Dolosse – a South African invention used over the world • Hacker News Board

Re: Dolosse – a South African invention used over the world

#41

Post by nephihaha » Tue, Jul 07, 2026, 8:17 PM UTC

PaulDavisThe1st wrote: post #30

nephihaha wrote: post #24

Earlier quoted context omitted.

Some people here think if it's on Wikipedia it's authoritative. Yours truly has written many Wikipedia articles, some translated into ten or more languages. I've seen how ugly it is behind the scenes there. I miss blogs. They are omitted from searches now but are among the best internet search content. Threadinburgh is one of the best online resources about Edinburgh by far.

> They are omitted from searches now but are among the best internet search content I use google search with &udm=14 to remove all AI elements in the results presentation. Searching for "dolosse", the HN item is the 3rd link, and TFA is the 4th. They are preceded by Wikipedia, and a dolosse-manufacturer's page. Not sure why you think "blogs are omitted from searches now".

Maybe because I do searches for specific topics and no blogs appear in the results. This is even though I know certain blogs contain information on the topics I'm interested in, and instead I get "trusted media" which has information often only loosely connected to what I'm after.

Re: Dolosse – a South African invention used over the world

#42

Post by nusq » Tue, Jul 07, 2026, 10:36 PM UTC

silves89 wrote: post #39

nusq wrote: post #15

Finnally something I have knowledge of. Dolosse were invent in South Africa many years ago, but they are only one type of concrete block for wave dissipation and protection. Many others exist and some of them are patented and require the payment of royalties to be used. Anyway, in Portugal we do not use dolosse ever. We used it once in Sines deepwater breakwater, which suffered a catastrophic collapse in 1979. The pr…

Thanks for this background! I encountered dolosse or something dolosse-like at Praia da Ilha de Tavira, in the Algarve, here: https://www.google.com/maps/place/Farol+de+Tavira+Molhe+Oest...

Those are tetrapods. In Portugal we only use tetrapods, Antifer blocks and rock slabs if avaiable with the right size and density. The weight of the blocks is a function of the design wave height and period, so we have blocks with different sizes but not shapes. Sometimes we use blocks with high density concrete, cause higher density works both ways, it inscreases weight and reduces volume. You can see this in Sines, the blocks change colour on the tip of the breakwater, because the concrete has a higher iron content. https://www.google.com/maps/place/37%C2%B056'28.2%22N+8%C2%B...

There is one exception. In the Azores, there are core-locs because the breakwater was designed by the US Military. https://www.google.com/maps/place/38%C2%B043'36.6%22N+27%C2%...

Re: Dolosse – a South African invention used over the world

#43

Post by bix6 » Wed, Jul 08, 2026, 5:14 PM UTC

RetroTechie wrote: post #40

bix6 wrote: post #29

These are cool shaped but they don’t actually work; coastal armoring in general does not work as it does not prevent erosion. Sand replenishment is increasingly the path taken. Australia has an amazing pumping system (a jetty blocked longshore sand transport so they pump it around to the other side). We could just stop building so close to shore…

> coastal armoring in general does not work as it does not prevent erosion. Not that simple. Example: east of Lauwersoog (north shore of the Netherlands) there's a dyke reinforcement project underway. Roughly 2/3 of the dyke's seaside is covered with regular rows of interlocking concrete blocks (~25 x 25 cm top view). At the base of the dyke, there's stone rubble to dissipate wave energy. These are heavy stones: 100s…

Sorry I was unclear. By erosion I meant beach erosion. I do agree that armoring can help preserve a structure like a dyke. The issue is the sand as you mention with the sand engine.

In my neck of the woods armoring is falling out of favor as sand replenishment takes over as the primary strategy.