Colas.Nahaboo.net - surf

10 minutes full SUP and Surf Warmup video, v9

2026-04-22T00:00:00+00:00

This is my 10 minutes warmup routine before my morning SUP session, version 8. Follow-along, 10 minutes exactly, no intro/outro.

https://youtu.be/4FUwYA6NgWs</a>

</iframe> </div>

Altough I insist on things important for SUPing (calves, trunk twists, burpees) it can be used as a warmup routine for all uses. No commentary nor music track as I do not want to wake up the house on my dawn patrols :-) Add yours if you want to.

As I am 65 yo, and I SUP/surf very early to avoid crowds, I need a full 10 minutes warmup to avoid injuries. I thus do it at home just before driving to the beach, otherwise I could not discipline myself to do it on the beach. If you are younger, or before an afternoon session, just play the video at 2x speed for a 5mn quicker warmup :-)

This 10-minute warmup video provides a series of 30-second exercises designed to activate the muscles and joints. The goal is to lubricate the joints, to warm up, not to reach maximum flexibility. Avoid pushing into full stretches. Use furniture for support if needed to ensure a safe range of motion.

It is a compilation of 30 seconds sections, copied from the Youtube warmup videos below (in order of appearance). Refer to them for details and explanations.

Calves: https://www.youtube.com/watch?v=7Zs4hh4cp98</a>

Lunges front: https://www.youtube.com/watch?v=79yebGL3NX0</a>

Ankles: https://www.youtube.com/watch?v=kRwSyXzVtNk</a>

Trunk Twists: https://www.youtube.com/watch?v=LqdvhvePVFU</a>

Full Body: https://www.youtube.com/watch?v=VecbXgWY0DI</a>

Hip rotations: https://www.womenshealthmag.com/fitness/g26554730/best-warm-up-exercises/</a>

Lunge Twists: https://www.youtube.com/watch?v=6jy4HYOhRmI</a>

Burpees: https://www.youtube.com/watch?v=yewKJShD1EU</a>

New in this v9:

The countdown timers were missing in all sections!</li>

This v9 replaces the v8 version at: https://youtu.be/Bwe6kBA-sPc</li> </ul>

Wetsuits chest zip direction: reverse!

2026-03-24T00:00:00+00:00

I used to buy mostly Rip Curl wetsuit, and when they decided to reverse the chest zips, I was puzzled, but after the first session, I was convinced:

Chest zippers must open towards the inside

Normal direction: Bad!</figcaption> </figure> </label> </div>

Reverse direction: Good!</figcaption> </figure> </label> </div> </div>

Why?

Reduced stress: The natural tension on the wetsuit doesn't pull the zipper open. This eliminates the need for a cumbersome stopper or a snap button, as it cannot come undone on its own in the water.</li>
Greater range of motion: The "inside" end of the zip is free from the bulk of the starting mechanism, allowing for a wider opening. This makes getting in and out of the suit noticeably easier.</li>
Durability: The stress of entry and exit is concentrated at the "open" end of the zipper, where it is less likely to cause damage.</li> </ul>
The picture on the right is of my Feral wetsuit. It’s an excellent Yamamoto neoprene suit, but it is cut a bit smaller in the chest than other brands. Because of this, I actually blew out the zipper during only my second session—something that has never happened to me before.
I had it reversed by a local repair shop (the excellent All-In repairs</a>), and the difference is staggering. The wetsuit feels noticeably looser and more comfortable in the chest!
My advice:

Prioritize wetsuits with reverse zippers.</li>
Standard zippers can be reversed by your local wetsuit repair specialist.</li> </ul>

Repairing a broken leash on the water

2020-12-28T00:00:00+00:00

I have found a simple to do and easy to remember method to repair a broken leash cord on the water. Just grab the broken bits parallel in the hand and do a simple overhand bend knot, one of the simplest knots around. The trick is just to pull the knot really, really tight hard before resuming the surfing session.
Of course this not a permanent repair, as the knot will add drag to the leash, but it is enough to finish the session securely.
Image courtesy of netknots:

See the full animation at netknots</a>
Here is the result on a leash broken leash during my session:



Note: I first posted this article on seabreeze</a> </blockquote>

The Donaldson trailing edge, no more fin hum!

2020-07-07T00:00:00+00:00

At last, I have found a good video explaining how to suppress the vibration of fins and foils, and giving the name of this technique : the Donaldson trailing edge, described in 1956 by ... Donaldson
Up to now, I had only seen the diagrams for symmetrical foils (just sand only one side, not both) but this video goes into the details and show that you must sand the inner face of asymmetrical foil (flat one), not the curved one.
Thanks to Mario Legenstein from Levitaz for the video: </iframe>
I thus also learned that the effect causing the humming is "Vortex Shedding", aka the "Von Kármán effect</a>". On thick trailing edges, vortexes are created alternatively on the two sides of the trailing edge, and they push and pull on it at a frequency depending of the speed and the edge geometry. These alternating forces make the foil or fin vibrate and hum.
You can google "Donaldson trailing edge" to find many detailed references. For instance:
Boundary layer effects on the vortex shedding in a Donaldson-type hydrofoil</a>
Vortex shedding from blunt and oblique trailing edge hydrofoils</a>
And these wind tinnel images show the alternating vortexes creating the vibrations on a blunt edge on the left, and how the Donaldson edge locks the vortex in place on the right:
Here is a comparison of the amount of vibrations for different shapes of the trailing edge:
This von Kármán effect is what makes ropes whistle in the wind, can destroy underwater pipelines, and can destroy bridges when they vibrate in sync with the wind, such as the famous Tacoma bridge: https://aerospaceengineeringblog.com/the-von-karman-vortex-street-and-tacoma-narrows-disaster/</a>
Spiral ridges are added to chimneys to prevent the effect: https://web.archive.org/web/20190824084241/https://spartaengineering.com/vortex-shedding-and-tall-structures/</a>
And it happens also at wide scale, and can be seen from space:

https://earthsky.org/earth/these-are-von-karman-vortices</a></li>
https://earthobservatory.nasa.gov/images/90734/two-views-of-von-karman-vortices</a></li>
https://oceancolor.gsfc.nasa.gov/outreach/ocsciencefocus/VariousViewsofvonKarmanVortices_o.pdf</a></li> </ul>

Note: I first posted this article on: https://www.seabreeze.com.au/forums/Stand-Up-Paddle/SUP/The-definitive-solution-to-fins-and-foils-whistling-humming--The--Donaldson-trailing-edge-\</a> </blockquote>

Windsurfing, back to the roots

2008-10-05T00:00:00+00:00

I am an avid [[https://en.wikipedia.org/wiki/Windsurfing][windsurfer]], or maybe I was. The sport is now mature (I have started in ... 1975), and have somewhat lost the excitement we enjoyed before as the state of the art was constantly progressing, but have stagnated for some years now. It even kind of became an "old people sport", as the new generation - even my daughter - took on [[https://en.wikipedia.org/wiki/Kitesurfing][kiteboarding instead]] which is easier to learn and less physically taxing, especially when you must carry all the gear on soft sand.
But the excitement is back, in the form of a... return to the roots! First a lot of people began to put a windurfer rig on top of a surfboard, specifically the new large [[https://en.wikipedia.org/wiki/Stand_up_paddle_surfing][SUP]] boards, able to support more weight than regular surfboards, not unlike [[https://www.surfline.com/surfaz/surfaz.cfm?id=924][tandem]] boards. It is really a return to the roots, as the first windsurfer was conceived exactly in this manner (putting a rig on a longboard). However, this time, thanks to the progress both in windsurfing technique, sails, rigs and fins, and board construction and shape, the result has nothing in common with the early sailboards. Even Robby Naish, our God of windsurfers has [[https://www.shq.com.au/shq/ktml2/images/uploads/SUP/DW_img003.jpg?0.44054415931884455][tried it]] too.
Then,what happened to surfing has been happening also to this "new old" surfing-with-a-sail reinvention of sailboarding. First, we saw the "hotdogging" movement I witnessed in my surfing youth with wide and shorter boards, with a fin placed full forward and a step to release the water flow at the tail. For surfing it was the famous 1970 [[https://www.newyorksurf.com/modules/xcgal/albums/userpics/10359/normal_small%20aipa.jpg][stingers]] of Ben Aipa, for windsurfing the [[https://www.kona-windsurfing.com/products/konaminitanker.asp][Kona]] with a step bottom, and modern windsurfing traits that are the pad and straps.
And now, we are entering surfing's 1960s and its the twin finned short [[https://www.surfline.com/surfaz/surfaz.cfm?id=803][fish]], with the new AHD [[https://www.a-h-d.com/news/index.wrd?newsid=340&ahdid=3ea1a823d8d614e09fdb88978d143f45][Sea lion]], a strapless twin fin, and even some custom boards like the one in the picture
We are even seeing the return of soft cloth (aka Dacron) sails, in the form of the new [[https://www.hotsailsmaui.com/2008/sails.php?sail=superfreak][superfreak]]. Although I must confess that I am not ready to move back from my beloved [[https://www.ezzy.com/][Ezzy sails]].
So, I am back on a windsurfer after 33 years, with my new Kona and Sea Lion, ready for new adventures... see you on the water!

Update 2008-10-20 🔗</a></h2>
See some nice descriptions and photos (french) of a trial day of the sea lion at the [[https://www.u-ride.net/modules.php?name=Forums&file=viewtopic&t=8704&postdays=0&postorder=asc&start=0&sid=ea02b09eff3dbe58ebe5be8215198871][U-ride forum]], and videos of this week-end ( [[https://fr.youtube.com/watch?v=Bt_V1V4Zqa0][video1]], [[https://fr.youtube.com/watch?v=E7V0hzMvBi4][video2]], [[https://fr.youtube.com/watch?v=TEySjxNs9Uo][video3]] ).