JulianB
Super Anarchist
For the umptenth 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 rational, and asked others to have a go at there own interpretation and maybe we can blend them and end up with something meaning full.
So what I have done is go to the RYA site and dig out the relevant PY [Porthsmouth Yardstick] numbers.
http://www.rya.org.uk/SiteCollectionDocuments/technical/Web%20Documents/PY%20Documentation/2015%20PN%20List%20v6.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
http://www.sailing.org/classesandequipment/index.php
So I have exclusively used that information unless the RYA/ ISAF data was simply wrong in which case I went into that classes 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 its to 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 assume 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 dose not do it more often (Tack down wind), but we also know a 29er dose, most of the time, (and yes, I know why a 29er dose).
What is irrefutable is that a 5o5 and to a lesser extent a I14, spend a lot of money and effort setting there 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 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 wont be offended!
Jb
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 rational, and asked others to have a go at there own interpretation and maybe we can blend them and end up with something meaning full.
So what I have done is go to the RYA site and dig out the relevant PY [Porthsmouth Yardstick] numbers.
http://www.rya.org.uk/SiteCollectionDocuments/technical/Web%20Documents/PY%20Documentation/2015%20PN%20List%20v6.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
http://www.sailing.org/classesandequipment/index.php
So I have exclusively used that information unless the RYA/ ISAF data was simply wrong in which case I went into that classes 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 its to 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 assume 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 dose not do it more often (Tack down wind), but we also know a 29er dose, most of the time, (and yes, I know why a 29er dose).
What is irrefutable is that a 5o5 and to a lesser extent a I14, spend a lot of money and effort setting there 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 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 wont be offended!
Jb
