Tuesday, July 26, 2022

Easy Winging?

 We went winging yesterday. After 8 wing sessions over the last 2 years, I finally came to the conclusion that winging could perhaps be easy, even for me. Sure, Nina makes it look easy every time, but in my first 7 wing sessions, it was hard work, every single time. There was just one session during an ABK clinic in Florida where I had a bunch of runs with decent control. But when I tried to reproduce that in the following weeks, my success was limited; even when I got up on the foil, it seemed way harder than windfoiling. I took another wing lesson during our recent trip to Cabarete, and learned a few more things - but my success was limited to maybe 50 feet of foiling before the inevitable crash. 

My tendency was to blame the gear, the conditions, or my slow learning. There's a bit of truth in all that -  it took me forever to figure out how to set up the foil properly for winging. But what really helped me was watching an instruction video:

This helped me realize that I had always been standing too far back on the board when trying to wing. I typically tried to stand in (almost) the same position as in windfoiling, except for the foil being mounted a bit more forward. But in windfoiling, there is extra weight pushing the nose of the board down that's in front of both feet: the rig (and any weight in the harness) pushing down on the mast foot. Trying to stand too far back means that the foil will be angled upward too much, and the nose of the board will be pointing too high. That often results in the foil just shooting out of the water, and a big splash when the clueless winger (that's me) hits the water half a second later. With a bit more "skill" and a lot more effort, the winger may be able to keep the foil in the water - but it's plowing through the water, which requires a lot more pressure in the wing to keep going. Which, in turn, give the (incorrect) impression that winging is hard work and no fun. But that's what I got in my first 7 sessions.

At least one of my two wing teachers, and probably both of them, had told me what I needed to do, but I needed to watch another video to really understand:

The key is that as the foil starts to lift the board out of the water, you need to do 2 things:

  1. Shift weight to the nose to flatten out the board, and reduce the angle of attack of the wing.
  2. Sheet the wing out - on the foil, you need less wing pressure than when trying to take off.
I tried exactly that yesterday, and it worked! Surprise? Not! Why did I not realize this earlier? I think my windfoiling "muscle memory" got in my way here. In windfoiling, one easy way to get on the foil once you are at take-off speed is to sheet out. That reduces the pressure on the mast foot and thereby on the nose of the board, angles the foil up, and lifts the board out of the water. Then, to push the nose down so you can foil at a stable height, just sheet in again. So, to stabilize the flight height after take off, you sheet in - the exact opposite of what you do when winging! 

My session yesterday was short, less than an hour (and quite a bit of that time was spent walking gear back upwind). But I managed to get on the foil in a controlled manner in every single run, and flattening out the board and sheeting out worked to keep the pressure in the wing manageable. Another key take away for me from the instruction videos was the placement of my feet. By angling the knees before standing up, it was easier to keep the feet close to the centerline. I'm not sure if I ever even checked where I placed the feet before; placing them further to the outside makes everything much more wobbly and uncomfortable.

A couple more things surprised me yesterday. One was that I was quite comfortable in relatively strong winds, with gusts in the mid-30s and higher (I winged between 12 and 1 pm):
The 4.2 wing felt perfectly fine, except in the strongest gusts near the end. If I had used a sail with the foil instead in these winds, it's quite possible that I would have been somewhat uncomfortable (I've done a couple of hundred windfoil sessions by now, but almost all of them were in lighter winds).

The other surprise was how easy jibing seemed. I fell in at least one of the jibe attempts, but also had a couple of dry jibes, including one where the board remain on the foil until past downwind. In another jibe where I set the board down on the water before turning, it came back up onto the foil when dead downwind. I was nowhere close to foiling through a jibe, but compared to the jibe struggles I still have when windfoiling, the wing jibe sure seems a lot easier. It looks like this time, I won't wait for a few months before trying this wing thing again!

Saturday, July 9, 2022

Gear for sale

There's too much gear in our garage that we don't use anymore, so we are putting it up for sail. This includes foil gear, a SUP that can be used for windsurfing (even beginners), and lots of windsurfing gear (boards, sails, and booms). All sales are pickup in Cape Cod, cash only. If interested, contact us on Facebook or by email or private message.

Foil Gear

2021 Starboard SuperCruiser foil (A-)  $650

Includes:

  • 1700 front wing, 370 rear wing, 87 cm windsurf fuselage, screws
  • 85 cm alu mast (standard) and 65 cm alu mast (for shallow water/beginners)
  • gear bag 
This is a great foil for cruising, suitable for beginners, in very good shape.

Armstrong HS850 A+ system front wing (B+) $420



Slingshot track adapter (new, unused)(A) $50

SUP / WindSUP

BIC AceTech 10.6 (B) - SOLD

Windsurf gear

Slalom/Speed gear

RRD XFire 90 slalom board (A-)  $400 (or $500 with 2 slalom sails)



The perfect board to go fast on flat water. Very easy to sail for a slalom board (but not a beginner board!). Very good condition.

Slalom sails: Hot Sails Maui GPS 6.6 and 5.0 (A) - $120 each



Both sails have seen very little use, and are in excellent conditions. $120 for one sail, $180 for both, or $500 for both sails and the XFire 90 board.

Slalom Sails: Maui Sails TR7 7.0 XT / TR8 6.3 (sold) / TR7 4.7 (A) $140 each




All sails are in very good to excellent condition. Buy one for $140, two for $200, or two and the XFire 90 board for $500. 

Windsurfing: Longboards

Mistral Equipe 2 with 3 fins (A-) $260


Great longboard for cruising and longboard racing. Very good shape. Can be used for teaching beginners.

Fanatic Ultra Cat (B) $200

Beautiful classical longboard, 1987 design. Tons of fun in light to medium wind. Nina won lots of races on this board.

F2 Lightning (B-) SOLD

Windsurfing - Miscellaneous 

2018 Fanatic Skate 86  (A) $850


Bought 2019 and not used much, since Nina started winging in 2020 and has not used it since then.

2011 Fanatic Skate 90 (B-) $300



This board has twin tracks for foiling, in addition to the original power box. Nina started foiling on this board.

Mark Angulo Custom 72 l (A) $450

Mark Angulo built this board for Nina when we stayed on Maui for 6 weeks. She used it only a few times since then.

Slim carbon boom (Goya) 130-180 (B) - SOLD

Slim carbon boom (Aeron) 150-200 (B-) SOLD

Sail: North Idol 4.0 (B+) - SOLD

Sail: North Ice 3.4 (A) - SOLD





Thursday, June 30, 2022

Small Steps and Fast Foils

Foiling jibes are hard, if you ask me (just don't ask Nina). I've spent countless our watching instruction videos; have taken camps and private lessons with one of the best foil instructors in the world; bought new foil boards hoping that they would solve my jibe problems; and tried jibing on the foil often enough that I discovered dozens of ways to screw it up. But I still cannot foil through jibes consistently. 

Here are some of the things that I remember from various lessons and videos:

  1. Use a wide board, it's easier (my Stingray 140 qualifies!)
  2. Take a big step close to the rail to start the turn. That's suggested in many videos, except that Nico Prien suggested a smaller step closer to the center line.
  3. When it's time to switch feet, step heel to heel, bringing the old front foot to the back foot. 
  4. Move the old back foot straight into the new front strap.
Can you spot the problem? When I followed step 2 and took a big step, then my crashes in step 3 would be virtually guaranteed, and often scary (like the one where I fell onto the foil with the back of my head .. in case you wondered why I now always wear a helmet). I've blogged about my problems with step 3 before, step 4 remained a pipe dream - I count it as a success when I step on top of my foot straps, instead of landing in front of them, as I usually do (which is 100% effective at dropping the board onto the water).

One issue that I could never wrap my head around was this: if I take a big step to the outside rail, and then try to bring my other foot heel-to-heel, that's also a pretty big step. While taking the second step, all my weight is near the edge of the board, and the board is above the water - meaning it is very tippy. Maybe I'm just to slow? But whatever it is, the board would tilt as if I was trying to start a rail ride, and I'd have to hope that my fall would be away from the foil.

Things finally started to click when I watch a video about the One Hour Classic at Lake Garda:

About 45 seconds into the video, the boat close to the jibe mark captured great footage of several foil jibes. Everyone is on a wide board (#1), and everyone does takes a wide step to the carving rail (#2). But when it comes to moving the old front foot to the back, nobody follows rule 3! Instead of a single step, every single racer takes multiple steps with the new back foot. The first step is a small step out of the front strap, a bit to the back and towards the center of the board. This is immediately followed by the carving foot sliding forward a little bit into the foot strap. After that, there are one or two additional small movements of the back foot that bring it to the other side of the board. Except for the first step onto the carving rail, all foot movements are small.

Considering that the flying board is very reactive, and that we don't want to unsettle it while switching the feet, these multiple small movements make a whole lot more sense than a single big step! I went back to look at some of the instructional videos I had watched, and in most of them, the instructor also takes multiple steps to move the old front foot to the new side. They just don't ever talk about it. All those foilers who learned the foil jibe relatively quickly must have either noticed it, or figured it our on their own. But I know I'm not the only foiler who has a hard time learning to foil through the jibe!

So I'm excited about trying this our in my next foil session (and to try some ideas I have about the tack footwork, too). But I also found it quite exciting to read that at the One Hour Classic, foils were significantly faster than fins. The winner in both fin and foil categories, Jordy Vonk, completed 21 laps in the foil race, but only 19 laps in the windsurf race. The recorded top speeds were also faster for the foils, with 33.59 knots vs. 31.84 knots for fins. Just as amazing was the average speed of 27.4 knots for the hour. On the GPS Team Challenge, the fastest 1-hour result ever posted for the US was about a knot slower (26.46 knots by PWA sailor Taty Frans on slalom gear). So an average speed of 27.4 knots with 20 jibes in Lake Garda chop is pretty amazing! 

Saturday, June 25, 2022

GPS Speedreader 2

 I have just posted a new version of GPS Speedreader at ecwindfest.org/GPS/GPSSpeedreader.html. Since this version adds a feature specifically for dual GPS units, like the ESP/e-ink loggers I mentioned in my last post, I changed the version to 2.0. This version also has a few additional new features, including support for the FIT file format, which is used my many GPS watches. In this post, I'll explain some of the new features, and give examples where they help to improve the accuracy of GPS speeds.

"Intelligent Averages" for dual GPS units

When a speedsurfer in Belgium developed a cheap DIY GPS unit with an e-ink display that can be mounted on both sides of a boom, making it easy to check the current speed when windsurfing, my friend Mike from the GPS Team Challenge suggested to calculate speeds as averages of the two GPS units. In theory, the average of two separate measurements should be more accurate than a single measurement. We discussed a few ideas about how to calculate the averages, and came up with "intelligent averages". Let's first look at some speed data from a recent foiling session:

The two GPS units mounted on each side of the boom gave nearly identical speeds for the vast majority of points. There were some ups and downs, but they were well synchronized between the units, which indicates that they were probably real changes in speed. Sometimes, these speed changes may be due to boom movements - pumping, for example, is easy to spot. In the graph above, the little spike as the speed drops is due to moving the rig during a tack. When data look like in the graph above, speed averages will be very similar between the two units, and the averages will also be very close.

But that's not always the case. Here is another example from a top-10 second run from a different session:

Here, the green speed track shows a couple of pronounced spikes. The little inset shows the speeds and error estimates for the first spike. For the two points where the green speed is about 1.5 knots higher than the red speed, the error estimates are roughly 50% higher for the green data. Since one of the two tracks is clearly more accurate than the other, it does not make sense to calculate a plain average - instead, GPS Speedreader uses the only speed of the more accurate data. That's the "intelligent" part of the "intelligent average" (the blue lines).  Not really hard, so maybe "not dumb" would be a more accurate description, but "intelligent" sounds better.

In the example above, there was a reason why the green GPS had worse data than the red: the green GPS was using only 2 satellite systems (GPS + GLONASS), while the red GPS unit used 3 satellite systems (GPS + GLONASS + Galileo). In the region shown, the additional 5-6 satellites from the Galileo system helped the GPS to be more accurate.

The effect of the artifact in the picture above was small, between 0.1 and 0.2 knots over 10 seconds. But sometimes, we can see much larger differences between two boom-mounted GPS units:

This section is from a crash, where the boom side that the red GPS was on ended up under water, and the boom side with the green GPS stayed above water. Under water, the red GPS lost track of most of the satellites, at times only being down to just 3 or 4 satellites. In contrast, the green GPS stayed above water the entire time, and kept tracking 16-17 satellites. The green GPS correctly reported that my speed dropped from 15 knots to almost 0 in less than a second - but the red GPS kept reporting speeds around 15 knots, eventually even increasing to 27 knots. Very interesting, considering both GPS units were attached to the same boom!

This is very typical behavior for u-blox GPS units in windsurfing crashes. Keep in mind that GPS chips were developed for cars, not for speedsurfing. Cars very rarely end up under water, and when they do, GPS accuracy will be the last thing the driver worries about. But cars often drive under bridges or through tunnels, where they loose GPS reception for a short time. In these situations, the "dead reckoning" behavior that the GPS chip shows is perfectly reasonable - most likely, the car will keep going at about the same speed. 

But in windsurfing crashes where the GPS ends up under water, things are different, and GPS chips that "fantasize" about steady or increasing speeds can be a problem. If you look closely at the data in this example, you can see that the error estimates rose quite slowly after the crash - it took almost 8 seconds before the +/- estimates reached 4 knots. An error estimate of 4 knots happens to be the default value for speed accuracy filters in older versions of GPS Speedreader, since this threshold makes sense for Locosys GPS units like the GW-60 watch. But for u-blox based GPS units, it it much too high, as this example shows (and I have seen examples where crashes led to incorrect GPSTC postings, and at least one false personal best).

In GPS Speedreader version 2, this problem is addressed by using different accuracy filter thresholds for u-blox based data. For typical u-blox data (5 Hz or higher), the accuracy threshold has been reduced from 4.0 to 1.2 knots. In the example above, this filters out the speeds in cells with a red background (the blue line is where the error estimates exceeds the old threshold of 4.0). The file format is used to determine which threshold should be used - .ubx and .aoa files use the u-blox threshold, other file formats use the higher (Locosys) threshold.

While it is uncommon for "dead reckoning artifacts" after crashes to lead to errors in top speeds, these artifacts can often distort the total distance for a session. The use of dual boom units and the "intelligent averages" practically eliminates this problem, since at least one of the two units will typically keep good satellite reception, and therefore report accurate speeds.