Not Just Another Pretty Face

Originally posted to SLSailing.com on Jan 27 2008

 

When Verkin Ravin’s Tetra 35 v1.0 was released, I was one of the first standing in line to buy it. If you’ve followed Verkin’s efforts in SL, you know he’s a wonderful artisan; his boats are full of highly realistic and often humorous details. My Tetra v1.0 looked just like the real-life 35ft cruisers I’ve sailed, and it is one of the prettiest boats I own.

Tetra

However… I admit I’ve never sailed my Tetra35 v1.0 much; I thought it was just too slow. When I complained to Verkin about my Tetra’s tardiness, he gave me a long, appraising look and said “Jane? You should switch to decaf…”

That may be true, but it’s somewhat off-point. The v1.0 boat reminded me of it’s namesake, the pretty Tetra fish people put in their home aquarium. Nice to look at, but not enough ‘attitude’ for the racecourse.

Well, that shows you how much Jane knows about Tetras… in the tank or in SL. I recently found out there’s another RL Tetra, Hydrolycus scomberoides; it’s known as the “Sabretooth” or “Vampire” Tetra. That fish comes with six-inch fangs and a borderline personality disorder. It actually eats piranhas for lunch.

Guess what? There’s now a new Verkin Raven Tetra35 upgrade that has just that much attitude.

I first tripped over the The Tetra v1.2 when it was in beta, and Taku Raymaker started logging hotlaps scores that blew away other boats. The picture above shows Taku checking the luff on his T35 main.

I got my hands on a T35 v1.2, and Taku was right! According to the current  Handicap Hotlaps race data, the v1.2 is a full ten percent faster than the benchmark Trudeau Defender/ Trucordia Yawl. Verkin’s developed a special ‘Racing Lite’ version of the Tetra as well, so sailors can switch to a reduced-prim load version of the boat for competition racing. The Lite version is a great compromise for a boat that wants to maintain a distinctive high level of detail but then suddenly turn lean and mean on the raceline.

If you pull up the floorboards on the Tetra35, you’ll still find Tako physics, but I’m not complaining. The boat is beautiful, and the Tako genes make it very easy for anyone to sail from day one, Tako gestures and all.

No surprise, I’m not the only person who’s had an eye out for a racing Tetra. Within two or three days of the T35 v1.2 release, skippers were organizing pick-up races with a half-dozen or more boats converging on the start line, eager to put this boat through it’s paces.

Taking up that challenge, Race Director Hpathe Boucher’s caught the Tetra 35 race fever. Beginning January 28 he’s starting a regular Monday race series at 4:00pm. Want to race your new Tetra? Want to crew and see what the boat’s like? Join Hpathe on Mondays in Bismarck Sea. That Tetra… it’s not just a pretty face anymore!

Blow (a reprise article from 2008)

by Vin Mariani

[Note: This article was originally posted January 25, 2008
by Vin Mariani on SLSailing.com. Although it is five years old,
the information in the article (and in the subsequent “Part II“)
still applies to many SL boats that have wind algorithms
based on Kanker Greenacre’s original Tako scripts. /JFos]

Several weeks ago a group of us were sitting around the table on the terrace of Nantucket Yacht Club, knocking back a few and talking about the wind. Jane Fossett asked, “do all boats in a given race feel the same variation of wind at the same time?” A simple question, yet a critical one, as the answer tells us whether winning races is a matter of randomness or of skill. We all want to believe it is skill, don’t we? But if I experience a different wind variation in a race from my competitors, I can always say, “you won because you happened to get better wind than me, this time.” But if we all experienced identical wind fluctuations during the race, then I must admit, “you made more skillful use of that wind than I did.” So Jane’s question is central to the meaning of sailboat racing in SL.  We had better hope that all racers experience the same wind variations, or winning a race would be pretty much just a roll of the dice.

We already know that wind variations affect hot lap times. The variation adds a random factor that can only be overcome by persistent repetition, or by setting the wind variations to zero. But, is the order of race results also affected by wind variation? The more we talked about the subject, the more questions we uncovered. Turns out, we don’t really know much about the wind at all. So I decided to study the subject intensively and see how much I could learn. This article presents the results of an investigation into how race wind works in detail. It’s surprising how much we CAN know about the wind. I’ll present the answers to all of the following questions. If you think you understand the wind already, you can consider this a quiz.

Questions:

1. Once a boat gets its wind parameters from a windsetter, how does it still know the “current wind” when it is far, far away from the windsetter?
2. Jane’s question: in a race, do all boats of a type feel the exact same wind variation at the same time? (Are they lifted and headed together?)
3. Even if they are in different sims?
4. Do different types of sailboats in the same race feel the very same wind variation as each other? Or does the wind depend on the type of boat?
5. Does the wind vary from place to place at a given time, the way that it does in RL?
6. Does the wind change when you cross a sim boundary?
7. Does the wind have any day/night variation, the way it does in RL?
8. Wind speed and direction are seen to occasionally deviate by more than the +- parameter values; how much does it really vary?
9. Can we know the entire wind variation in advance?
10. Would knowing it affect racing or hot laps?

Answers:

1. Each boat that can use race wind carries two internal functions inside its scripts that can tell that boat the exact wind speed and direction whenever the boat “asks”.  These two functions trace back in time at least to Kanker Greenacre’s Tako version 2.1 scripts, (which can be found on the LSL Wiki, a repository for scripting knowledge). Here is Kanker’s original code fragment:

In case you find the scripting opaque, here are the functions themselves, pretty-printed for clarity: 

The specific outputs of these two functions depend on the five wind parameters, which are shown in red. Once those five parameters have been received by the boat, that boat’s wind functions will then proceed to vary only as a function of SL time, wherever the boat goes. At the default rate of 1.0, the variation repeats itself every 24 minutes, all day long. Below are plots of the variations over one cycle, using the particular wind parameters of the NYC race line (spd = 11, dir = 5, spd+- = 3, dir+- = 15, rate = 1.0). The basic curve shapes would always be the same at other race locations, although the axes scales would depend on the five parameters of the local windsetter.

Although these two plots “tell the whole story” I find it hard to relate speed and direction to one another. What I would like to see is both speed and direction on the same plot. Rather than try a 3-dimensional plot, which can be very hard to visualize, I made a polar plot of just direction and strength, where time is only implied. In the plot below, the instantaneous wind wanders slowly along the curve over time, leaving a blue dot every 15 seconds. The average wind of 11 m/s coming from 5° is marked as a big green dot in the center. Note that in SL, 0° is due East, not due North, as we might expect.

Here we can see that the wind wiggles around the average with many small deviations, and it has a few rare larger deviations, like real wind does. And the variations are complicated enough that you probably would never notice a pattern.  But shown like this, my mind sees a butterfly in the red Rorschach blot. Nice work, Kanker.

This is a good place to stop for a rest. We still have nine more questions to answer and, although the answers will be brief, this article is plenty long already.

To be continued. Questions are welcomed, but first check to see if I’ve already promised to answer that question in Part 2.  If your brain is full, go sailing.

Vin

Sizing Up the Zone

This Article was origially posted on SLSailing.com on January 15th, 2008. 

 Hi! You don’t need to read this article!

Not that you ever thought you needed to read anything else I ever wrote, but the only thing I’m going to say today is something really silly. Nonetheless, I think this bears repeating:

Big Boats need more room to turn than Little Boats.
Got that? Good!
Since I get paid by the inch here (joke), let me give you some details:

Do you remember last week? Neither do I. However, re-reading COM it looks like I wrote about a few races where ”turns at the marker buoys“ seemed to be important.  No surprise, this week showed many other races where those marker turns proved critical for the winning skipper. I could tell you about those races, but I won’t… at least not today. Instead, I want to talk about the size of your error-genous zone.

I’m sure you have all seen it.  Surrounding many of the race buoys in USS and the ACA sims you will find a faint, broken white circle. That’s the Two Boatlength  Zone where its easy to make errors since special rules apply:

 You need a Zone because things often get tense when more than one race skipper approachs a marker at the same time. Extra rules kick in, particularly Rule 18. Here’s part of IASF Rule 18 as it applies to Real-Life sailboat racing:

18 ROUNDING AND PASSING MARKS AND OBSTRUCTIONS

In rule 18, room is room for an inside boat to round or pass between an outside boat and a mark or obstruction, including room to tack or gybe when either is a normal part of the manoeuvre. …

18.2 Giving Room; Keeping Clear

(a) OVERLAPPED – BASIC RULE

When boats are overlapped the outside boat shall give the inside boat room to round or pass the mark or obstruction, and if the inside boat has right of way the outside boat shall also keep clear. Other parts of rule 18 contain exceptions to this rule.

(b) OVERLAPPED AT THE ZONE

If boats were overlapped before either of them reached the twolength zone and the overlap is broken after one of them has reached it, the boat that was on the outside shall continue to give the other boat room. If the outside boat becomes clear astern or overlapped inside the other boat, she is not entitled to room and shall keep clear.

(c) NOT OVERLAPPED AT THE ZONE

If a boat was clear ahead at the time she reached the two-length zone, the boat clear astern shall thereafter keep clear. If the boat clear astern becomes overlapped outside the other boat, she shall also give the inside boat room. If the boat clear astern becomes overlapped inside the other boat, she is not entitled to room. If the boat that was clear ahead passes head to wind, rule 18.2(c) no longer applies and remains inapplicable.

 

Confused? Me too. It basically says that if two overlapped boats enter the zone, the inside boat has ROW. It’s a common problem, as demonstrated by the fourth race in this past Sunday’s Big-Boat series:

As you can see, Gemma Vuckovic and Vin Mariani are overlapped, and Gemma has the inside track within the “zone.” Vin was subsequently disqualified when he fouled Gemma’s boat taking the turn. This was a particularly interesting case, however, since Vin’s boat was technically outside the Zone for much, if not all, of the Marker turn.

Don’t worry. I’m not to go into a long, tedious discussion of the nuances of Sailing Rules here (cough, good grief).  Let me just say I usually reduce SL Racing’s Rule 18 to two simple ideas:

#1: If you are heading for the mark and enter the Zone overlapped with another boat, the INSIDE boat has Right Of Way (ROW), and

#2: If you are heading for the mark and another, non-overlapped boat is trying to do the same thing, the boat on STARBOARD TACK has ROW.

I’m only bringing this whole business up to make one simple, new point: The Two Boatlength Circle we standardly use to decide this stuff is designed for Tako races; it does not apply for other boat classes. Take a look at the picture below:

A Tako is shorter than a Larinda (Mirabile dictu)! It prolly violates Newtonian physics to fit two or more Larindas within that two-boatlength circle we currently use. If you look at the image below, two Larinda boatlengths is pretty much the full distance from the Bismarck Sea red Race Buoy to the NYC Clubhouse!

I’d therefore like to argue for a small change that will hopefully prove easy to swallow. For future SL Sailboat races where Rule 18 is enforced, the white circles should only be used for Tako, Fizz and Beach Cat competitions. For Trudeau, ACA32, and ACC races, the ‘zone’ is much larger and should be left to the discretion of the Race Director.

I know that’s a tiny, obscure point… but it wasn’t so bad, was it?

_______________

Sizing Up the Zone

 

January 15th, 2008 · 

 

 Hi! You don’t need to read this article!

Not that you ever thought you needed to read anything else I ever wrote, but the only thing I’m going to say today is something really silly. Nonetheless, I think this bears repeating:

Big Boats need more room to turn than Little Boats.

Since I get paid by the inch here (joke), let me give you some details:

Do you remember last week? Neither do I. However, re-reading COM it looks like I wrote about a few races where ”turns at the marker buoys“ seemed to be important.  No surprise, this week showed many other races where those marker turns proved critical for the winning skipper. I could tell you about those races, but I won’t… at least not today. Instead, I want to talk about the size of your error-genous zone.

I’m sure you have all seen it.  Surrounding many of the race buoys in USS and the ACA sims you will find a faint, broken white circle. That’s the Two Boatlength  Zone where its easy to make errors since special rules apply:

 You need a Zone because things often get tense when more than one race skipper approachs a marker at the same time. Extra rules kick in, particularly Rule 18. Here’s part of IASF Rule 18 as it applies to Real-Life sailboat racing:

18 ROUNDING AND PASSING MARKS AND OBSTRUCTIONS

In rule 18, room is room for an inside boat to round or pass between an outside boat and a mark or obstruction, including room to tack or gybe when either is a normal part of the manoeuvre. …

18.2 Giving Room; Keeping Clear

(a) OVERLAPPED – BASIC RULE

 When boats are overlapped the outside boat shall give the inside boat room to round or pass the mark or obstruction, and if the inside boat has right of way the outside boat shall also keep clear. Other parts of rule 18 contain exceptions to this rule.clear astern becomes overlapped outside the other boat, she shall also give the inside boat room. If the boat clear astern becomes overlapped inside the other boat, she is not entitled to room. If the boat that was clear ahead passes head to wind, rule 18.2(c) no longer applies and remains inapplicable.Confused? Me too. It basically says that if two overlapped boats enter the zone, the inside boat has ROW. It’s a common problem, as demonstrated by the fourth race in this past Sunday’s Big-Boat series:

(b) OVERLAPPED AT THE ZONE 

If boats were overlapped before either of them reached the twolength zone and the overlap is broken after one of them has reached it, the boat that was on the outside shall continue to give the other boat room. If the outside boat becomes clear astern or overlapped inside the other boat, she is not entitled to room and shall keep clear.

(c) NOT OVERLAPPED AT THE ZONE
If a boat was clear ahead at the time she reached the two-length zone, the boat clear astern shall thereafter keep clear. If the boat

 

As you can see, Gemma Vuckovic and Vin Mariani are overlapped, and Gemma has the inside track within the “zone.” Vin was subsequently disqualified when he fouled Gemma’s boat taking the turn. This was a particularly interesting case, however, since Vin’s boat was technically outside the Zone for much, if not all, of the Marker turn.

Don’t worry. I’m not to go into a long, tedious discussion of the nuances of Sailing Rules here (cough, good grief).  Let me just say I usually reduce SL Racing’s Rule 18 to two simple ideas:

#1: If you are heading for the mark and enter the Zone overlapped with another boat, the INSIDE boat has Right Of Way (ROW), and

#2: If you are heading for the mark and another, non-overlapped boat is trying to do the same thing, the boat on STARBOARD TACK has ROW.

 I’m only bringing this whole business up to make one simple, new point: The Two Boatlength Circle we standardly use to decide this stuff is designed for Tako races; it does not apply for other boat classes. Take a look at the picture below:

A Tako is shorter than a Larinda (Mirabile dictu)! It prolly violates Newtonian physics to fit two or more Larindas within that two-boatlength circle we currently use. If you look at the image below, two Larinda boatlengths is pretty much the full distance from the Bismarck Sea red Race Buoy to the NYC Clubhouse!

I’d therefore like to argue for a small change that will hopefully prove easy to swallow. For future SL Sailboat races where Rule 18 is enforced, the white circles should only be used for Tako, Fizz and Beach Cat competitions. For Trudeau, ACA32, and ACC races, the ‘zone’ is much larger and should be left to the discretion of the Race Director.

I know that’s a tiny, obscure point… but it wasn’t so bad, was it?

_______________

Got that? Good!

Manul takes a Winning Turn (Reprise)

(This article originally posted at Slsailing.com on January 10, 2008)

This week’s ACA32 races were pretty exciting. Yuukie Onmura, Liv Leigh, Manul Rotaru, and joepie Korobase all competed. The skippers were fairly evenly matched and traded wins back and forth while racing the familiar NYC B-1A Course around Vella Lavella Island. Here’s the course map, in case somehow you’ve forgotten:

Let me tell you a bit about the second race, since it had a few nice twists and turns that made me wonder if “Manul Rotaru” was a really bad Latin translation for ”dextrous turning.”

As shown above, the race got off to an interesting start with Yuukie Onmura and Liv Leigh overlapped and parallel on starboard as they approached the Start. Liv jumped the gun a bit, however, crossing the line early. Although she immediately spun her boat around to get a valid start, the misstep cost Liv nearly half a minute.

Yuukie’s start was perfect, but also pretty risky; she hit the line at exactly 00:00! Manul Rotaru on the other hand seemed in little hurry, casually strolling onto the course at 00:11.

Once Manul woke up, however, he made up for lost time by skillfully beating to Windward across Bougainville Strait. As shown above, Manul had nearly caught up with Yuukie as they were about to enter New Georgia Sound. The picture also shows that Liv’s making the best of a bad situation; she crossed the line on a port tack, but is far behind the lead boats.

Going for the first mark, the race turned into a duel between Yuukie and Manul that continued over the remainder of the course. As you can see in the above picture, Manul is close-hauled on port as he descends on the red buoy, while Yuukie is really ‘pinching’ as she tries to reach the mark on a starboard tack.

Even though Manul is on port tack, he is better positioned here as he reaches the turn, since he can fall off the wind and gain ground as he cuts close to the mark. Yuukie can’t get closer to the red buoy without tacking, so she’s forced to go wide at the turn.

The picture above illustrates this point. Yuukie is nearly head-to-wind and has begun her tack, but she’s nearly 2 boatlengths high of where she’d like to be.

Manul meanwhile has finished his turn and is starting a fast beam reach going South.

The image on the left shows the damage done by these maneuvers as Yuukie finishes her turn at the mark. Manul has picked up a substantial, several boat-length advantage and his lead will undoubtedly increase as he builds up steam on the long reach leg.

At this point, Yuukie is still resetting sails.

The image below shows the three boats in the “Roaring 40’s,” the three sim downwind run south of Vella Lavella Island. As predicted, Manul Maintained and broadened his lead as he entered Coral Sea For the return trip home.

But don’t count Yuukie out! She made a decisive hockey-stop turn at the Coral Sea Mark and expertly trimmed sail on the beam reach going North to fall into the leeward postion shown below, parallel and overlapped with Manul’s stern. GREAT sailing, Yuukie!

Yuukie now forced Manul to go to work again if he really wanted First Place. Manul rose to the occasion, and once again a Marker turn made the difference.

As shown below, both boats approached the final red buoy in front of NYC on overlapped starboard tack. However, Manul holds the inside position closer to the mark, effectively blocking Yuukie as he goes into this last sharp turn. Yuukie is still a boatlength or two leeward, and in that position she needs more headway before tacking to clear the mark.

The view below shows Manul cutting the turn with precision. Yuukie however has the tougher job here, but she calls the tack perfectly and actually gains ground as she brings her boat around.

The image below shows Yuukie’s bow aligned with Manul’s stern as they complete the tack and aim at the Finish Line. However, any boat will lose power tacking; Yuukie was able to close the gap partly because Manul’s boat slowed coming around the mark. This fact now works against Yuukie, since at the moment of the above picture Yuukie is the one losing speed while Manul’s boat begins to accelerate on the last short sprint to the Line.

Sure enough, Manul got that extra push and pulled slightly ahead again, barreling over the Finish for the victory a scant five seconds ahead of Yuukie. GREAT RACE!

Although I only had time and space to tell you about the above match, Tuesday’s ACA32 Race Fleet went on to complete three more races on the NYC B1A course. Yukkie captured two First Places, and Liv Leigh took the third! The ACA32 skippers are seasoned, skilled, and evenly matched. That’s a recipe for some pretty exciting races to come.