SWATH design ideas

[Ilan Voyager]

I love the hype and hyperbole of the luxury market trying to sell an useless item disguising it with some "new" technology. We have some examples of failures of hyperbole : the famous ultra modern 150 millions automated and computerized square rig which was no faster than the 1860 Cutty Sark (18 knots) and sold 2 years later if I remember well 50 millions, or the Icon 5 seaplane, promising marvels, now bankrupt with some customers who'll never seen their money. That was simply a small seaplane they tried to sell for 400000 USD when you can get one better for 180000 brand new but it's a 28 years old design.
As old motorcyclist the are now selling expensive small bikes, like the KTM 390, with traction control and plenty of electronics to master the "overwhelming" power of 43 HP for 150 kg. Hype, over-engineering for a small bike...

Swath designs have been never discredited, but these designs are made for stability and pay expensively in money and performances for that. You had plenty of so called swath in reality wave piercing catamaran ferries since more than 30 years
Other solutions may also be efficiently used, like a classic displacement hull with foiler assistance.
Planing catamarans are thirsty beasts, and from my own experience are excellent vertebrae and hips destroyers in the small sizes. And it's useless to plane in truly big boats simply because length is the primordial factor of speed if you want some comfort and smoothness, so fast habitable catamarans are long, very long.
After the good old catamaran ferry Juan Patricio (70m meters long) is able of 53 knots top speed, and it's now used as ferry on the Mar de Plata at 40 knots to reduce the consumption.
You have also Cat Link V a wave piercing ferry catamaran which got the blue ribbon for crossing the Atlantic in 1998 at almost 40 knots (more than 50 knots top speed).
For a very fortunate oligarch that would be a nice spacious yacht as it can take more than 800 passengers. Length is far less expensive than other complications.

 

[BMcF]

I will keep an eye on it. It looks very interesting idea though, besides cost

Do you have a link you could provide that shows the concept?

 

[jehardiman]

I have seen news articles (sorry don't have handy now), top end luxury yacht market is designing SWATH and Planning catamaran with ballasts built in! When in motion, ballasts will be emptied making cat sail fast and in high seas / waves, fill the ballasts to make swath ie. comfortable sail for passengers.

What I have seen recently is a lot of "powerpoint engineering". And FWIW, ballasting down a planing cat into a SWATH for high seas is by inspection stupid from all sea keeping perspectives if one has done their due diligence.
Back in the mid 2010's there was an uptick in interest for SWATH yachts after the 2008 launch of SILVER CLOUD (41m, 14kt), but she look like a workboat which is to be expected given the 30+ years of operational experience of SWATH as commercial and military vessels. SWATHs fill a low motion, sustained speed niche; not a high speed runner that turns rock stable when stopped. This is not to say people have tried, and failed, but there are only a handful of other true SWATH yachts out there but many concepts. I think the most developed is Fincantieri FC 75 (75m, 18kt), these are people who have the skills and resources to develop, and produce, such a vessel and notice we are not talking speedsters here. And with a draft 5.5m (about 50% deeper than a comparable monohull), she will not be getting into many small exotic ports.

41m Abeking & Rasmussen catamaran Silver Cloud sold and renamed Nurja https://www.superyachttimes.com/yacht-news/yacht-silver-cloud-sold
Are Swath platforms the ideal superyacht design? https://www.boatinternational.com/yachts/yacht-design/are-swath-platforms-the-ideal-superyacht-design--715
Fc Swath 75 - Products - Fincantieri Yachts https://www.fincantieriyachts.it/en/products/fc-swath-75/

I believe SWATH started off as radical new design which was DISCREDITED by EXPERTS at the time!

If you have studied all the ONR and other documents, you will see that SWATHs were developed hard on the heels of the NATO Standard Frigate project of the late 1960's (which also gave us the NATO Standard Sea State definitions). SWATHs were rejected at the time for the frigate study because of the total SOR (really a stretch to meet the speed requirement no matter how good the helicopter and weapons platform was) and shipbuilder/government unease (i.e. never built one before so true costs were unknown). In the private sector, many people latched on to the flashy new idea (sound familiar?) but failed to realize the major engineering and human factors implications. These early poor performing and structural inadequate vessels gave SWATHs a bad name for decades. It was not until the mid 1980's that enough design experience was reached to realize that SWATHs and high speed catamarans are two different, uh, cats..... They have different strengths and weaknesses and therefore fill two different operational regimes and are designed in totally different ways no matter how much they appear similar.

SWATH, The Art Of Compromise - Martin, Ottaway, van Hemmen & Dolan, Inc. https://martinottaway.com/rhemmen/swath-art-compromise/

 

[BMcF]

I was fortunate to have been mentored by Dr. Don Higdon back in the late 80s, as he and I worked together to develop a fully digital control system for SWATH vessels. Don gets the credit for developing the first analog control systems for SWATHs...beginning with the "SSP Kaimalino" and has published papers from those days to support that. The performance of his systems and his overall hull designs clearly spoke for themselves. Many of the early commercial SWATHS, particularly from Swath Ocean Systems, Chula Vistat, CA, benefited from the application of Don's control systems, and, later on, from those produced by my company(s). To this very day, we make the superb SWATH designs produced by our own Ad Hoc Marine member, do amazing things in the realm of seakeeping, to include, even, zero- and low-speed stabilization. They are the best performing vessels currently supporting offshore wind farms. Bar none. So I'll ask, again, what new "needs" have arisen or are perceived that we have collectively failed to address. I'll add a postscript...THIS (pic attached) is the most recent "radical new SWATH design" my company provided control systems and technical/trials support for...I'll leave the opinions of this radical SWATH vessel to others. ;-)

 

[newbeeee]

Do you have a link you could provide that shows the concept?

Found the link, here it is https://www.autoevolution.com/news/...hnology-is-smooth-silent-gorgeous-153996.html

 

[newbeeee]

Found the link, here it is https://www.autoevolution.com/news/...hnology-is-smooth-silent-gorgeous-153996.html

Here it shows underwater profile https://www.pinterest.com/pin/301459768813311901/

 

[BMcF]

Found the link, here it is https://www.autoevolution.com/news/...hnology-is-smooth-silent-gorgeous-153996.html

Fast passenger ferries already there.

The shipyard in Norway that built that one is currently investigating a faster version for future production.

Almost 20 years ago a true SWATH leisure vessel long-range yacht was designed and built to rely on solar power in a hybrid power system to make possible extended voyages without refueling. We looked at providing an all-electric stabilizer fin system for it but unfortunately economic realities and personal health issues got in way of seeing that project to conclusion.

 

[Ad Hoc]

Found the link, here it is https://www.autoevolution.com/news/...hnology-is-smooth-silent-gorgeous-153996.html

what is "radical" about this...??

 

[bajansailor]

One 'radical' claim in the article is this -
"The yachting industry, for all the billions that it swallows or, perhaps, despite this, is a major source of pollution. Cruise ships are by far the biggest polluters, but personal yachts are not exactly guilt-less either."

Re how 'cruise ships are the biggest polluters', I wonder if this is just a personal grudge by the author against cruise ships, or does she have hard facts to substantiate this claim? I suspect the former.

This trimaran is also claiming to be very 'green' - zero emissions, woo hoo!
Groundbreaking 40m zero-emission trimaran concept Domus unveiled https://www.boatinternational.com/yachts/news/trimaran-concept-domus-unveiled

But how many carbon credits were 'used up' to build it?
One could reasonably say that the tall ship Cutty Sark had zero emissions as well (apart from the fuel for the cooking stove perhaps).

 

[jehardiman]

One could reasonably say that the tall ship Cutty Sark had zero emissions as well (apart from the fuel for the cooking stove perhaps).

Remember, whale oil is natural and renewable also!

 

[zstine]

Found the link, here it is https://www.autoevolution.com/news/...hnology-is-smooth-silent-gorgeous-153996.html

One issue with this design is that solar energy production is limited by roof space and since a SWATH has more drag (due to all that extra surface area) than a conventional surface running hull, this design compromised on solar-range and therefore on how 'green' the yacht is for the comfort of a SWATH. Most owners are going to crank up the generators to get where they want to go. The generators are rotary engine!?

 

[Ad Hoc]

.... since a SWATH has more drag (due to all that extra surface area) than a conventional surface running hull, ...

Well, like everything in design, that depends upon your frame of reference.
In a "generalised" statement one can say this is true.
However, at slow speed, not so.
The Swath may have more WSA, but it has less residuary resistance. The residuary resistance is a function of beam^2...and since the strut is very narrow, compared to a wide beam of a conventional hull, it is less, over all.
So at low Fns, the swath has less resistance, all other things being equal, length, displacement etc.

 

[MichaelGS]

Speaking of SWATH designs, what is everyone's thoughts on the Quad44?

 

[BMcF]

Speaking of SWATH designs, what is everyone's thoughts on the Quad44?

I'm sure our own Ad Hoc (John) can explain all the things that are very wrong with that concept design..at least as far as claiming it is a SWATH. . Shew...

 

[Squidly-Diddly]

SWATH flying boat with hydrofoils. Idea is instead of skipping across waves and taking full belly flop slams to the hull in take off and landing, you'd have a couple SWATH torpedoes doing wave piercing, and maybe some hydrofoils. Rather than getting up to planing speed, then to take off speed, you'd get to take off speed in wave piercing mode then pop off the water, maybe in WIG mode then full flying speed.