A week ago already, Frauke and I went on an evening walk in Kiel Holtenau. Beautiful wave watching to be done there as always! Here you see the one side of a ship’s V-shaped wake approaching our vantage point. You can see the individual “feathers” of the wake: Short wave crests, all parallel to each other, but slightly shifted to the side to form a straight line (well, two straight lines to form a V with the ship at its tip, but the other side of the V is not visible on this picture).
And this is what it looks like when the wake has moved past us: Looking on the back of the feathery shapes. The ship that made all these waves has long sailed away.
Last weekend, while wave watching at one of my favourite spots, I observed something curious.
Look at the movie below, this is what the turbulent wake of a ship usually looks like right behind the ship: As the ship moves forward through the water, it displaces water and right behind it, it creates a hole that has to be filled in again by water from behind the ship and from the sides. So right behind a ship, water is sucked towards the ship. So far, so good.
But now look, there is a ship coming out of the locks at Kiel Holtenau.
What that means is that it is pretty much coming out of a dead end, since, in order to keep the water level inside the Kiel canal stable, the lock closes it off from Kiel fjord at all times by either set of doors.
The wake of the ship looks pretty normal so far:
But any ship displaces a huge amount of water. The one above is 115m long, 19m wide and has a drought of 5.4m (according to my favourite app). That means that it displaces almost 12000m3 of water! And this water has to come from somewhere (otherwise the ship would leave a trench in the water where it went, much like your hand leaves a trench when you pull it through sand at the beach).
But since the ship is coming out of a dead end, there is only so much water that can fill in said trench from behind and the sides. So even after the ship has sailed, there is still water moving back into the narrow entrance of the locks!
See below: (Surface) water on either side of the wake is moving to the right, driven by the wind. But in the wake itself, water is moving left, still filling in what was sucked out of the entrance of the lock! And that for quite some time after the ship is gone. At the end of the movie below, the camera turns and you can see the (white-and-green) ship sailing away just to give you an idea of how long this is after it left the locks…
Isn’t that cool?
P.S.: Yes, I though about whether there might have been water pumped out of the end of the dead end to fill up the lock chamber again, but I don’t think that’s it. Do you?
I’m lucky to have great friends like Alice, who was spontaneous enough to go on a mini cruise with me today (for which I was only given tickets when I was already on my way to meet her somewhere else). So we boarded the historic MS Stadt Kiel and the adventure began! (Note the Europe flag? Hope you’ve been voting already when you are reading this, otherwise stop reading and go vote! :-))
I had never been on the MS Stadt Kiel before, even though I’ve seen it many times. It’s lovely inside — historic charm and the smell of marine diesel. What more could you want on a gloomy grey Sunday? And a super nice crew of volunteers who run the ship!
Plus we got to see all my favourite spots, like the light house at Holtenau. You also see the pilot station right behind the light house, that’s where the pretty orange pilot ship lives that you see at least in every other of my blogposts ;-)
And the Kiel Canal locks at Kiel Holtenau; looking at them from Kiel fjord. I usually take my pictures either from the shore on the left close to where you see the tower, or from the bridge that you see in the background.
And then, as you do on historic cruises, there was Swing dancing with a dance crew who was performing for us and then even gave us the opportunity to join in, which, of course, Alice and I did. Unfortunately I wasn’t wearing exactly historical costumes, but hey! It was fun! Thanks, Christian! :-)
For privacy reasons as well as for fairness, I had to give everybody the same face that I am making on the picture ;-)
Now that the weather is nice and sunny again, here is what it looked like only last Saturday. It wasn’t even really stormy, but windy enough so that the ships leaving the locks at Kiel Holtenau were working a lot harder than usual. Especially difficult when you are almost empty and then there is a lot of wind! See that wake?
Right behind the ship you see above, there was a second ship leaving the locks. See how milky the water looks where the first ship went from all the air bubbles that were pushed under water by the ship’s propeller? You can even see some of that water spreading underneath that floating barrier in the foreground!
And see the difference between the waves on the upwind side of the ship and the downwind side?
Here is the picture that my friend sent me that she took from inside of the café that we were sitting in before I HAD to go outside and take pictures. If I am being sent pictures of my back every week by my friends, are they trying to tell me something? :-D
On Sunday, I set out to see a large cruise liner go through the locks at Kiel Holtenau.
What happened, though, was that a ship with a smiley painted on its deck came first. Do you see the two shadows to the right of the ship, the left one aligning with the one side of the wake’s V? That’s the pillars the bridge is resting on.
This ship has a very interesting wake, since it consists of several Vs. Not quite sure why. Also, it seems to be driving in a very non-straight line, judging by its turbulent wake.
But watch what happens when the wake hits the sides of the canal.
The green thingy interrupts the straight line of the shore and creates these beautiful ring waves!
A little while later they have spread half way across the channel, while on the other side, the wake is just reflected on the shore.
It looks funny how the reflections are so asymmetrical relative to the ship, but of course the ship isn’t driving in the middle of the channel, so they have to be.
And on the other side of Kiel fjord? Yep, the cruise liner speeding past the locks. Clearly they decided to not take the shortcut through Kiel canal.
And now the small ferry is starting to cross. And in the background: The cruise liner!
I realize the earlier pictures in this posts were a lot nicer than these, but look how funny: Above you see the small ferry going around the larger ship, and the wake tracking where it went on its turn. And below, it has turned into a V! Waves are funny.
Yes, we are back to wake watching! Today I went to a new-to-me wave watching spot: The bridge across Kiel canal close to the Holtenau locks, which you see in the background of the picture below. And I should have checked out my favourite ship tracking app for better timing, I had to wait for quite some time before there were any ships apart from the small ferry which you see crossing right at the locks! But the wait was well worth it in the end!
In these pictures, you see very clearly the different parts of the wake. The turbulent wake right behind the ship where the ship has displaced a large volume of water and where the ship’s propeller has induced a lot of turbulence. The turbulent wake is bound by the foam created by the breaking bow waves. And outside of all of this, the V of the feathery wake opens up with the ship at its tip.
I am super excited about these pictures. Do you see the wake reflecting on the right (south) side of the Kiel canal?
And while it was pretty easy to interpret the pictures above, and the one below is still fair game because the turbulent wake of the third ship is still clearly visible, even though the ship is not, it is getting more and more complicated, isn’t it?
But now, with two of the three ships gone, it has suddenly gotten a lot more complicated. And it doesn’t help that the sides of the canal aren’t completely straight which leads to the mess in the lower right corner…
This is definitely a new favourite wave watching spot which you might see more of in the future! This stuff makes me so happy :-)
Beautiful morning arriving back in Kiel… Looking downwind, the weather might seem pleasant (especially when focussing on the sunrise).
But looking upwind however, the wind rows on the water as well as the white caps on the waves indicate that it’s quite windy!
Very cool: the turbulent wake of a ship interrupts the wave field and therefore, with its different surface roughness, is clearly visible!
And below you see so many things: The sand bank running from the lighthouse towards the next headland becomes visible as waves are breaking on it. The turbulent wake of that blue ship we saw above already is still clearly visible, as is its V-shaped wake. And you see our own wake as the feathery pattern that runs all the way from the bottom edge of the picture to way behind the blue ship!
And here our own wake becomes even more prominent as we turn. Laboe in the background…
Here is another ship, waiting to enter the locks of the Kiel canal. It’s moving only very slowly (so hardly any wake visible), but you see how it’s sheltering the water from the wind so the downwind water appears completely smooth right at the ship!
And here are some more wakes and sheltered spots of water surfaces. Locks of the Kiel canal in the background!
And another look at the locks. Do you notice how the wind rows still indicate that it’s quite windy, but how it’s a lot less windy than it was further out?
And then we are in the Kiel fjord. This is the upwind shore — see how waves are only slowly forming and building up with longer and longer fetch?
And then in the sheltered port a different kind of waves: Our bow propellers mixing the inner Kiel fjord!