[VSK4] Laser-Standard - 2nd version from Tom

Virtual Skipper 4 offer the possibility to import own boat 3D models.<br>
3D artists and players can now meet here to share models and advices.<br>
Virtual Skipper 4 offre la possibilité d'importer vos propres modèles 3D de bateaux.<br>
Les artistes 3D et les joueurs peuvent maintenant se réunir ici pour partager leurs modèles et conseils.

Kwasi
Matelot
Posts: 142
Joined: 10 Oct 2005, 09:32

Post by Kwasi »

yes, i know, that they are difficult to find, that is why we are asking here :)

Personal Mail sent!
GBR13697
Capitaine
Posts: 153
Joined: 28 Oct 2005, 10:20

Post by GBR13697 »

Here is some partial data (lifted from http://www.laserforum.org/showthread.php?t=184

Wind Speed Close Hauled Beam Reach Broad Reach Downwind
6 kts----------4 kts-----------5.4 kts--------5 kts---------- 4.1 kts
9 kts----------4.8 kts---------6.3 kts--------6.1 kts--------5.5 kts
12 kts---------5 kts-----------7.3 kts--------8 kts----------6.7 kts

Data did not go any higher up the wind range, and links to diagrams have died. However, in more than 12 knots a Laser will be planing on beam reach to downwind (not close hauled) so speeds are likely to double.
GBR13697
Kwasi
Matelot
Posts: 142
Joined: 10 Oct 2005, 09:32

Post by Kwasi »

ok, thnx for this 1st draft.

questions:

translated in TWAs it would be:

Close hauled: TWA 50

Beam reach: TWA 90

Broad reach: TWA 120

Downwind: TWA 170

is that correct?


other question:

how is close hauled speed developing in more wind against the waves?
maybe slower in f7 than in f5&f6?
Rs200
Capitaine
Posts: 239
Joined: 18 Nov 2005, 13:17
Location: Manchester, England
Contact:

Post by Rs200 »

Seems Ok, I'd change clos haules to 45 degrees. The tacking angle for a Laser is 90 degrees.

Downwind is more like 175-9 degrees.

peed upwind in a force 7 is less than force 5, yes, especially in waves.

Did you get my e-mail?
Harry
GBR13697
Capitaine
Posts: 153
Joined: 28 Oct 2005, 10:20

Post by GBR13697 »

I have worked out a polar diagram of sorts. Seems a bit nearer reality to me, but I am not a Laser sailor (Fireballer) so it may need some adjustment by the experts. But it is a start!

http://www.btinternet.com/~tammyowl/LaserPolar.jpg

GBR13697
Kwasi
Matelot
Posts: 142
Joined: 10 Oct 2005, 09:32

Post by Kwasi »

so, with TWA 50 the Laser would do 8.5 knots upwind....

I can hardly imagine.

What about the 30knots dw?
I mean, ok, there might have been a Laser that has done so, but we should always be talking about average speed in these conditions. Consider it at coastal waters, without too big wave interference.

The polar is looking logically, but to me it seems, that general speed is too high.


Btw: Thnx, Harry, got your mails. It seems to be good and handy help.
User avatar
andynz
Moderator
Posts: 1063
Joined: 10 Nov 2005, 02:25
Location: http://www.vys.co.nz
Contact:

Post by andynz »

Kwasi wrote:What about the 30knots dw?
Well I used to sail a laser but admit that was 25 years ago.... but I would have thought you probably could not exceed 15 knots downind. Certainly 30 knots would be impossible in F7 conditions.

Of course that has not stopped many other models being released with unrealistic performance :)
Kwasi
Matelot
Posts: 142
Joined: 10 Oct 2005, 09:32

Post by Kwasi »

andynz wrote:Of course that has not stopped many other models being released with unrealistic performance :)
That is mainly causee due to the fact, that the polars, you are telling vsk are not "translated" correctly.

Let's say, you set max upwind speed at 5 knots, it will be 7 or 8 ;-)
GBR13697
Capitaine
Posts: 153
Joined: 28 Oct 2005, 10:20

Post by GBR13697 »

My polar does not suggest anything like 30k - the scale only goes up to 21k! Plus, I thought these were theoretical maximums that would only be reached in VSK4 if the boat was being sailed at perfect efficiency.
I agree that speeds may be a bit high (not that unusual in some VSK custom models) - I may have been too believing of Laser sailors' claims!
However, in a Fireball, I have averaged 18k for 3.5 miles over a timed run in a Force 5. This was an average, so I must have been going faster at times. I also know I have gone a lot faster in more wind - although not in total control! I would estimate the Fireball maximum at over 25k, so a theoretical maximum approaching 20k in a Force 7 in a Laser does not seem too unreasonable. There will not be many Laser sailors capable of sailing in a Force 7 anyway.
The main object was to get a polar diagram more characteristic of a Lasers angle for best VMG downwind, and to reproduce the jump in speed when it starts to plane. I am just trying to assist in improving the thing so that virtual sailors will be keen to sail it.
GBR13697
User avatar
CANKnot
Moderator
Posts: 1320
Joined: 09 Nov 2005, 22:21

Post by CANKnot »

One thing, in 30knts of wind the "average" laser sailor will spend approxiamately 50% of the time with the mast in the water and the dagger board in the air... ;)
In theory there is no difference between theory and practice, but in practice there is.
Kwasi
Matelot
Posts: 142
Joined: 10 Oct 2005, 09:32

Post by Kwasi »

GBR13697 wrote:My polar does not suggest anything like 30k - the scale only goes up to 21k! Plus, I thought these were theoretical maximums that would only be reached in VSK4 if the boat was being sailed at perfect efficiency.
I agree that speeds may be a bit high (not that unusual in some VSK custom models) - I may have been too believing of Laser sailors' claims!
However, in a Fireball, I have averaged 18k for 3.5 miles over a timed run in a Force 5. This was an average, so I must have been going faster at times. I also know I have gone a lot faster in more wind - although not in total control! I would estimate the Fireball maximum at over 25k, so a theoretical maximum approaching 20k in a Force 7 in a Laser does not seem too unreasonable. There will not be many Laser sailors capable of sailing in a Force 7 anyway.
The main object was to get a polar diagram more characteristic of a Lasers angle for best VMG downwind, and to reproduce the jump in speed when it starts to plane. I am just trying to assist in improving the thing so that virtual sailors will be keen to sail it.
GBR13697
Ok, sorry for misreading the polar.
We will now use your polar as long if that is fine with the comunity!

If you have proposals or improvements for this polar
http://www.btinternet.com/~tammyowl/LaserPolar.jpg
let us know!
Kwasi
Matelot
Posts: 142
Joined: 10 Oct 2005, 09:32

Post by Kwasi »

There we go:

Image

You can find the download at www.vivarace.de

http://www.vivarace.de/downloads/index.php?cat=99

Thnx to Tom :D :D :D :D :D :D :D :D
and especially thnx to the australian comunity who are helping a lot with good critics. The boat still is far away from being perfect, but it is surfing a lot more, it looks better and the angles are closer to reality.
If there is more critics, don't hesitate, let us know.

P.S.: The install-exe is in english language now.

P.P.S: If you want to share Toms Models on your Internet Site, feel free to do so. Just leave a short message, where you are placing Download Links, so we don't lose overview :-)
GBR13697
Capitaine
Posts: 153
Joined: 28 Oct 2005, 10:20

Post by GBR13697 »

Thanks Tom & Kwasi. I will look forward to trying it out.
GBR13697
GBR13697
Capitaine
Posts: 153
Joined: 28 Oct 2005, 10:20

Post by GBR13697 »

I have only had a brief chance to try it out. It is definitely getting there!
1) The more upright mode makes it look a lot more like a dinghy, and thereby much more realistic.
2) As Kwasi says, surfing is a lot better
3) General upwind and running speeds seem fairly accurate
4) The dead downwind VMG and boatspeed seems more realistic
5) Reaching (TWA 75-135) speeds seem rather low from top end of F4-F5 (where I would expect a Laser to start planing and accelerate quite markedly) and broad reaching (TWA 90-150) in F6-F7 where it should be planing wildly (if not totally out of control!).

I appreciate that point 5) i.e. the transitional jump and acceleration from non-planing to planing is difficult to reproduce, and I have no idea how it is achieved in VSK boat modelling terms. However, this will be the key to realistic dinghies in VSK (along with the advances already made with the Laser) and could lead to some great new boats in VSK.

I would be interested to see what the real Laser sailors have to say. A few more tweaks with reaching would be gratefully received. Keep up the good work, and thank you!
GBR13697
Kwasi
Matelot
Posts: 142
Joined: 10 Oct 2005, 09:32

Post by Kwasi »

Wooohh

That sounds good :)

Well, as said, we are happy to get a feedback, so try to describe the things as accurate as possible. We will get back into that.
Locked