Friday, November 19, 2010

Canadian Windsurfers...

You can say all you want about how lame Facebook is, but when it comes down to bringing together like-minded individuals on a cause, it has rapidly become the undisputed King.

Ilan has set up a Facebook page for Canadian Windsurfers. Check it out here.

Hopefully this page can act as a bit of a resource to reach out to even more people, from Canada or abroad, to join the Canadian Windsurfing Community in addressing issues of access, water quality, safety, you name it, things that effect us windsurfers in Canada.

The most recent problem is Air Canada's baggage regulations and their prohibition of windsurfing gear on its flights. Not only can you find some info on the new facebook page, but if you'd like to sign a petition to work towards overturning these regulations, please go straight here:

I sure wish this was around when we were attempting to deal with Transport Canada and their dumb-ass PFD requirements...

Friday, November 12, 2010

Wave Theory and Principles Interpretted. Part II

div>In Part I, I just spoke a bit about a few terminology clarifications, how wind duration and fetch affect the quality of the waves and also a few tidbits on wave power and speed.

Here's a beauty hack at the lip by Pierre Morneau from Montreal, at Sandbanks last fall. Great shot by Nic Chapleau. Pierre rips.

Part II is all about wave transformation, or, how a wave changes when it encounters features in the lake, sea or ocean, things like the bottom, the shoreline and man-made structure. This is the magic that makes a place like Sandbanks work for us! But, I do stop short at wave breaking, which I will leave to a bonus Episode III - joy for all!!

So, to continue with the lecture; As waves begin to enter shallower water, they begin to ‘feel bottom’, and start to transform. Their motion and progress becomes compromised by the bathymetry (sea floor topography) and shape of the shoreline.

Deep-water waves (within small amplitude wave theory) are basically comprised of water particles making circular motions. The diameter of the rotation is largest at the surface and gets smaller as you go down from the surface, to the point there is no movement at a depth of roughly half the wavelength. The next diagram shows these orbits in both shallow and deep-water, but it is perhaps better understood looking at Fig9.5 in this Google Book, called Essentials of Oceanography by Tom Garrison (I didn't want to copy it in here due to copyright infringement, but its a good little diagram).

So, when I talk about waves "feeling" bottom, it means that the bottom is interfering with the orbit of the water particles and hence the orbits become non-circular, and more horizontally stretched as ellipses. Again, keep in mind this is all theoretical and not a whole lot in real-life will look much like this due to so many other factors.

Here's one of my faves of me from last year, by Ilan Artzy. I like the spray on this bottom turn. Not a huge wave or anything like that, but a fun one nonetheless.

Two things happen when waves begin to interact with the bottom: 1) Refraction & 2) Shoaling.

1) Refraction. Wave refraction is a change in direction of the wave due to a change in speed. Picture in your mind a wave coming side-onshore (like in the photo below, from the southeast). As the wave front/crest starts to enter shallow water, it will begin to slow down. Now imagine this happening along the whole wave crest. The wave crest will start bending since the part of the wave nearest shore will have wrapped/bent more than the part of the wave further offshore (because it has slowed down the most).

Ultimately, waves tend towards shore such that the wave crests will ultimately strike parallel to the shoreline (or in different terms, the wave ray will tend towards perpendicular to the shoreline).

The end result is that waves bend to become almost perfectly onshore by the time they hit the actual shoreline. See image. For those Sandbanks regulars – this is very important to us!!! Without refraction the wave action at Sandbanks would be pretty damn lame – it is the refraction that turns on-shore conditions into our pseudo-'side-shore' conditions.

And here is a diagram of a wave wrapping around an island. Suffice to say that sailing in lee of the island would suck for a couple of reasons: No wind & messy waves!

2) Shoaling. Another thing happens when waves start to touch bottom. As the bottom begins to interfere with the circular motion of water particles under wave action, the shape of the waves begins to change and this is called shoaling. The shallower the water gets, the more the waves shoal, or bunch-up and steepen (jack up) until ultimately they break. This is a pretty intuitive transformation that most anyone who has watched a wave will recognize and understand: As waves approach shore, they will appear to jack up and get bigger and ultimately break in one form or another. The bigger the wave, the further out it will break. It is pretty obvious to most people that the bigger waves at Sandbanks are further out from the beach, or further upwind near West Point, because they haven't shoaled as much, or for as long, and thus have more of their original energy left.

Here is a wiki on the topic of wave shoaling, with a really neat little graphic that shows the process and impact of shoaling on wave height and wavelength (By Régis Lachaume). See below (its a 2Mb .GIF, so I hope it uploads for you).
(ahh, sorry, looks like animated .gifs don't work in Blogger blogs...)

Another couple of things can happen to waves as they travel through water. They can interact with features they encounter. The refraction and shoaling mentioned above fit this category, with respect to natural shorelines and lake-bottom. Another couple examples of wave transformation are: 3) Reflection and 4) Diffraction.

3) Reflection. If you have ever had the pleasure of sailing in front of the ‘PUC dock’ in Kingston, you’ll know what this is all about. In fact, this is what makes Emily St (Richardson Beach) in Kingston much messier than locations further upwind. When waves strike an object that is unable to absorb its energy (virtually all things), some amount of the wave energy is reflected, or bounces back off that object. This can happen straight on or at an angle to the object. When a wave hits something like a concrete vertical breakwall head on, a considerable portion of the incident wave energy can be reflected back from whence the wave came. This creates a nasty mess of standing waves, or waves that appear to be stationary and pop out of no where. You don’t want to be sailing anywhere near there unless you are experienced in rodeo. All surfaces do reflect some energy, even a sand beach. The least wave-reflective shorelines in nature are likely extremely long, gently-sloped sand beaches and vegetated shorelines such as coastal wetlands. Anything man made or hard tends to reflect energy in a nasty way. So, a big two thumbs down for shitty breakwall design!!

4) Diffraction. Diffraction is the bending of waves around an obstacle in their path, or through an opening. I won’t talk much about this but it is a pretty neat phenomenon. One of our most beloved bloggers Giampaolo (Maui Surf Report) mentions the odd surf session scored in Kahului Harbour. Since I have never actually seen the spot, I looked it up on Google Maps (in fact, I used a NOAA free website called 'Geogarage Marine', which can overlay available marine bathymetry charts under Google Maps aerials - really neat!) . Generally, as waves enter a harbor gap like that, they start to spread out radially from the entrance, resulting in a down-size in wave and wave power as the energy disperses through the harbour. Think of it this way: You have a harbor gap that is about 200ft wide that allows energy to pass through and then dissipate throughout a harbor that is about 1000ft wide or more. I imagine when huge waves are pounding the North Shore of Maui and closing out everything, maybe that harbor still works for surfers since the waves go from deep to shallow fairly quick and the big stuff doesn’t make it through, plus you may have smaller waves getting in, wrapping nicely. Just a guess.

Alright, so the next few photos are just some gratuitous shots from Sandbanks, and don't have a whole lot to do with anything except for waves!!

Bottom turn by Pierre (photo by Nic):

... and heres another shot from last fall. Nothing spectacular about the action, but just looking past that to the bomb in the back that no one is riding!!

Wave Theory and Principles Interpretted. Part I

Following on my undergraduate education, I studied coastal engineering in more depth for my Masters of Science degree. This is part 1 of a 2 part blog post on some of the basics of waves.

A lot of good useful information for us windsurfers comes from “Small Amplitude Wave Theory”, which is one of the most simple and most widely applicable mathematic principals for quantifying the movement of waves. There are many other theories as well, each having their place. I studied this stuff for a few years, way back in my university days and have forgotten most of it, aside from the basic principles that apply to our beloved Lake Ontario. Despite immersing myself in Coastal Engineering, somehow I still ended up living on a lake, rather than say an ocean, where arguably I should be residing. But, I digress…

Here's a shot of Guy Trudeau at Mac's last year, taken by Nic Chapleau. Looks like a sweet wave to me!

Here is a link to the wiki on the topic.

So, without getting into all the crazy math containing far too many greek symbols, which I have long since forgotten anyway, here are some of the more basic wave principles and observations I took away from all this education, as they relate to Lake Ontario and Sandbanks.

What is 'Swell'? First off, some terminology: Lake waves, by definition, are not “swell”. Lake waves are more accurately referred to as “locally-generated seas”, or in other words, waves produced by the action of the wind itself, locally. Some refer to this as “wind swell”, which kinda makes sense, but there is actually no true "swell" on the Great Lakes. Swell, by definition, is wave action created by distant wind events. By travelling long distances and moving away from the storm, the waves become much more organized with longer periods, wavelength and speed. In particular, storms send their higher energy, lower frequency waves further abroad, and this is true ‘swell’. Despite the Great Lakes being pretty dang big pools, they are generally too small for true ‘swell’, and generally too small for tides as well.

Consider this to be the first problem for us windsurfers. In the Great Lakes, it means that waves and wind will generally travel in the same direction = on-shore conditions. In a place like the north shore of Maui, waves are often direct onshore, while the wind is sideshore - a much better recipe for fun.

Fetch. The wave period, height and degree of wave organization is also a function of fetch (distance over which the waves can develop) and duration of the storm. The longer a storm blows, the more organized and longer the waves become (tending towards a "fully developed sea"). At Sandbanks, if a really good storm whips up, we usually get 5-7 second waves. Heaven forbid it should blow for a day or two straight, we may even get up to 8s waves, in which case let the ejaculation begin.This is the ‘peak’ wave period, or the period of the wave spectrum with the most energy. The peak wave period can be either wind duration- or fetch-limited. In the case of Sandbanks, the limitation rapidly becomes fetch – we’ve got 200km at best. Anyway – this has two impacts: First, the waves are generally a lot messier than ocean swell since there is a fairly broad ‘wave spectrum’, in that there are waves with all sorts of different frequencies (periods) and directions out there, interacting with both positive and negative interference. Second, the biggest and best waves are still relatively small and limited in wavelength, meaning the waves are spaced fairly close together.

Getting beat down. Speculation: I believe that a good indicator of what we feel when we get shmucked by a good wave and have our gear and gitch extracted from our clenched bodies, is wave ‘power’. Wave power is a function of wave period and height squared. So don’t think you can dominate the pesky 7 second waves at Sandbanks, then cruise on in to Ho’okipa and own the place. Typical true ocean swell there is probably more like 10-15s, and up to 15-25s on the big gnarly days. That’s why sailors like us from eastern Canada get pummeled and really feel it when we go to Hawaii. It truly is bigger and much bad-er!

Bigger waves + longer period = considerably more power, which in general means more “F$%^ you up” potential.

Here's a shot of me with a weak bottom turn at Mac's last year, by Nic Chapleau. Despite looking like a nice head-high wave, they are pretty gutless. Damn fun though!

Wave Speed. In general, the longer the wave period, and hence wavelength (these are related), the faster the waves travel. While waves do slow down as they ‘touch bottom’ and diffract (wrap) and shoal (‘jack up and break’), to be discussed in Part II, this trend still holds true. In Sandbanks, on the good days, one of the bigger shortcomings to the otherwise stellar front-side riding is the speed of the waves – they are simply too slow, making it fairly easy to outrun the waves on bottom turns, making it a lengthy and challenging approach back towards the wave to shmack the lip. This has a great potential to result in backwinding. While at Sandbanks, the psuedo-‘side-shore’ conditions (wave vs wind direction) are partly to blame, but so is the slow speed of the waves.

Here's a wee shot of JFLemay at Mac's, by Nic Chapleau:

Anyway, that is Part I of my blog-length dissertation on some basics of wave terminology and physics as it applies to real-world observations. Some of it straight out of the literature (interpreted by me), and some of it based on real-world observation in alignment with principles I have learned. Part II gets a little more 'interesting' and talks about wave wrapping and breaking...

Here's a shot by Ilan Artzy from the beach. This is all totally onshore...

Please let me know by posting a comment if this type of blog post is at all interesting or just too damn dry and boring. I tried to interject the science with the odd photo of some of the more decent waves from Sandbanks. Most photos courtesy of Nic Chapleau (unless otherwise noted), and the text-book images are all from the USACE Coastal Engineering Manual –Part 2. I had to buy an older version of that manual back in Uni for well over $100 so I don’t feel bad at all about snipping pieces out of the new on-line version. That was a lot of frickin' beer money I will have you know... Let’s hope the US military doesn’t come and send a drone over my house.

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Wednesday, November 03, 2010

Multi-Fin boards - Will we see any around here?

So, any windsurfer who picks up a magazine or even glances at a computer screen will have noticed that multi-fin boards are everywhere (unless perhaps your brain is broken). Where as 3 years ago there were zero companies marketing multi-fin boards (aside from perhaps a few custom manufacturers and HiFly), now there are probably zero companies WITHOUT a multi-fin board in their production line-up. In this most recent wave/craze for multi-fin boards, it appears twins came first, followed rapidly by quads and perhaps thrusters and all sorts of variants. Certainly proud to say QUATRO was at the forefront of this development! I am sure there are different perspectives how and who led this recent industry push to multi-fins, and I am no expert... nor do I care to be.

I love this photo by the way:

Anyway, I am curious what Great Lakes and non-ocean sailors think of these boards. Very curious to see if they will start popping up here and there. What do you think? Do they have a place in our quivers or are they just too specialized for us to get our money's worth?

In most cases, I reckon it will be the lads who maintain recent gear who would be most intrigued and most tempted. In one regard, those individuals are the least likely to feel daunted by the risk, since they typically turn over their equipment every 1-3yrs. On the other hand, they gotta be worried a bit about re-sale given the questionable applicability to real-world/non-ocean conditions and how long this multi-fin trend will last. It may not be so easy to sell a multi-fin board, because of the conditions we sail for starters, but also due to changes in trends in the industry. I am in this category, for now.... Tempted, but very dubious... and my gear turn-over rate is dropping fast with these children who need to be fed.

On another note, Tabou has been producing a twin-fin freestyle line called the Twister. In one sense, one can certainly understand that in the drive to make a board work with the smallest fin possible (for freestyle trickery), the notion of twin-fin would allow those fins to be that much smaller (albeit with two of them). Does anyone have any experience with twin-fin freestyle boards? How do they compare?

Back to the wave boards. As I say, I am tempted. Recent days in quality waves at Sandbanks certainly have me pondering. One thing for sure, I wouldn't even glance at any multi-fin board unless, at minimum, it would perform reasonably well in on-shore and straight-line high-wind bump. Err, well, OK - I would probably glance at it, drool, then look away to something else.

For interest, just did a test of ~85L waveboards. Check out the article here. Gotta hand it to Boardseeker, they do some pretty good testing so far as I can tell.

The stick that appears to come out with top marks from the test is the Goya Quad, for quite a wide variety of user abilities and wave conditions. Its main weakness, unfortunately - straight-lining and B&J. Next in line, perhaps the Quatro Tempo - pretty damn good in all wave conditions, but also shining in top-end and B&J amongst the tested board. Maybe that is just my interpretation of the results, but hey, of course I am biased. Next in line, the JP Thruster.

So, testing indicates that maybe, just maybe, multi-fin boards can also work for high-wind B&J, admittedly probably the biggest use of smaller waveboards in this neck of the woods.

What do you think?

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