Soviet Era Hydrofoil Pictures

The only reason why the Boeing Jetfoil is running in HK is speed, no other reason. It is cheaper to run than a convention multihull doing 45knots. Yet it is passenger limited which is why conventional cats have made serious inroads in the HK market.

Jet foils can't take 450pass in one pop! Conventional cats can.

Seakeeping has nothing to do with being a criterion in HK. The waters are generally benign 1m waves nominally. The only times the waters get rough is during a typhoon.

 

The jetfoils are all being run at 40 knots - the same speed as the Tricats and Austals in operation there as it makes sense for scheduling. There is no speed advantage.

Seakeeping has a lot to do with the criterion in HK. If you spend some time on those ferries you will observe the number of passengers who get seasick in the "benign" conditions. Also I suggest you go and speak with Turbojet and ask them directly why they keep their jetfoils running.

The largest ferry operator in Hong Kong even went as far as to develop their own Jetfoil in China at great cost when they could no longer get new ones from Boeing. Agreed the jetfoil can't carry 450 passengers but they remain the undisputed benchmark for passenger comfort.

Right now there are too many ferries in HK and many have been laid up. Guess what: it is the catamarans rotting at anchor and not the Jetfoils.

 

Clearly you haven’t designed many fast passenger ferries for the HK market. Having being involved with fast ferries for over 20 years with many clients in the HK waters, and at different companies, never once has seakeeping come up. Speed, speed and yup, you’ve guessed it, speed. Fast as possible from HK to the casino…that’s all they care about. It became a speed war between companies operating the routes. That’s why GT eventually took hold, to eeek out that extra knot or two. No expense spared. But that was of course before fuel prices rose to the heights they are today.

The raison d’être of the Tricats, was to beat the Jetfoil into Macau. That was the SOR.

I recall one meeting with one of the largest if not the largest operator of ferries in HK waters many years ago. He wanted a T-foil ride control system on board. We asked why..he said “marketing”. He even said…I know it is not required, but I makes for good marketing, if we have ride control system the others don’t (well didn't back then). Ergo it sells bums on seats.

Having travelled many times between HK and Macau I have observed the same reaction by the passengers. On a flat clam day, one albeit it large amplitude wave passes by, generally from another vessel running near by the approach to Macau harbour and many hands went up and excess vomiting occurring. Just one solitary wave. Chinese are not good sea farers.

The whole seakeeping aspect is a myth and just pure marketing which many seem to have bought into, for the HK market.

Perhaps if they went to Kawasaki, they bought the rights from Boeing many years ago. The hardware for most of the critical items no longer exists, simply because it is no longer cost effective to produce such expensive bits of equipment for a very small number of vessels. Simple economies of scale. KHI are simply not interested.

High fuel prices, to run those fast babies coupled, with price cuts from competitors has not been good for HK operators of fast ferries. Coupled with the new bridge system will lay up even more vessels. As noted above, the jetfoil does not take as many as 450 pass. But when a cat doing 40-45knots is running at low to at best half full, which do you think is cheaper to run…yup, the jetfoil. It is simple economics.

Only the airport route is doing well. But even then…for how much longer?

 

Two restored Russian hydrofoil ferry's (model Voskhod) are in use in Amsterdam. They're called "the fast flying ferry".

http://www.noordhollandsdagblad.nl/incoming/article6752131.ece/ALTERNATES/w470/fastferry.jpg

It's an interesting felling to "take off", but after that you don't experience much of the speed.

Cheers Hans

 

Your single design project in HK is clearly from the previous century when there was a boom in ferry industry and two dominant ferry operators in HK thought about nothing but going faster with little regard for the economics of speed or comfort. Nowadays things are bit different with many more operators and far more routes all competing with each other.

There are far cheaper small ferries readily able to operate the HK Macau route than running a 30 year old gas turbine powered hydrofoil which has custom made waterjets and require a specialised facility to service gas turbines.

On the one hand you say seakeeping is a myth and on the other you clearly and correctly point out that Chinese people suffer more than most from motion sickness? It is quite logical that passenger comfort/seakeeping is an important criterion in choice of a ferry and makes the Jetfoil attractive because it offers both good speed as well as passenger comfort.

Most people Ooperators and passengers alike) are actually rather unhappy with the comfort of the latest generation Austals operating the HK - Macau route. The vessels tend to cork screw just nicely at the 3-4s period which makes one nicely seasick. Replacement ferries will certainly have to address this issue of passenger comfort.

 

Hmmm…interesting.
For the record it is 7 different types at 3 different companies. With a cumulative total of 20 if memory serves. I assume from you statement you’re speaking from a position of having designed many fast ferries for the HK market in the 21st century?

In case you’re unaware, it is called an SOR. You design a boat to meet the clients SOR. Not one you would like but what the client who is paying you wants. If circumstances change then so does the SOR and you design to the new SOR. However having been recently approached by 2 different operators wanting vessels of 40knots plus and 400 pax, it appears nothing has changed. Speed, speed speed. Same old over again. Yet they don’t want to pay for the general running and maintenance. As Mike Jagger says “you can’t always get what you want”.

Unless fuel prices change, it is a bitter pill to swallow. But shall probably be all mute once the bridge is in place.

Having designed vessels and being involved in HK for many years, there is no myth. When you design a boat, you look at the wave charts, regardless what is in the SOR. As noted here:



The predominant wave height off Waglan Island is circa 1.0m. And can be seen that 1m waves account for roughly 70% of waves annually. It is no myth. A standarad 40m catamaran should be untroubled by such a wave height.

What people choose to believe is entirely their own making. But it is not supported by facts. If you have designed for such sea conditions, you would know this.

Don’t follow. Period of what, the waves or vessels?

 

I have done enough design work in HK to know what I am talking about and have enough active projects in the major cities of the Pearl river from multiple clients to be up to date on what is being discussed on the ground.

Really :?: :!: I better go and ask for a refund of 10 years of University fees as nobody taught me that!

As the designer, the correct methodology is to work with the client to establish the SOR and not just blindly accept that there is no passenger comfort requirement. For sure there is one but the difficulty is in how to define it realistically in a way that is measurable during trials. Even if one cannot define the requirement exactly, the client will have some expectation... One has to think broader than what is just on paper in the SOR for a successful project.

Personlly I dont think the bridge will change anything. People will still rather sit in a ferry that in a traffic jam and struggle with parking problems in Macau.

It is not a question of whether the catamaran can handle those wave heights. The important question to answer is if the passengers can handle the resulting motions in comfort (we already know it is a problem!). As far as an operator is concerned he will want to know that his new vessel is at least as comfortable if not more so than any of his competition. Anecdotal evidence seems to suggest Austal did not get this right and the Tricat is still the preferred catamaran in HK for passenger comfort. So hats-off to the FBM team on that one!

Austal might have a tough time selling another vessel in HK based on their current track record of bad motions (unfullfilled client expectations not in the SOR!) and some other problems... (also not in the SOR!)

Period of the vessel motions

 

A discussion about design issues is very different from actual designed and built vessels running the routes. Regardless which "century" they are in.

That is the job of the salesman, to find out what the client wants and is willing to pay for. It is not naval architecture. Anyone can sit down and have a cup of tea and a chat, and discuss matters of “importance”. What is discussed and what is paid for are two entirely separate matters. That’s why salesman try to sell and not design boats; unless they do both and it becomes a mess . A good naval architect does not make a good salesman. NAs are, or should be, too honest to ever get too much success. The client wants/needs massaging of their ego, not being told cold hard facts that are counter to their aspirations. Thus, nice cups of tea and discussions, until they sign a contract and agree a price. A skilled salesman is worth their weight in gold, but in no way does it suddenly make them a NA.

The SOR defines the objective of the vessel. However, the design of a vessel is greater than the sum of its individual parts. It is a holistic approach, ergo, whether seakeeping is a requirement or not, one must review the design in respect of such an attribute; to do otherwise is somewhat negligent.

Taking a holistic approach is not written into an SOR, but that is the role of the naval architect; to make the design greater than the sum of its individual parts. Which is why some “identical” boats have good reputations and others do not, despite being “identical” in length/speed/pax numbers etc. taking a holistic approach results in a better overall design.

If a wave of 1.0m with a wave length of around 120m (from the typical statistical wave data of HK), is approx 3 times greater than the length of the vessel. Travelling at 40knots has an encounter frequency of roughly 1.76 rads-1, or a period of 3.5 seconds. Thus even though 1m wave height is not much, this period is roughly coincident with the natural period of pitch/heave of typical passenger cats. But this also needs qualification in the sense of what are the accelerations at this period of encounter? Looking at a standard ISO motion sickness at this frequency to ensure the passengers won’t feel sick in a 2hour duration (not the type that are always sick) means having an acceleration less than 0.50m/s^2. So, under taking a series of ROAs to obtain said data on various hull forms to establish what the hull design shall be like in a given sea spectrum. Therefore, even though not in the SOR, as a naval architect you should ensure the design does not produce unwanted motions in the expected sea states of where the vessel is operation. Regardless whether seakeeping is a criterion and written into the SOR or not.

In other words, would you design and build a boat that meets the SOR and nothing else, or would you design and build a boat that has taken a holistic approach and reviewed many aspects to provide a “well balanced” design, inc the SOR? The designer needs to make sure that there is no resonance, if there is, mitigate them. In other words a holistic approach, despite the sea conditions in HK being benign, a review of all considerations is always required. That is the role of the naval architect, to check everything, whether in the SOR or not and establish, is it a problem. The SOR is just the "basic" list of wants. No different to using Class rules for structural design. Designing just to satisfy Class rules does not make the structure "fit for purpose"; just makes it pass rules. As you have already identified it is why some boats have good reputations and some not so. A well balanced design takes experience and a large database. It does not come from the pressing of buttons or a good sales pitch.

I tend to agree, yet the operators I have liaised with appear somewhat paranoid about the bridge and think otherwise. Time shall tell...as always