Wave-piercers - marketing myth or design ingenuity?

Those who have been following the rather spritely debate on the Dare to Say No thread would have noticed that the question of whether wave-piercer's are a reallity - the result of design intent - or the result of clever marketing to describe the way in which a vessel is driven, has sprung up.

Personally I firmly believe it is the former. Surely a vessel that is designed intentionally with little reserve buoyancy in its forward sections, in order that it will pass through smaller waves can legitimately called a wave-piercer.

As you will note in this quote from AH, he disagrees with me. No point in a debate with no opposing argument!
And I would agree that any vessel, regardless of form, can be forced to bury itself if driven too hard. A wave-piercer is no different in this regard to any other vessel.

 

Will
You are in good company. Some half baked academic might argue that Multimarine are kidding themselves with their USD3M VSV Maryslim. If it is a marketing ploy they have wasted a good deal of money adding strength to the deck and cabin structure. I would back their knowledge and experience on this matter though. Clearly others have.
http://www.youtube.com/watch?v=AwgaLSF03gk&feature=related


Then there is Earthrace. The current record holder for circumnavigation under power - just a tad slower than sail using much larger boats. Maybe someone should have told them it was a marketing ploy before they started going through waves rather than over them.
http://www.youtube.com/watch?v=dxJOJDGchTs
http://www.youtube.com/watch?v=AwgaLSF03gk&feature=related
Is that green water over the whole boat - can't be; wave piercing is just a marketing ploy.

Someone needs to inform Joyon that his amas cannot possibly carve through waves. They have to go over them:
http://www.youtube.com/watch?v=3m_9o_Bdtew

There are people who try to get experience from text books and others who have experience by actually getting out there and doing things. The latter know what they are talking about.

Rick W

 

I would like to see some footage of the Earthship in a sea state as shown on this CFD video from ~13 sec forward:

http://www.youtube.com/watch?v=dxJOJDGchTs&feature=related

 

Is this a wave piercing bow http://en.wikipedia.org/wiki/File:Royal_Sovereign_class_diagrams_Brasseys_1906.jpg :?:

Is not Earthrace a boat with severe field of vision problem and severe visibility for other boat problem (including human vision and radar) http://green.autoblog.com/2007/03/24/tragedy-at-sea-earthrace-team-hits-fishing-boat-off-guatemala/ :?:

 

I can understand the premise behing AH's point of view. He is simply pointing the the physics behind what is happening. It's hard to argue with them, as they fact. It's really a question of intent.
If a designer shapes a vessel such that it intentionally passes through a surface chop, I believe it can be classed as wave-piercing. (If it passes through big seas, we can safely assume that its a submarine - intentional or otherwise!

As for Earthrace, it is a high profile example, but necessarily a good one... it's whole existence is a marketing ploy!

 

The boat pictured is intended to pass through more than chop. Look at the height of the air intakes. These are the only portion intended to stay above the surface. The video clip linked above on Earthrace states that it "submarines" and was designed to do so.

The hull linked here was not intentionally designed to wave pierce but it does:
http://www.boatdesign.net/gallery/showphoto.php/photo/14406/size/big/cat//ppuser/18624
It is an unavoidable outcome of its shape and operating speed in a certain size wave. It pierces waves with the hull covered by water over its full length as it passes through - I get very wet doing this so I speak from first hand experiencing. I am not speculating from what I have read in some text. It is not a marketing ploy or a noun; it is a simple fact. It pierces waves - as in a verb. It goes THROUGH waves not over them.

Going upwind the wave piercing is controllable but wet. Going downwind I have buried the hull to the point where I was pedalling in water. That is when I back off. I am not convinced I could keep control. I would be very interested to see footage of Earthrace in a sharp sea going downhill.

Rick W

 

Will

Ok, ignoring the "my feelings are" qualitative rubbish; which i must say, is just another twist and turn. Since what do we usually get from the world according to all things analytical are true, is now suddenly is no longer valid (anything is better than addressing ones own lack of comprehension demonstrated time and time again)....well, make of that what you will, doesn't take to be a rocket scientist to comprehend that!

So, back to basics. This, since being a time -delay debate, not real time, shall be iterative.

1) How do boats float?...this is a serious question. One must start from the beginning to make clear the assumptions and comprehension, before moving forward. (Again something that is clearly lacking above).

So, sounds simple, but what is the answer....then Q two shall follow.

 

Yes, yes ... I know where you're going with this....
And as stated in my last post, I can't dispute the physics of your position. If the forces acting 'down' upon the vessel are less than those acting 'up' upon it then it will submerge to the point where the situation is reversed. This will be the case for any vessel, regardless of shape. I have no argument with Archemedes!
Marketing and/or misunderstanding has no doubt led to the inappropriate use of the term wave-piercer. But that doesn't render the term itself invalid.
I post again a pic of what I consider to be a true wave-piercer. I am entering the lions den here, as it is a commercial catamaran, so definitely within your field of expertise!
Its hulls, without question, are intended to pass through smaller waves.

 

Now. You can argue that it is doing nothing more than any other hull would do if presented with a set physical circumstances. And you'd be right. But again, it is intent.

 

Will

"..Its hulls, without question, are intended to pass through smaller waves..."

"..You can argue that it is doing nothing more than any other hull would do.."

Agreed on both counts. (Pity you spoilt my fun )

"..But again, it is intent..."

OK, if you know the "intent" is to pass through smaller waves, this is already recognising the situation that the length of the wave is much smaller than the length of the vessel. Yes?

 

yes..

 

Ok.

So, if the wave length is much smaller than the length of the boat, what will its amplitude be, the same, higher or less than the freeboard? Since you're a bright cookie, you will realise it shall be less than the freeboard.

So, a wave, a small wave, with an amplitude that does not immerse the deck, will just pass by, so to speak.....agreed?

 

Well, you got at least one thing right...

Unless I misunderstand the intent of your statement, that would depend upon the freeboard. In the case of a conventional vessel, yes that should be the case. In the case of the wave-piercing cat I posted above, then no.

With the above caveat... agreed...

 

No debate in the "intent" here:
"The 3 million USD, 72 feet VSV (Very Slender Vessel), named MarySlim, will enable the bold and intrepid to explore the globe - quickly, safely and with the maximum fun-factor to boot. The pioneering powerboat features wave-piercing technology that allows it to plough through storms no other vessel would dare to tackle. Her revolutionary design makes the MarySlim ideal for cruising the globe and adventuring in the most adverse of conditions and with minimal crew.

The stylish and ultra-sleek boat can cut through waves in any conditions thanks to the extremely sharp line of her bow. The hull and windscreen have been constructed to submerge several feet and withstand the pressure of 110,231 lbs of water – so when bad weather is turning regular mariners back to port, the MarySlim will be heading confidently out to sea."

Irrespective the original proposition was not about design intent but whether wave piecing is a noun or verb. Wave piercing occurs - boats will pass through waves particularly the long slender hull that I initially referred to. The consequence of doing this will depend on how they are designed to cope with it.

The attached shows one of my designs that happily copes with green water over the cabin top. It will PIERCE waves and will do it without drama or loss of control.

Rick W

 

The post is, and i shall repeat for the hard of reading:

"..whether wave-piercer's are a reality - the result of design intent - or the result of clever marketing.."