Dolosse – a South African invention used over the world
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Dolosse – a South African invention used over the world
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Re: Dolosse – a South African invention used over the world
#2[deleted]
Re: Dolosse – a South African invention used over the world
#3Interesting. Been to South Africa a bunch but never clocked that they were different from the more common antecedent, the tetrapod[1].
Re: Dolosse – a South African invention used over the world
#4In Germany (on the island Sylt) they recently removed all of these structures again after decades of them being a staple on Sylt's beaches. They were found to have no positive effect on protecting their shores.
I'm having a hard time to find a good source to quote but look for: "sylt tetrapoden" if you want to dive deeper.
Re: Dolosse – a South African invention used over the world
#5In Germany (on the island Sylt) they recently removed all of these structures again after decades of them being a staple on Sylt's beaches. They were found to have no positive effect on protecting their shores. I'm having a hard time to find a good source to quote but look for: "sylt tetrapoden" if you want to dive deeper.
Ok I stand corrected these are NOT tetrapods. Sorry for the confusion
Re: Dolosse – a South African invention used over the world
#6In Germany (on the island Sylt) they recently removed all of these structures again after decades of them being a staple on Sylt's beaches. They were found to have no positive effect on protecting their shores. I'm having a hard time to find a good source to quote but look for: "sylt tetrapoden" if you want to dive deeper.
Ok I stand corrected these are NOT tetrapods. Sorry for the confusion
Well, confusingly, the last picture on the blogpost look (to my untrained eye) to be tetrapods. Those are 'tetrahedral' (ish) shapes.
In contrast, the https://en.wikipedia.org/wiki/Dolos (plural 'Dolosse') are two tapering cylinders at right angles to each other. They have the same symmetry, but a different structure. Does that make any difference to how effective they are? No idea!
edit: When I said the "same symmetry" of course I should have said the dolos has some of the symmetries of the tetrapod (subgroup?).
Re: Dolosse – a South African invention used over the world
#7Interestingly the author shows a photo of a spot in Cape Town where there are two distinct structures in use - close up, in the photo, are actually Tetrapods - as pointed out in other comments, these are an earlier invention from France and also used quite extensively throughout many parts of the world (including... right here where the Dolosse were invented).
Further down that jetty are structures with the actual Dolos geometry. It would be interesting to know if, specifically, those geometries were chosen specifically to be placed in those two parts of the wall as they are for specific properties, or if came down to having certain quantities made on hand and their distributions matched the shape of the wall required, or what.
You can see what I mean, this distinction in the exact location where that photo is taken on google maps, here:
https://maps.app.goo.gl/Vn3tGhM81oMqPVpm9
-33.899126, 18.412751 Mouille Point, Cape Town, 8005, South Africa
Re: Dolosse – a South African invention used over the world
#8Save yourself the blogspam, go directly to https://en.wikipedia.org/wiki/Wave-dissipating_concrete_bloc... and enjoy the whole collection !
Re: Dolosse – a South African invention used over the world
#9Save yourself the blogspam, go directly to https://en.wikipedia.org/wiki/Wave-dissipating_concrete_bloc... and enjoy the whole collection !
A bit rude, this doesn't come across as spam but a genuine human sharing something interesting they came across. Peak old internet (2000s) content. The wiki article is very short and doesn't actually have more or better pictures.
Re: Dolosse – a South African invention used over the world
#10Interestingly the author shows a photo of a spot in Cape Town where there are two distinct structures in use - close up, in the photo, are actually Tetrapods - as pointed out in other comments, these are an earlier invention from France and also used quite extensively throughout many parts of the world (including... right here where the Dolosse were invented). Further down that jetty are structures with the actual Do…
Mathematically, I think they both may be tetrahedons. The Tetrapod models it by 4 lines connecting each of its vertices to its center, the Dolosse by two opposite edges connected by a line through the middle.
I’m saying “may be” because it is possible that the center “arm” of the Dolosse is too large to make a true tetrahedon. That’s a degree of freedom in the design.
> It would be interesting to know if, specifically, those geometries were chosen specifically to be placed in those two parts of the wall
My guess would be that Dolosses interlock better than Tetrapods, allowing for steeper inclines on stacks of them.