamics in the staysail, but it wasn't...the boat showed occasional flashes of close-winded speed (but) neither of us could make her do it consistently. (The staysail rig) needs phenomenal skill and concentration. The perfect airfoil of the staysail must be extremely prone to stalling.....no more power than a sail stalled by mast interference."

    Since it sounds as if Bolger concluded that the staysail rig did not live up to theory!

    * just to make it clear, many US sailors have done great development work, but the fact is that development classes are much less popular in the USA than in some other countries.
     
  12. CT249
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    CT249 Senior Member

    And that theory is neatly demolished by the fact that classes that restrict total sail area, but allow unconventional rigs, normally choose either a 'conventional' rig or a mono rig.

    At least one class has so few restrictions that a windmill rig was legally allowed to race. That class is now completely dominated by boats with a high aspect sloop rig, because it's faster even when there are effectively no rules about how the permitted sail area is used.

    Development classes that limit spar height also tend to go for 'conventional' rigs. Development classes that don't limit sail area or spar height go for
    'conventional rigs'.

    Pretty much no matter what the ruleset, 'conventional' rigs or cat rigs are favoured. And when the headsail-only rig has been tried in competition (as with Vendredi Trieze) it has basically failed.

    Let me make it clear that I'm not saying that the best racing rig makes the best cruising rig (although that may well be true for many people) but the lessons of racing rigs shouldn't be ignored. And the fact that many people make up rubbish to explain the general preference for conventional rigs (like "rating rules prevent rake") does tend to obscure the reality.
     
  13. gggGuest
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    gggGuest ...

    Ok, I admit it, you've found me out, I've never done any apparent wind sailing in my life...
     
  14. RHough
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    RHough Retro Dude

    And poor performance for cruising is your holy grail. :)

    What are you on about? No one. No one. No one sails at angles where the boom "swings over with a quickness and mighty wallop". Well maybe clueless cruisers do ... lord knows I've repaired enough broken booms to know that clueless and cruiser both start with C. :)

    The height and ease of reefing are not related at all. Low booms and proper boom crutches are part of easy to handle rigs.

    Wow ... have you not read anything that rig designers have posted?
    Please *show us the numbers* show what mast profile that is "much wider and well tapered" and roller furling stayed sail will have less drag than the same area set behind the mast.

    The fore and aft rig allows fewer crew for a given sail area. More area, easily controlled equals safer boats. Fewer crew equals greater profits.

    The same goals drive the design of cruising rigs, working sail, and racing. Greatest power/speed for least effort.
    What? There is no direct relationship between the center of area and heeling force.
    No.
    Assuming we are talking about displacement hulls that are speed limited by waterline ... Once "hull speed" is reached the rig can be de-powered. Every cruising boat rig I have ever seen or worked on has this ability. No expensive spars required. The most basic control is twist. That is why the SA height and heeling forces are not related.
    What did you miss? If you know how to de-power your rig without reefing it is easier to sail. Good for racers and good for cruisers. If you have to reef, a fractional sloop is pretty cool. No headsail change required for reef 1. At reef 2 you have a short masthead rig. Then you roll the jib and sail on with the reefed main. If you need to reduce area beyond that you need to fire your weather router or blame climate change.

    You have to be joking?
    You would trade sailing performance for good manners at anchor? Seriously?
    I owned a boat that had rotten (near psychotic) manners at anchor. She once wrapped the anchor rode around her keel. Ugly is too kind a word to describe it. All it took was a simple riding sail to make her sweet and happy at anchor. $106.20 for the kit. I assume any cruiser can sew it together. I did.

    Riding sail

    You cannot be serious when you suggest that for lack of a $100 riding sail you are going to change the rig.

    The bottom line is that good rigs, trimmed properly are fast and easy to sail. Much of the anti-racing rig posts on this forum refer to the IOR driven large overlapping masthead Genoa and small main rigs. Modern fractional rigs proved better even though the rule was not kind to them.

    Cheers,
    Randy
     

  15. sharpii2
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    sharpii2 Senior Member

    I never intended to to claim that a mast aft rig would be faster than a more conventional BR. And I never meant to disparage the racing crowd in any of my posts on this matter. But I do have to admit I get a little tired of their arrogance. To put things in a nut shell, I will state the five top virtues I would expect from a good racer. Then I will state the top five for a good cruiser.

    For a good racer:

    1.) seaworthy.
    2.) fast.
    3.) reasonably easy to handle.
    4.) reasonably low cost for its performance.
    5.) reasonably comfortable.

    For a good cruiser:

    1.) seaworthy
    2.) comfortable
    3.) easy to handle
    4.) reasonably low cost (including maintenance)
    5.) reasonably fast.

    Once we remove "sea worthy", look what ends up on top of the list for the racer, and at the bottom of the list for the cruiser.

    Notice that I use the weasel word "reasonably" three times for the racer, but only twice for the cruiser.

    The reason for this is that the prime requirement for a racer, above and beyond all others, except for seaworthiness, is speed. Everything else is a secondary consideration, hence the word "reasonable" ahead of it.

    For a cruiser, speed is often sacrificed for comfort, easy handling, and cost. I would expect the rig choice to reflect that.
     
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