24 Sep 2021

Your questions answered: the German diving bell vessel

In focus: ✔ A new diving bell ship for FMSW Koblenz

Ben Littler

We’ve recently been busy with the construction of a new diving bell ship for FMSW Koblenz and operator WSA Rhine. The new vessel, named Archimedes, will operate mainly on the rivers Rhine and Mosel in Germany.

This is a vessel unique in the world. A diving bell ship is required on the German river network due to the rapid currents experience there, which render diving both impractical and dangerous.

Archimedes will replace the iconic Carl Straat, which has performed her duties admirably since 1963. The replacement vessel draws significantly on the proven design of her predecessor, adding components suited to a safe, modern operation.

The project has received quite a lot of attention, with a number of people contacting us with questions about the vessel. Here, our project managers, Marius van Wijngaarden and Stephan Bekkers answer your questions on Archimedes.

Q. How far down will it go? It could look for things in Bermuda Triangle and Hawaii for lost planes and ships in the harbour?

Archimedes can operate at depths of up to 10 metres. This is sufficient for the locations she will be working in. Most of the time, she will operate at between 4 and 7 metres.

It is possible to use this technology at greater depths, but it would involve using longer tubes and increasing the pressure – you need 0.1 bar additional pressure for every extra metre of draught. So, yes, you could use such a vessel to look for the Bermuda Triangle, but you would need a slight modification.

Q. Cool, but what 4?

Archimedes is a real multi-tasker. She will perform multiple tasks. These will include maintenance works, inspections on lock doors and buoy anchor points, cargo retrieval, bottom sampling, obstacle removal – even the removal of unexploded ordnance from the Second World War.

Q. Oh Archimedes endlich fertig darf die Carl Straat endlich in Rente gehen? (oh, Archimedes is finally finished, the Carl Straat can finally retire?)?

For the first few months of Archimedes’ operation, the Carl Straat will continue to serve as a backup vessel. But her retirement is close by now, yes. As far as we know, it has not been decided what awaits her for the future.

Q. Awesome bit of kit, how does the water no flood into the bell?

The vessel does not flood due to the overpressure in the diving bell. To ensure safety we have included backup. A single compressor is more than enough to present flooding at the depths the Archimedes will work at, but we also have a second compressor in place.

It’s the same for all onboard systems – the fire-fighting system, for example – Everything on board is 100% redundant.

Q. Do they have to do surface decompression?

Working at depths of up to 10 metres, no surface decompression is required. There is a pressure chamber, however, where the crew will wait until the pressure is equalised to that in the diving bell.

On return to the surface, the process is conducted again in reverse.

Q. What level of pressure does the interior have to be able to keep out the water at the bottom?

For every metre of draught, 0.1 bar pressure is required. So working at a maximum depth of 10 metres, Archimedes requires 1 bar of pressure.

Q. How many engineers on board and what licence will they require?

Typically there will be a crew of seven on board. This will consist of a captain, diving master, cook, dedicated engineer, someone with responsibility for the dive crew and operation, first skipper and chief engineer.

All onboard are required to have a certificate for working in a pressurised environment – the G31 statement. This must be renewed annually.

Q. Can I take it nome for some gold dredging?

With all the tools featured in the heated diving bell, this would be the perfect vessel for some gold dredging. Unfortunately, Archimedes is going to be very busy in Germany, where she will have her work cut out working every day on the rivers. She just doesn’t have time for gold dredging right now.

Maybe you could have a word with our clients, we hear they may have a second-hand vessel for sale in the coming months.

Ben Littler
Pontoons and Barges
Dredging and Dredging Equipment