Are we making any real design improvements??

Discussion in 'Sailboats' started by Wardi, May 3, 2004.

  1. Wardi
    Joined: Nov 2003
    Posts: 161
    Likes: 1, Points: 0, Legacy Rep: 15
    Location: Sydney

    Wardi Senior Member

    A short quote from an interesting article in a local sailing magazine - Afloat:
    http://www.afloat.com.au/external files/0504_Yesteryear.pdf

    W (Billy) Hughes asks:
    Are today’s lightweight ‘sea skiffs’ really better than the yachts of half a century ago?

    His yardstick for measuring yacht performance is the Rhodes designed yawl Margaret Rintoul. She broke the record from Sydney to Hobart in 1951.
    Her elapsed time of 4 days, 2 hours, 29 minutes, 1 second,(98.483 hours) gave her an average speed of 6.37 knots.

    For a waterline length of 32ft she achieved a speed/length ratio of 1.126.
    The front runners in this year’s Hobart race were :-
    Yacht - Length - Time - Average speed - S/L speed Ratio
    Skandia - 98ft - 63.235hrs - 9.915 knots - 1.002
    Zana - 98ft - 63.475hrs - 9.878 knots - 0.998
    Grundig - 66ft - 68.20hrs - 9.194 knots - 1.132
    Skandia, the fastest and, over twice the length of Margaret
    Rintoul, did not equal Rintoul’s S/L ratio!!

    Are we really making any real progress??
    The boats are going faster in absolute terms but is this accompanied by real advances in efficiency?? :?:
     
  2. astevo
    Joined: Sep 2003
    Posts: 69
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Sydney

    astevo Junior Member

    aside from just stiring the pot maybe look at similar size boats. things like mumm 30's would have speed/length rates far above this.

    look at this the other way. is a old thing like 'condor' 'kialoa' or 'windward passage' even going to compete with a similar sized modern maxi? and these aer much more recent than the 1950's vintage margaret ringtoul 1975/6 for kialoa.

    its the other side to the same coin.
    and im thinking about that self leveling idea...
     
  3. SailDesign
    Joined: Jan 2003
    Posts: 1,964
    Likes: 94, Points: 58, Legacy Rep: 650
    Location: Jamestown, RI, USA

    SailDesign Old Phart! Stay upwind..

    Since Open60s are regularly going round the world in less than 100 days - the answer is Yes!
    Assume 27000 miles (probably an understate=ment in real distance travelled, but about the diameter of the earth), and 100 days for the passage. That's 27000 miles in 2400 hours, or 11.25 knots. Assuming LWL is 60' (again, an exaggeration), then sqrt(LWL) is 7.75, so the speed/length ratio is 11.25/7.75 = 1.452. Allowing for mph/knots conversion, that comes to 1.452/1.151 = 1.262 for a V/L.

    Definately better than 1.126, and singlehanded t boot.
    Of course, the boats do it in less than 100 days routinely now, and sail considerably further than the actual diameter of the planet, so this is all an underestimate.
    Round-the-buoys boats getting better? Who knows - it doesn't really matter if they are racing level :p

    Steve
     
  4. Wardi
    Joined: Nov 2003
    Posts: 161
    Likes: 1, Points: 0, Legacy Rep: 15
    Location: Sydney

    Wardi Senior Member

    Given the difference in age, style, design and construction, the improvement of the open 60 does not look so big does it! ;)

    How about doing the same comparison comparing speed to displacement/length ratio! :D

    It is very easy to make a new design faster, just make it lighter and put on more sail. That does not make it more efficient or a better design though!!

    I am rather disappoined to hear you have no interest to improve the real performance of boats vs D/L ratio. I guess you are happy then to just sail a Star or Finn. Why bother design anything better as they are good level racing one designs already! :p
     
  5. DaveB
    Joined: Dec 2003
    Posts: 129
    Likes: 1, Points: 0, Legacy Rep: 11
    Location: Canada

    DaveB Senior Member

    Wardi,

    I'm havin' a hard time following your point... you're asking if we've made any improvements independent of "style, design and construction" and keep referring to parameters... Those parameters are used to describe boats and relate them to natural laws... As far as natural laws go I don't think that we'll ever improve...

    As far as boats go I think we have improved a great deal... Whether it's due to the new tools that we have or the designers is another question...

    Cheers,

    Dave B
     
  6. SailDesign
    Joined: Jan 2003
    Posts: 1,964
    Likes: 94, Points: 58, Legacy Rep: 650
    Location: Jamestown, RI, USA

    SailDesign Old Phart! Stay upwind..

    Wardy,
    Yes, given the radically different D/l ratios and SA/D ratios in use today, it looks like we haven't come that far. But you're leaving out the singlehanded round the world aspect there. A fully crewed O60 will do very much better than a single-handed one can do over 2700 miles. :)
    Don't be disappointed that I don't want to improve things - I do. But look at what the OC did, put the Star back in because, regardless of speed, it provided interesting racing. Personally, I dislike racing, preferring to just go out and go fast without having to compare to anyone else. I just don't "get" the whole tactical BS. Prolly scared by a tactician when just a baby :)
    As far as improving performance per D/L, well, let's just say I want to improve performance, but I really couldn't care less about where the D/L falls. Would a 200 D/l boat be any more exciting at 25 knots than a 50 D/L boat? Would it be as safe and controllable (given a shi-ite-load more mass)
    Steve "thoughts for the morning - now my brain hurts"
     
  7. astevo
    Joined: Sep 2003
    Posts: 69
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Sydney

    astevo Junior Member

    wardy it seems you are looking at design improvments that do not involve any of the following.
    reduction in weight. or reduced disp/length ratio
    better construction.
    better or bigger rigs.
    etc
    to quote.
    "Given the difference in age, style, design and construction, the improvement of the open 60 does not look so big does it! "

    what factors do you consider to be 'design' improvements.
    given that you have already effectively said that disp/lengh, and improvements in sail area, weight, beam, handling etc,are not real design improvements.

    the only thing i have come up with which doesnt fail this criteria is reduction of drag.

    i take it what you are really getting at is efficiency.
    How fast a boat goes compared to another of exactly the same general parameters?
    if the parameters of this boat include things like d/l and the things i listed above, the only thing that can make such a boat go faster is reducing drag by other means.

    this sort of problem is what boat designers are trying to solve on a daily basis. the most intense protagonists of this are the development classes. but even here real improvements are coming from weight reduction and all the other stuff.

    basically i get the feeling that you see efficiency as stemming from hull drag alone. not from increaing righting moment, reducing weight, or doing any of the other stuff which we know make boats more efficient in a real sense.

    personally i see efficiency as relating speed to length and sail area. so really who could argue that the most efficient craft of any (in its ideal conditions) is a sailboard.
     
  8. Alvaro M
    Joined: Apr 2004
    Posts: 4
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Victoria BC

    Alvaro M New Member

    This might be very off, but to be relevant, shouldn't comparisons between the races' mean speeds be somehow standarnized by the average wind speed/direction during the two events?
    Alvaro
     
  9. Wardi
    Joined: Nov 2003
    Posts: 161
    Likes: 1, Points: 0, Legacy Rep: 15
    Location: Sydney

    Wardi Senior Member

    I though it was simple, but here is another attempt!

    The fundamental relation controlling the speed of a displacement boat is its Displacement/Length ratio.
    For boats of a given D/L ratio, a canoe will generally go faster than a punt because it is a better design.
    ie: it has less resistance at all speeds and angles of heel.

    Thus if we are really making "real" improvements in hull design, then current boats should perform better than those of 50 years ago, based on their D/L ratio.

    The article by Billy Hughes simply argues that little improvement has been made in fundamental design, even when based on Speed to Length ratio, let alone speed to D/L ratio.

    Modern design advances are mainly in the area of improved materials allowing lighter weight and more stability. They can carry more sail area, so the boats go faster in absolute terms. But so they should!! We all knew that from the beginning!....

    But are there any real improvements in the fundamental design when you compare them on the basis of their D/L ratio?.
     
  10. Jeff H
    Joined: May 2004
    Posts: 40
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Annapolis, Md

    Jeff H Junior Member

    I think that there have been huge improvements in design over the past 40 years, even given boats of the similar displacement to length ratios. Just compare a 40 foot CCA/RORC era boat to a 40 foot IOR era boat, to a 40 foot IMS era boat. Oddly enough they are not all that far apart in weight, but if we look at the differences, better engineering has allowed the IMS style boats to have lighter and stronger hulls, and as a result can carry greater ballast ratios carried further the from the center of buoyancy resulting in greater stability. This greater stability is what permits IMS derived designs to stand up to their larger sail plans.

    But beyond that, the finer entries, and more powerful stern sections, careful hull modelling and better sail shaping on the fly allow modern boats to have way less drag as they pretty much stay in trim as they heel (at least compared to IOR ear boats), develop less weather helm, and lose less speed with each wave (as compared to CCA/RORC or IOR era boats). The highly efficient keel and rudder foils further contribute a reduced drag so these boats can actually be sailed with less sail area for their displacement in heavy going, which in turn is easier on the crew.

    I get to sail on a wide range of boats from a lot of different eras throughout any given year, and it is not hard to percieve the massive improvements in speed and ease of handling in boats over the past 50 years.

    I suppose that you could prove that older boats have equal performance by setting up a some kind of fanciful non-dimensional ratio, but in any kind of realistic comparison, either by length, sail area, or displacement, modern boats are much faster at either end of the spectrum (light or heavy going)and certainly a lot easier to handle at speed or in heavier going.

    Respectfully,
    Jeff
     
  11. SuperPiper
    Joined: Jan 2003
    Posts: 362
    Likes: 5, Points: 18, Legacy Rep: 58
    Location: North Of Lake Ontario

    SuperPiper Men With Little Boats . .

    Wardy, you are trying to tell these guys that there ain't no Santa Claus. They just do not want to believe you.

    We know from this forum that most of the design work from the past 50 years has been spent on finding the corners of the various handicapping rules. If Herrschoff had had carbon fiber and canting keels, he would have built a VOR70. Modern boats are more stable, easier to crew, have large mainsails that are easier to reef, but, still only go as fast as Christopher Columbus.

    You won't read that in the brochure for a new boat.
     
  12. PAR
    Joined: Nov 2003
    Posts: 19,133
    Likes: 473, Points: 93, Legacy Rep: 3967
    Location: Eustis, FL

    PAR Yacht Designer/Builder

    By the rather limited scope of the discussion that Wardi has placed in this comparison, I'd have to agree to some of what he suggests. Good design is always good design, but you must compare apples to apples.

    Boats like LFH's big, seemly under canvassed ketch have a racing record to be envied by all, but is no match against a modern, similarly displaced vessel. They aren't even close in the numbers that mater. How can a boat that had a 30% ballast to displacement ratio compare with a 50% ratio'd craft? They could displace the same, but wouldn't have similar SA/D, drag coefficient, stability, acceleration potential, maneuverability and a host of other factors.

    A first class racing yacht of 50 years would have a full working interior, complete with raised panel bulkheads and curtains. It would likely have a full keel, though well cut back by the standards of the day, undivided appendages, cotton sails, built down sections, and a pretty low ballast to displacement ratio by today's norms. The same "displacement" craft used currently will have sails a fraction of the "in use" weight of the old duck, rigging hard points and hardware that shave many pounds of weight aloft, fast acting winches, pipe berths and plastic down below, divided appendages of far better design and efficiency, much decreased wetted surface in her sections. This doesn't even touch the "numbers" but does show the advances made.

    On the other hand, I'd much rather be at sea, racing or not in that big ketch of LFH. It's a much more comfortable, predictable and behaved yacht. I used to do a lot of deliveries and have had the pleasure of the helm on many fine sailing craft. None, without exception has compared with the joy of driving a "Bounty" or "big Ti" in whatever going there may have been up mother nature's butt that day. High ballast ratios make jerky boats, but quick in stays and can cling on to a wisp, but not a good time if you're on the fore deck and the skipper releases the helm while he swats a bee (time to practice the MOB drill)

    I use to love the races and still do, but to a much less extent. I get much more joy from a well balanced boat, where a big gust, a trip away from the helm or not paying attention isn't going to toss my stuff all over the cabin sole. I'm finding it hard to pay attention to the race from my hammock hung between the sticks, maybe they'll design a course that is a long broad reach, followed by another and another, with maybe a brisk close reach back to the dock at around say happy hour.
     
  13. SailDesign
    Joined: Jan 2003
    Posts: 1,964
    Likes: 94, Points: 58, Legacy Rep: 650
    Location: Jamestown, RI, USA

    SailDesign Old Phart! Stay upwind..

    Part of the problem is that physics is physics. I know, "duh!" But... for a given slenderness ratio, D/L ratio, etc, the "hull speed" is going to limit how fast a given boat is. If you want more speed, you simply go for a different point on the curve, or jump into a planing hull.
    Advances in materials and structure have definitely introduced a faster boat, but not if you impose Wardi's restrictions that it have the same base numbers. As JeffH says, improved ballast ratios have upped the speed capabilities, but in the heavy stuff, a displacement hull is a displacement hull is a displace.... you get the picture.
    THe only real improvement in recent times has been the ability to design boats that can plane/surf on a regular basis without the help of a large following sea. CAll it a "loophole in the laws of physics" if you will, but it IS faster :)

    Steve
     
  14. astevo
    Joined: Sep 2003
    Posts: 69
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Sydney

    astevo Junior Member

    i just got around to reading the entire article from billy hughes( imguessing not the ex-AUS. PM). once again it really is worth reading. infuriating reading at its best. the kind of stuff that makes you want to plough down the old salts in their slow heavy vintage shitboxes

    his description of racing talked about the benefit of being able to bake scones and roast dinners whilst managing to win an early syd to hobart. and how real yacht shouldnt need rail meat.

    the article makes reference to the length of scandia zana Xena etc. these boats are all much bigger that margaret ringtoul, but if we actually look at waterline lengths not LOA it pulls up the s/l ratio by maybee 5 to 10%. if we look at similar sized boats in to 30-40 ft loa range you get s/l ratios far and above that of margaret ringtoul.

    ask the question what would a mumm 30 do to margaret ringtoul. or a thompson 920 or even an old adams ten.

    we dont go racing to bake scones. we race to get from a to b as fast a possible. thats what it takes to win a race of any kind. how much comfort or the number of scones you eat on the way has no reflection on the race.
     

  15. SailDesign
    Joined: Jan 2003
    Posts: 1,964
    Likes: 94, Points: 58, Legacy Rep: 650
    Location: Jamestown, RI, USA

    SailDesign Old Phart! Stay upwind..

    You go racoing to get from A to B "faster than anyone else", THAT is what wins races :)
    Being able to cook scones while doing so, rather than sitting on the rail for hours getting soaked, must necessarily make for a more enjoyable time. PLEASE tell me you prefer eating scones and being warm to being hungry and cold...
    Steve
     
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.