Saturday, July 24, 2021

Foil Jibes, Big Feet, and Forgetfulness

Back in February, I posted about a foil session where I had tons of good foil jibes, thanks to help from Andy Brandt. I should have known that would not last! After all, Andy also taught me how to plane through windsurf jibes ... and then, I had to take another dozen ABK camps where he had to jog my memory how to jibe properly. He was usually able to fix my problems within an hour. But in the weeks and months after a camp, I'd start forgetting, and went back to practicing bad old habits instead.

Windsurfers have to be optimists, so I hoped that this would not repeat itself with foil jibing. But whenever I tried to jibe back home on Cape Cod, a typical result would look like this:

Well, perhaps not always this flashy, but usually wet. Which is a real bummer, since I got that faster foil which really calls for using big cambered sails - sails that I really do not want to waterstart or uphaul all the time!

I was coming close to resigning myself to a lifetime of foil tacks when my endless hours browsing windsurf and windfoil forums paid off. A fellow foiler whom I had met in Corpus Christi posted a picture on Seabreeze that illustrated what had helped him to foil through jibes. The key was to have both feet pointing forward, towards the nose of the board. So a couple of foil sessions ago, when my initial foil attempts had resulted in the usual crashes, I tried his tip. Immediately, my jibes remained dry! They may still have been ugly as hell, with lots of wobbling, but at least I was not falling anymore!

A look at the GoPro footage from the session reveals that the differences in foot orientation were much smaller than I thought. Here's how my feet were placed in the initial crashed jibes:

Note that the back foot is almost perpendicular to the long axis of the board.
For comparison, here's a screen shot from a later (dry) jibe where I tried to have the toes pointing forward:

The difference in foot orientation is much smaller than I thought - maybe a 20 degree difference for both front and back foot. The feet are also closer together in the long direction of the board, as can be seen by looking at the distance from the front heel and the back toes to the black line on the board. This means that smaller steps are required during the foot change. Together, these changes made the "dry rate" in the jibes go from 20% to more than 80%. So far, so good!

Thursday was another great day to work on foil jibes at Kalmus. Just check out the wind graph:

Some Kalmus windsurfers may want to point out that northerly directions are not so great at Kalmus, and use the lulls of 5 mph and gusts up to 25 mph as "proof". But then, neither would they go out in the 10-13 mph averages that we had at the beginning of the session! But northerly wind directions are offshore at Kalmus, meaning the water is very flat. Just perfect for jibe practice! You don't need to be an expert to enjoy the conditions, either - Joanie, who is still a foil beginner, had some very nice long foil rides today with her 5.4 m sail. 
My only goal for today's session was to focus on the foot work in jibes - the initial setup with feet pointing forward, and a smooth(-ish) foot switch. I jibed 15 times in the 2 hour session today. 14 of those jibes were dry, which I am quite happy with. Some where nicer than others; today's GoPro footage was quite useful to get hints about what might cause the problems, and what to try to fix them.

In a few of the uglier jibes, the sail flip felt very unbalanced, and I often had to grab the mast instead of going boom-to-boom. Here's an example screen shot:
That sail has gotten away from me, forcing me to bend over. But why? A look at the board gives a hint: the leeside edge of the board is in the water. That means that the board is carving in the wrong direction! That's clearly visible in the GPS data for this jibe:

During the sail flip, the board turns back by about 15 degrees within one second. That does not really help to complete the jibe! But worse, it puts the sail in a pretty bad position - it's pretty much flagging out to the front of the board. No wonder something felt off!

To understand why this happened, we can look back a bit further in the video:
Check the placement of the old front foot as it is stepping back. The entire foot is on the wrong side of the center line - the lee side. As soon as I lift the old back foot to step forward, this will reverse the carving direction of the board! 
For comparison, here is the foot position at the same point in one of the better jibes of the day:
The new back foot stepped about a couple of inches closer to the old back foot, which makes it straddle the centerline of the board. With weight on the heel of the new back foot, the board will keep turning the right way even as I step forward with the old back foot. Indeed, the GPS tracks for this jibe show that the board kept carving about 10 degrees, from 148 degrees to the wind to 138 degrees. That's 25 degrees better, just because the foot placement is a couple of inches different! With the board continuing to turn the right way, the sail flip on this jibe was easy:

Maybe the jibe was not perfect, but I was able to keep the speed above 7 knots, which let me get right back onto the foil after the sail flip - good enough for me!

So the question arises: how can I make sure that the front foot steps back to exactly the right place? One possible solution would be to put the older carving foot further to the outside of the board, so that there is more space for that big front foot as it steps back. But when I tried this in the past, a new problem occurred: when lifting the old front foot to step back, the board tilted a lot, which often resulted in a crash. That sometimes made for great screen shots, where it look like I'm trying rail rides with a foil - but it did not make for dry jibes. In other tries, I would feel the board starting to tilt when the old front foot started to move, and I'd cut the step short to prevent the board from tilting. That, however, would leave it on the wrong side of the board again! So while the tip to "move the carving foot all the way to the outside" may work for some foilers, it does not work for me.

But let's have another look at the last picture above, where the sail flip worked well enough. You can see that both of my feet are in front of the foot pads - in other words, too far forward. That means that the board will go down and touch the water, and won't start flying again until I moved both feet back again. For the goal of fully foiled jibes without water contact, that's not good enough. It is, however, very typical for my "good" jibes: even in my session in Corpus Christi, where I almost foiled cleanly through many jibes, the board would often touch touch briefly just after the sail flip (or, in sail first jibes, the foot switch).

So I really have two problems, let's call them "wrong side" and "too far forward". My lovely wife never experienced these problems, and I think that's simply because her feet are a lot smaller, so it's much easier to find space on the board. Unfortunately, blaming my big feet does not really help. What might help, however, is stepping heel-to-heel, making sure I feel the foot that moves back actually touch the heel of the old back foot. That would place the back foot a bit further back, and the heel on the correct (windward) side of the centerline. If we now assume a constant size for the step forward, the front foot should also end up a bit further back. That would be progress.

But one of the things that I glossed over somewhat was that in the initial setup, I move the feet closer to each other in relation to the long axis of the board: the back foot goes forward a bit, and the front foot goes back a bit. That allows for smaller front-to-back steps during the foot switch, which in turn leads to a steadier flight. To "undo" this, it may be necessary to modify the foot placement during the switch: the old front foot steps behind the old back foot (but still heel to heel). That should make it easier to keep the old back foot from stepping too far forward, and it also should give the foil a little push up to get flying again, or to keep flying. I can't wait to get back onto the water to try!