Tag Archives: bow waves

Wave watching on Kiel Canal: Bulbous bows and how they shape the wave field

Even when I fully intend to just go for a Saturday afternoon walk to catch up with a friend, this is what happens…

I get distracted by waves. Like the crisscrossing pattern of waves and their reflections that you see below.

Or the amazing bow waves of ships passing by. Isn’t it fascinating what a huge amount of water is displaced by the ship’s bulbous bow, piling up into a mountain in front of it, then the sharp dip where the actual ship begins? (If you want to read about why ships are built with a bulbous bow, check out this old blogpost).

Having a bulbous bow alone does not always lead to the same bow wave. Which is fairly obvious when you think about it, of course the speed of the ship or the shape of the bow influence the wave field that is created, but also how heavily the ship is loaded, i.e. how deep the bow is in the water.

What you can see very nicely on the sequence of pictures of bows and bow waves in this post are bulbous bows going from fairly far out of the water (above) to fully submerged (towards the end).

And I just love the sharp contrast of the smooth water piling up and then the turbulence and breaking waves right there. Interesting example of subcritical and supercritical speeds, btw: The ship travels faster than the bow wave (so the bow wave can’t overtake the ship, but always stays behind it, forming a two-dimensional Mach cone).

The ship in the picture below is the odd one out in this blogpost: It does not have a bulbous bow but just pushes water in front of it. This is an interesting example of a bow shape that is clearly not optimized for energy efficiency when traveling large distances, but then the purpose of that ship is obviously a different one. But isn’t it amazing how such a small ship creates waves larger than all the other much bigger ships do, just because they have better bow shapes?

But beautiful wakes nonetheless. I love those tiny ripples riding on top of the wakes!

And, of course, the checkerboard pattern of a wave field and its reflection.

Here is another example of a ship with a bulbous bow, this time it is almost submerged. Since they are designed to be fully submerged, this ship is loaded in a way that is closer to what it was made for, and you see that the generated waves are smaller than the ones in the pictures up top.

And look at its wake — really not a lot going on here, especially when compared to the much smaller ship a couple of pictures higher up in this post!

Now for a ship that is hardly creating any waves at all, the mountain of water that it’s pushing in front of its bow looks especially weird since the bulbous bow isn’t visible any more.

See? (And isn’t it cool how the chronological order of pictures in this post just coincided with ships laying deeper and deeper in the water? I love it when stuff like that happens :-D)

And then, of course, I had to include some more pictures of beautiful wakes…

Do you see, comparing the picture above and below, how the first one was taken when the wake had just reached the shore, and the second one the wake was reflected on the shoreline already?

Not many things make me as happy as wave watching :-)

P.S.: Ok, one last bonus picture (non-chronological, we saw it some time during the walk. But that’s ok, I wasn’t going to include it until the post was already done and I decided that you just HAD to see this): Someone who is clearly not using their bulbous bow to their advantage. But at least I get to show you what they look like when they are not in the water. And we got to speculate about how annoying it is to be on a ship with such a strong tilt all day :-D

Feathery wavelets and wakes

My sister took this amazing picture — and from a train no less! And I got super excited. Can you see the feathery wavelets* of the bow wave of that large ship? And then the wakes of both ships, spreading out at the same angle? I should definitely start spending time on high bridges going across canals, there is so much unused potential for wave photography!

*I was super convinced at first that they were called “winged wavelets”. But then doubt started to kick in, so I asked google. Turns out they are called “feathery”. However, apparently “winged wavelets” is a very poetical expression, all google hits are in some poem or other! And one that I really liked by Mary Bamburg, where it goes like this (as part of a longer poem):

“… waves wring sand from the shore,
strew shells, strech after them
white wash and wild winged wavelets
glass green, blaze blue, slick silver …”

Does it create the same beautiful image before your inner eye as it does for me?

Wavelets on bow wave

The other day (well, the other day when I was still at sea and wrote that blog post. Been quite a while since…), when sailing in calm waters, I noticed the wavelets of a bow wave.

And I cannot not see them these days! No matter how much the other waves try to disguise any trace the boat might be trying to leave to prove its existence, the bow wave wavelets put up a fight to be noticed.

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Below, you see the direction the ship is sailing in (yellow), the wash from the broken bow waves (green) and the wavelets that form the bow wave (red).

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And they look extremely pretty in the setting sun, too!

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If you like pictures like this, you’ll love my book! Stay tuned!