Connecting the Dots – Julian Bethwaite
Originally published on Sailing Anarchy website 13 August 2015.
For the umpteenth time I was asked 2 weeks ago what boats should a 12 year old Opie kid sail to best place him in a 49er when he gets into his late teens, early 20’s.
This mum was very smart, far greater grasp of numbers than I, spreadsheets, etc, but I still struggled to get the flow across, so I generated the following graphical representation, and she has come back and said, and I quote “Thanks for following up. Interesting graphical depiction of the relative properties of these classes of boats, brings the stats to life.”
So, what I am seeking from you guys/gals is a peer review!
I could give you all my figures, but I think that would predispose a bias, which I have little doubt I will be accused of. Instead, I plan to explain my rationale, and asked others to have a go at their own interpretation and maybe we can blend them and end up with something meaningful.
So what I have done is go to the RYA site and dig out the relevant PY [Portsmouth Yardstick] numbers.
http://www.rya.org.u… PN List v6.pdf
I have picked the boats mostly on simplicity, firstly if I did not know them, then I could not represent them.
I then went into the ISAF site and looked up the technical data
So I have exclusively used that information unless the RYA/ISAF data was simply wrong in which case I went into that class’s rules and gleaned it from there.
An example, 470 appears not to have a PY number, so I worked out approx. where it should be.
I included the IC because it’s too interesting not to.
And we all know a moth sails heeled to windward and greatly increases its RM by doing so, where as a Laser, when sailed “flat” is actually heeled about 6° to leeward.
I have not imputed these shifts in CoB, I have assumed the boats are all bolt upright as per their numbers.
Finally, I have used the ISAF HP definition about sailing faster than the wind, downwind, most of the time, to draw the red line.
Not sure why a 470 does not do it more often (tack downwind), but we also know a 29er does, most of the time (and yes, I know why a 29er does).
What is irrefutable is that a 5o5 and to a lesser extent a I14, spend a lot of money and effort setting their boats up so they can quite deliberately switch to HP modes both up-wind and down wind, so, from my POV I consider the 5o5, the tipping point boat, it has a foot in both camps, one could say the best of both worlds.
So the lobes etc on the graph.
PY is pretty easy, bottom of the solid is the PY number.
Displacement to the left of the graph is based on Power to Weight ratio.
Then the Circle compared to the Oval, has to do with RM/SailArea.
So a Moth is round because it has the same SailArea upwind as down, so my thinking is that a sailors ability to create a difference is equally possibly up-wind as it is downwind, where as a 49er the performance opportunities are greater down-wind because of the spinnaker.
The ovals are vertical because boats go a lot faster down-wind than they do up-wind.
That’s enough from me, be really keen on some other ideas on this.
Love to hear your comments, and be rest assured I won’t be offended!
In response to some of the questions and feedback on Sailing Anarchy, Julian made the following comments:
14 August 2015
Did not include a F11 because it does not have a PY. But I thought I had to include a 470 because it’s an Olympic class though I did not include a RSX because I was sure that I would get it too far out and it’s not a pathway to the original question which is a 49er/FX.
Can flip the graph, that’s easy.
To get the ovals or the dia of the circles I put the sail area over the RM.
So the width of the oval or the dia of the circle is the working sail area of RM
The height of the oval is the working sail area plus the spinnaker so total sail area of the RM.
I orientated the ovals vertically because as you go upwards you get more performance and most boats go faster under spinnaker than not.
16 August 2015
Stanno, re the F11, its very much an Australian boat, that has pluses and minuses. And it has no PY number, (this whole document is heavily English skewed.) I have never sailed a F11, I certainly have worked on them and admired them from afar, great kids boat, in the same vein as what is being proposed here they would be better than a RS Feva but its biggest drawback is no international competition. Kids need to be “blooded” in an international event before they are 17, 20 at the outside. That event can be in your case, Australia, but you need an international class with 100+ boats.
JimC, thanks for the 973PY for a 470, I will move it, it will virtually overlap a Fireball, and, OK, once you move it back down the graph, then why they don’t tack downwind becomes obvious. Nicky and I in Cherubs, remember spending a lot of time on the wire downwind and these had much smaller spinnakers than they do today, so I can only assume we were running apparents.
Doug, I will flip the graph for you, but your colour concept I’m not sure is relevant.
Steve, my intuitive take is as you go up the graph, you go faster, down you go slower, in its present form, as you go left, you’re increasing power, as you go right you’re decreasing power, just trying to KISS and give the umpteenth+1 mum something I can explain over the time it takes to drink a cup of coffee without getting into semantics.
FY, every 29er skipper gunwale swings, yet they have no issue whatsoever going double trapeze-ing on a 49er every chance they get.
My take, and I know I’m getting subjective here which I really want to avoid is that trapeze-ing is functional, it can be learnt by just about anyone and with practice you get good at it. Apparent Wind Sailing [AWS] is subliminal, it has to become intuitive. Bit like learning a 2nd language, got to do it before your 17-18 or it becomes a whole different learning problem.
Re fast boats, there is very much a place for going out sailing in a slow boat in a big fleet, Laser for instance, and learning the discipline of grinding out those places and being very tactical. Sailing a single hander is great because you can’t blame anyone else when you muck up.
But nothing beats learning to work as a team. And learning in a fast boat just exaggerates that process because get it wrong you get wet.
Rasspuit, when you find it let me know!
Simon, I don’t want to go rocking axis’s because that implies bias, but you certainly have me thinking that WRT P/W ratio! We can work off a mean PW rather than an absolute and that will put roughly 1/2 the boats on one side and the other half on the other. We then can compress the vertical scale to get it to nicely fill an A4 page.
And by doing that you’re not being subjective, you will also get your 2 quadrants.
And you then can evoke the ISAF paradigm, WRT HP and draw a horizontal line there.
Worth a try, I will have to get my son to send me the file, see if I can do this in the next 24 hrs and we can re-convene!
16 August 2015
Also I point out this is unashamedly targeted at 49er, these kids and these parents what their kids to go down this path.
I’m sure there are an equal number of kids and parents that want to go down a Corinthian path also.
But that’s not what I am being asked, and it’s not my problem, maybe the sport’s but not mine.
Anyway, I have had another go based on Simon’s suggestions, but I have not flipped the graph, its simply too hard on a laptop.
All I have done is re-configure the horizontal scale so compressed the PY’s and then finding a mean because a bit arbitrary based on areas of the ovals/circles so it was very close to running through the 5o5, so I just used it, once again as the mean boat.
Let me know your thoughts.
17 August 2015
Some of you are missing the point of this, that was, a mum, for the umpteenth time asked me what steps where needed to get her little Johnny from Opie to 49er in such a way that he had a chance.
There are possibly 1000’s of track with 1000’s of outcomes, yes the 13ft skiff is a great boat, very Australian, but its directly up against the Cherub and it’s not gaining traction and if you put a 17 year old that has had one or 2 international events in say a 29er in a close to 200 boat fleet and his/her counterpart who has come out of the Manly 16ftskiff program in 13ft skiffs, in a 49er in Hyeres then blind Freddy knows what that answer will be.
And which IC PY number’s relevancy, its 25 places, seriously important to a IC sailor but to a parent wanting to know which way to go, I think not! For a US kid, I think that a stint in IC’s would do no end of good in learning AWS, just like a stint for a Manly (Sydney) sailor a 13ft skiff is good cheap path, but to cut it in the world of int 49er sailing you’re only putting off the inevitable and setting yourself up for tears.
I’m getting subjective now, and that’s defeating the point. I will stop.
The comments on price are also very interesting, and I do remember way back 2001 maybe there was a ISAF report on the cost of sails. It was done suitably at arms length, taking internet based prices and displaying them in terms of sq-m. Its possibly worth digging that out and up-dating it.
Hulls are a bit more difficult as most serious campaigns have 3 boats for logistic reasons. Even your keen 29er sailor leaves a boat in the UK for 2 years these days just to beat logistics and charter fees and then has another back home and cycles them, again approximately every 2 years.
That’s possibly a useful contribution. Let me come back to you with that. But it will be a few weeks, that will require some information.