Category Archives: Columbia

Beating to Windward

Columbia and Patchogue are the two newest boats in the Trudeau line, and they continue the long tradition of style and performance that are a consistent trademark of Trudeau Yachts. There are lots of features about these boats to talk about, but today I wanted to focus on the reefing effects, and how they impact upwind performance of the boats.

Wind Engine. 

Before I can talk about reefing, I need to back up a bit and quickly remind people about the differences in wind engines in SL boats.

In real life, all sailboats see the same wind and are bound by the same basic laws of physics. That’s not necessarily true in Second Life however, where different vehicle wind scripts result in major performance differences. I discussed this a few months ago, noting that many popular boats in SL are powered by “true wind,” others by “apparent wind,” and still more by “something in-between.” Here’s a link to Mothgirl Dibou’s insightful discussion of this issue.

All Trudeau yachts over the past 18 months are based on an apparent wind engine initially introduced with the Trudeau Twenty. That basic design has been re-tuned and refined to match the specific characteristics of each new Trudeau vessel, and the underlying  Trudeau force algorithm is based on the same apparent wind equations skippers use in real-life.  Mastering these boats may prove a more realistic (and occasionally more frustrating) challenge to sailors, since the apparent wind speed (AWS) and the apparent wind angle (AWA) are constantly changing as the boat moves through the water. A skipper needs to ‘stay awake’ (just like Real Life!).

The chart below plots the “Speed Over Ground” (SOG) for six current Trudeau boats using optimal settings at a slow wind speed of 5.0 m/s. That slow wind speed makes it possible to get pretty accurate numbers for the different points of sail. It also gives a “baseline” performance estimate under conditions that don’t require reefing and cause relatively little heel.

With a 5.0 m/s breeze, Columbia (in Blue above) looks extremely similar to the J-Class (in Red). The boats come out of irons and start gaining momentum at around 38-40° AWA and achieve a  maximum upwind velocity at approximately 50° AWA.   Both boats (in fact all Trudeau boats) then exhibit a near-linear decay in performance response as the point-of-sail moves progressively downwind. (Columbia’s spinnaker effect is shown here. )

Patchogue’s wind response is shown in Purple above, and in Blue on a more detailed chart below.  On first look, Patch might seem the slowest of the whole Trudeau bunch.  For example, since a catboat has no headsail, Patchogue has a terrible time pointing upwind; at  40° AWA Patchogue is still luffing, with a flat ‘zero‘ boat speed despite optimal sail adjustments. The Patch only comes to life around 44° AWA, and it then quickly jumps to its peak SOG between 50°- 60° AWA.   That performance still doesn’t seem much to write home about, even if your skipper hikes to windward and optimally adjusts the centerboard.

 But let me tell you: What I just said about Patch with wind speed= 5.0 m/s is far from the whole story; I mean first looks are often deceiving.  Far from being a slowpoke, Patchogue may actually be the fastest Trudeau since the Beach Cat once the wind speed  picks up. Reefing  is one of the reasons.

 Reefing

In real-life sailing, with increasing wind speed a boat accelerates and begins to heel due to apparent wind forces.  A wise skipper will often decide to ‘shorten sail’ under those circumstances. Taking down a sail or reducing the mainsail size by setting a reef point makes a boat more stable and easier to manage, while also reducing the risk of a capsize. Columbia and Patchogue emulate these effects by incorporating  reefing options that enhance the boat’s performance. Columbia has two reef positions; Reef One douses the top sails and  gives the boat a significant speed boost when winds are over 11 m/s AWS.  Reef Two is effective when the wind exceeds 13 AWS; it shortens the main and boosts boat speed performance even further.

The chart below shows these reefing effects in Columbia using a windsetter Real Wind speed (RWS) of 11.0 m/s. The Red curve shows the boat’s baseline performance without reefing. The maximum boatspeed occurs between 60°- 70° and is roughly 80% of true wind.  Not terrible, but nothing to write home about.

Sailing upwind with the windsetter’s 11 m/s RWS, the boat’s  apparent wind speed quickly jumps into the range where reefing is effective.  As shown in green in the chart below, adding Reef One greatly enhances boat performance on a close haul or close reach, yielding a maximum boatspeed equal to true wind at approximately 50° AWA.

If that’s not fast enough for you, Columbia’s got more; it’s got Reef Two, as shown by the Blue curve below.   In fact, Reef Two provides a truly explosive performance boost; at 40° AWA Columbia generates a boatspeed that is nearly four times the unreefed response and 40% faster than True Wind, and Patchogue’s Reef effects are similarly prodigious. Woots!

   

True and Apparent Wind Angles

If the huge Reef Two boost that I just described in Columbia and Patchogue has you excited, and you’re starting to dream about using it to blow everyone away on the the racecourse… please take off your sailing gloves for another minute so I can tell you the “downside.” Reef Two will make your boat go explosively fast, but “Never confuse movement with progress.”You pay a price for that speed boost.

 Since Trudeau boats are powered by apparent wind, as the boatspeed increases the apparent wind angle shifts toward the bow of the boat (due to the increased headwind) . If the windsetter is set for 11.0 m/s and a Columbia skipper tries to sail a heading of 40° AWA without reefing, as the boat speeds up the  corresponding Real Wind Angle (RWA) will settle in around 55°. Thats not so bad, although it probably means it will take a few extra tacks to reach the upwind mark. It’s hard to complain too much though, since the same problem occurs in real sailing.

 If a skipper now adds Reef One, the boat strongly accelerates, swinging  the apparent wind angle further forward. in order to maintain a 40° AWA heading, Columbia needs to sail a real wind heading of 75°. That angle means it could take a skipper twice as many tacks to make it upwind. 

Now comes the “killer.”  Under the same conditions if a skipper decides its taking too long to continuously zig-zag the way upwind and wants to go faster she can push the button labeled ‘Reef Two.‘ As shown by the chart above, Reef Two  produces a major surge in boatspeed at 40° AWA. unfortunately, to keep that heading a sailor will need to fall off the wind again… this time to a real wind heading of 92° at best.  That course is actually perpendicular to the upwind target. 

In case you find these numbers confusing, here is the bottom line: If a skipper is trying to reach a mark directly upwind, a Real Wind heading over 90° will never get you there.

Startline Tsurus.

Let me give you a practical example of this problem using the Blake Sea- Atlantic raceline. The default wind there is ‘spd 11.3 m/s, dir 170‘ and nearly perpendicular to the raceline, but with a 10°port-start bias.  Many racelines are similar. These default wind settings are actually pretty great for Real Wind boats like the Tako or ACA33. As evidence, here’s an overhead image from last evening, showing an ACA33 fleet crossing the start line.  The generous polar and lack of apparent wind effects allows most ACA boats to do a ‘point and shoot’ start, where a skipper sets a Real Wind angle of  25- 30°  and then sprints as fast as possible in a straight line over the Start. (Closing your eyes helps 🙂 )

 Pity the lowly Patchogue, however. 🙂 

Even starting from far back and over a sim away, as the Patch accelerates on a heading of 44° AWA towards the start line the apparent wind rotates toward the bow, and with Reef Two the real wind angle slides over 90°. Patchogue therefore slips past the raceline at high speed… and never crosses it.   

This turns out to be a particular problem at the Atlantic reaceline, since the windsetter default angle is 170° and there’s currently a committee boat ‘barging barrier’ in place at the Starboard end of the line. A Columbia or Patchogue skipper that is willing to underpower the boat just enough to make it across the Start will end up coming in nearly parallel to the raceline… and I know I am stubborn, but… I’ve yet to make it across the Atlantic raceline in a Columbia or a Patch without slamming headlong into that committee boat or the observation tower.  

Based on the above discussion, the little diagram below shows why. Real Wind boats can cut the line at a real wind angle optimum for their polar; In the Tako, that’s 35°. In Columbia or Patchogue, the approach angle is determined by the Reef setting and AWA.  As shown below, without a Reef Columbia can cross the line with a 55° RWA but has little momentum. With Reef One engaged, the boat can come in at a fairly extreme 75°  RWA, and with luck maybe get across.

 However, using Reef Two, the boat has to approach the line from the wrong side at an obtuse angle over 90°, and then gybe to port in the middle of the starting fleet in order to cross the raceline. And that’s assuming the skipper didn’t first splatter Awlgrip and gelcoat all over the stern of the committee boat just trying to get there.    

 

 OK, What’s the Fix?

 I think there are several possible fixes  for this problem.

  1. The easiest solution is to lower the windspeed for races involving Patchogue or Columbia. Spd= 9.0 m/s does not push the apparent wind angle over 90°  and should allow these boats to sail as part of  One Design or Big Boat fleets.
  2. Another possible option is to ask skippers racing these two boats to only use Reef One. They may go slower, but they will be happier.
  3. The real solution however, is probably to reconsider the polars for these boats, or at least revise the size and profile of the ‘speed boost’ caused by Reefing. Trudeau boats already have a upwind boost built into the unreefed polar, and the selective extra upwind boost provided by the two reef settings makes that rather extreme.  Let’s see what J Trudeau comes up with!

Having said all the above, I have to admit Patchogue is becoming my favorite boat to race and cruise… Given the number of races for this boat Now scheduled by Waypoint, Triumphal, Mango and Fishers Island Clubs, it looks like a lot of sailors agree!

Columbia First Numbers

A few weeks ago Trudeau Classic Yachts launched the much-anticipated Columbia,  Jacqueline Trudeau’s remarkable recreation of the legendary 1899/ 1901 America’s Cup racer. Columbia will replace JT’s venerable Defender in the TCY fleet line-up. This seems a remarkably apt swap, since Columbia also replaced Defender in Real Life over a century ago!

The new Columbia is the largest and most complex vessel in the Trudeau line, combining cruising style, live-aboard comforts, and steely-eyed race features.  Columbia even comes with a tender/ lifeboat that is a true thrill to sail in it’s own right.

There are so many issues and features I can’t give you an easy assessment of this latest Trudeau yet; I’m still getting acquainted with it. Nonetheless, I just couldn’t resist the impulse to share a few Columbia performance numbers as I’m settling in, and trying it out!

Regular readers of this column (all six of you) will probably recognize the above chart;  I’ve posted many versions of it before. It plots the steady-state boatspeed (“Speed Over Ground,” or SOG)  against different apparent wind angles using a fixed real wind velocity of 5.0 m/s.   Each curve shows the relative performance of a recent boat from the Trudeau fleet; the SOG for Trudeau Twenty is shown in yellow, Knockabout is in dark blue, Leetle Cat  in green, and J-Class is shown in red. I’ve now updated the chart to include Columbia’s performance, which is shown in light blue.

If you look carefully, you will see that Columbia’s SOG on upwind points of sail look  nearly identical to J-Class;   the light blue and red curves nearly overlap between wind angles of 20°- 90°.  The sharp initial slopes for each boat (under the 5.0 m/s wind conditions) reveals that both J-Class and Columbia generate a rather explosive increase in lift-thrust as the boats’ heading falls out of irons into close haul. Under light wind conditions there is easily a fourfold rise in SOG as the bow moves from 30° to 40° apparent and the sails fill.

 The sharp, early SOG peak on the above curves for Columbia and J-Class indicate that both boats probably have an optimal “velocity made good”  at a heading of 40°-50° apparent under light wind conditions. However, any sailor will tell you that optimum RL boat performance changes with increasing wind intensity. The curves in the above chart were all plotted using very light wind (5.0m/s), and can be misleading under more typical race wind conditions.

Heeling under close haul through Sailors Cove

 In real life (and in current TCY boats) as a sailboat accelerates upwind, the apparent wind velocity increases and the apparent wind direction swings toward the bow. The boat heels in response, and the sails become less efficient. In several Trudeau boats, the crew can set  optional ‘reef points’ to compensate for such strong-wind heel effects, with resulting enhanced performance upwind.

The chart below shows a polar plot of the J-Class ‘reefing effect’  (in pink), with real wind= 11.0 m/sec. You can see there’s a huge speed boost that’s largely confined to headings from 30° to 60°.

J-Class performance with reef effect shown in pink

Columbia has two reef points that also greatly enhance upwind performance under strong wind conditions. The chart below plots this effect on Columbia’s optimum boat speed for the three reef positions, given a real wind velocity of 11.0 m/s.

 

The yellow curve shows the boatspeed without reefing, and the maximum upwind SOG occurs at approximately 60° apparent. Reefing the sails not only increases boatspeed; it also lets the boat sail higher into the wind. Using optimal sail settings with real wind = 11.0 m/ sec., Columbia’s SOG at 34° using Reef Two is FIVE TIMES as fast as Reef Zero. Wowzers!

Reefing allows racers in SL to set a much higher heading for their optimal “Velocity Made Good” on a beat. I’m still collecting numbers, but my guess is that Columbia should have a target VMG around 34° apparent when sailing into a real wind of 11.0 m/sec…  but I have many more laps to do before I’m comfortable with that number!