By Alan Bliault
Thoughts about news and sharing
Since my dear friend Brian Russell died, we have hit a pause in communication in The Hovercraft Society. The world continues though, and that does include ACV and SES technology and operations. I have recently made a visit to two SES specialists in Southern Norway who have closer connections to IoW than I expected (see below). I am preparing material for the Royal Institution of Naval Architects that will take a while. Meanwhile it strikes me that it might be good to share some thoughts with you and so try to regain a bit of contact.
I have just today (October 21st 2020) found that THS now has a functioning Internet Site. This is really good news! Once it has been matured a bit it should offer us Hovercraft enthusiasts and professionals a means of sharing news, technical data and papers, and operational experience perhaps.
To encourage members and perhaps even visitors to the site I offer some thoughts. If others show interest there are technology advances currently ongoing for amphibious ACV’s, SES, Air Cavity Craft, intelligent control systems and both hybrid and fully electric propulsion systems. It would be wonderful to encourage the current generation of engineers to drive this forward! Air Cushion Technology has a real place in the energy transition I believe.
So, to some random updates for visitors to THS site. They are my thoughts and interpretation. I am not commercially linked, just interested now since I am one of the 1970’s generation. I am biased towards air cushion technology though!
Random Updates October 2020
In these days of the internet, I am going to assume everybody has access and so can click on a link. The fact you are probably reading this on the THS site likely proves that. I will give below links as direct as I can to material, as often sites are not easy to navigate from the top. Links are at the bottom of this note.
While you might not consider it quite air cushion technology, air lubrication for shipping has become an important business in the last few years. There are several players in the specialist market who then deliver designs or installation packages to shipyards. One such is Silverstream in London. They are doing quite well with contracts in China for the moment. Their system is based on bubble stream rather than air/vapour sheet that Samsung and Mitsubishi both employ. It is efficient and a step in the direction of reducing power, emissions etc.
Some THS members may know that I have finally managed to finish my textbook on air lubrication and air cavity ships earlier this year in collaboration with specialists from Russia and China. The lubrication side is focussed on large and relatively slow vessels, typically 15 to 22 knots for cruise liners for example, or 10 to 18 knots for inland transport barges. Air Cavity vessels on the other hand are aimed at fast ferry speeds in the range 25 to 35 knots. Work on the concept started in Russia back in the 1960’s and continues there. Their ideas are based on having a forward planing surface, a cavity surrounded by slim side ‘skegs’ and an aft closure to the cavity that is another planing surface normally partly wetted.
This concept (think of the very early US captured air bubble concepts in the same time period) does work well to reduce drag, improve ride somewhat compared to a simple planing craft, and so kind of fitted with fast transport on the major Russian waterways, in competition with their hydrofoils. In the last couple of decades, the major application in Russia has been for fast landing craft. A number are in service with their navy.
Since the early 2000’s an engineer here in Norway has worked on a development of the air cavity principle aimed at improving efficiency for ferries without the complications of SES skirts. Several R&D programmes later, investigation of both catamaran and single hull geometries, and a prototype built in Turkey, the concept was accepted by the EU for development funding. The idea was to use the reduced powering requirement to enable a fully electric fast ferry. Back in 2014 when the work started in earnest this was quite early days for such a concept, so some big challenges to overcome.
It is interesting to note that in that process, Effect Ships International developed a cavity geometry that has no forward planing surface, and uses a hinged, sprung and damped rear cavity closure. The proportion of displacement supported on the cushion was above 70% (Russian craft typically have 60% or more supported by planing lift rather than the cushion), and the rear hinged ramp is designed to run ‘dry’. Following many trials and tribulations, a fully electric ferry called ‘BBGreen’ was completed and put in trial service in Stockholm in 2018. It met its target for the EU R&D programme, but technology was already advancing and so Stockholm and other places are looking for vessels like BBGreen but with longer range etc. Effect Systems International has passed to new owners in 2020 and SESX Marine Technologies are now working on that with Green City Ferries.
I guess that some of you may be following ‘transition’ technology developments just now with interest. I am amazed at the speed of development. The successor to BBGreen or its utility cousin (see Tuco link below) will indeed have much improved range on batteries, enhancements to ride control, and in the near future perhaps hybrid battery and fuel cell powering. I can almost hear you saying it – the catamarans will be doing the same – well yes of course – and by the way, Thames Link are currently participating in an EU funded R&D programme looking specifically at hybrid and fuel cell ferries.
Moving on to deep cushion SES, here in Norway there is UMOE in Mandal, and a relatively new Naval Architecture company in Kristiansand called ESNA working with these craft.
UMOE designed and built the Minehunter SES, and latterly the Fast Strike SES for the Royal Norwegian Navy. Here and there I see the vessels in Stavanger. Just now the strike craft have been surveyed for a refurbish and upgrade programme for the RNN. They remain the fastest naval vessels in the world, and the military outfit gives them an amazing capability for such a small vessel.
Being a supplier to the military for any country is a whole different ballgame to commercial vessels, but once that experience is there, it allows access to a special market. In UMOE case they worked with Textron on the transformable craft development in the early 2000’s, and then on the LCAC replacement programme, supplying the first 13 ship sets of fan volutes, propulsion ducts and other items. Unfortunately the Trump policy got in the way of continued deliveries. Most unfortunate as UMOE are really specialist and high quality in this area, after many years of experience, and had a good relationship with Textron. Fortunately their specialist CFRP experience is now being used to supply a number of components to the UK Type 26 frigate programme.
On the commercial side UMOE are now working hard with their Wavecraft SES for offshore supply and wind farm service markets. It is quite early days yet as most offshore wind farms are quite close to shore in shallow waters so far, but once Dogger Bank gets going fully, and the various deeper water farms get built there should be quite a market opening up.
The big development with the SES recently has been using instrumentation and software to monitor cushion pressure and modulate the airflow dynamically. While at speed this gives a much smoother ride, and when the vessel is docked up to a wind turbine on cushion it can stabilise the bow deck so mechanics can board the turbine safely in up to 2.5m seas. So mechanics can arrive not feeling queasy, and the maintenance planners have a bigger weather envelope to work with. Quite an achievement.
UMOE now have the offshore O&G industry also in their sights, since the above capability plus a long range compared to helicopters begins to make them a practical cost saving and HSE improving option for many existing facilities.
Moving on to ESNA, they first developed a small SES which they call a ‘daughter’ craft for Wind Farm construction support. The vessel is deployed from a large construction vessel stationed at the field being constructed for fast in-field transfers to the group of turbines. Trials with Vattenfall and Ørsted were carried out in 2018 successfully. The ESNA SES ‘Sea Puffin’ has their own cushion control system aimed at improved ride, and controlling motions when docked to a turbine.
Success with the ‘Sea Puffin’ lead ESNA to developing a larger design for personnel transfer from shore. This design incorporates a hybrid drive so that while in the field docking and position keeping is powered by battery, transit is powered by diesel electric propulsion. A wind farm service company CWind has contracted the first vessel to Ørsted for the Borssele 1 and 2 wind farms 26 km from the coast in Holland.
The vessel is currently in late construction stage at Wight Shipyard in Cowes. So SES technology comes back to ‘BHC’! Do keep tabs on the IoW press for the launch.
ESNA are now working on a new fuel cell powered concept, where instead of diesels, it is fuel cells that can top up the batteries out at site. Like all the other companies working on fuel cell marine concepts a key issue is the hydrogen tankage and location.
A thought is that if at least the fuel cell concept can replace diesel power for the ‘near shore’ farms, that will at least improve green credentials. For the farther offshore and floating farms there needs to be a transition to hybrid power as a first step.
Linking back to ferries, there is much going on here in Norway around both battery and fuel cell ferries, large and small. In addition there are markets such as the utility craft for fish farms that are candidates for electrified craft such as an SESX vessel supplied though Tuco. It is all about cost savings combined with environmental improvement.
Links
Silverstream: https://www.silverstream-tech.com/
BBgreen: https://www.bbgreen.eu
Green City Ferries: https://www.greencityferries.com/
SESX https://www.sesxmarinetechnologies.com/
Tuco: https://prozero.dk/prozero-17m-asv/
UMOE: https://www.um.no/
ESNA: https://www.esna.no/
Wind Partner: http://windpartner.no/
CWind: https://cwind.global/engineering-the-next-steps-on-the-path-to-zero-emissions-ctvs/
Closing Out
If you like this, do let Mike Mooney know and we can find a way to connect us all closer together via the internet site. There is lots I would like to hear from others of you out there, particularly the operations side of things!
The Covid pandemic has shown that Zoom or Microsoft teams based seminars can include people as far apart at Australia, Canada, Norway and UK. They are not so difficult once one has the technical presentations committed. Chat sessions can also be set up perhaps. All this without moving from your own location! Maybe I am dreaming a bit, but I live in hope.
With Kind Regards,
Alan Bliault, FRINA
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