Groot Cross-Bow design

Came across this idea being used to reduce wave action on commercial ships

the tank test showing the action



and the launching of a full size boat



if these youtube links dont work first time, I will edit them later to correct them

the sales pitch

 

It's like the Axe bow concept, with a extra that the containerstack on the front is shielded for green water.

 

From a description of the vessel in "The Motorship":
The Groot Cross-Bow uses the ‘wave-piercing’ principle, which the designer, Groot Ship Design, says “cuts through the waves instead of riding onto the sea”. Compared with conventional bow designs with flare, a vessel with a Groot Cross-Bow is claimed to have a smoother ride with less pitching and less wasted energy and thus lower consumption of fuel oil. Another claimed advantage is better comfort for crew in heavy conditions and less risk of damaging the cargo in heavy seas or bad weather.
http://www.motorship.com/news101/chinese-built-ships-have-novel-dutch-bow

 

Geesss...when are people going to realise this is just very clever marketing. There is no such thing as a wave "piercing" bow...never has been. Not in the sense that it reduces XX and YY and ZZ as always claimed.

 

I didn't observe anything 'unusual' in that tank test video. Did I miss something?

 

"Bow Wars" is the latest thing in vessel marketing... everyone needs an angle (pun intended) to be competitive.

 

I noted that the bow design in the tank test is not the one on the ship itself.

The usual 'flare' on big bows results in the bow 'digging in' on heavy seas, while I suppose this design will provide the same wave protection with much reduced 'shudder and rise' typical of the big boats.

Also, it seems to be a 'package' deal, not just the bow.

Some intriguing notes from the web site

"Both designs features not only the Groot Cross-Bow but also a high payload and flexible cargo intake in combination with a speed of over 12 knots. The fuel oil consumption is designed to be lower than other vessels of similar size. Carisbrooke expects a reduction in fuel consumption up to 30% compared to vessels of equal tonnage. The EEDI for the Super Green 8500 is calculated to be 9.72, thought to be better than most other designs, and well below the 2025 required index of 13.3"

 

This is marketing.

Nothing scientific nor engineering based in its prose. It is just words, words to fool and coerce the person reading it.

 

..... as is your detailed rebuttal - perhaps you have some technical basis for your dismissal of a multi-million dollar, government and industry funded process ?

I'm not blindly favouring this design, but I am not inclined to dismiss the project at this stage, considering the money spent on it by so many professional people.

 

Just simple naval archiecture - hydrodynamics.

As noted here:http://www.boatdesign.net/forums/bo...g-myth-design-ingenuity-30296.html#post318566

where I was trying to explain to Will, just ignore the heckling from RickW an uninformed poster. It is just a short read, of 2 -3 pages if you wish to read all.

Another brief over view here: http://www.boatdesign.net/forums/boat-design/reserve-buoyancy-37589-2.html#post456511

 

Yes, thanks for that, an interesting read.

However, in this case I don't think its just a question of 'wave-piercing' hype. The whole hull and drive method are re-designed, and an SOR for flexible cargo configuration, optimised fuel consumption for this size craft seem to be worthy goals.

Obviously we will be interested in the actual results, I guess if they go ahead with the next four boats, that will be the proof.

 

Can i say that all ships are wave piercing objects...? it's the way they do it that's interesting for us.

 

I like this "Bow Wars" approach to improving container ships. By & large their main goal is to allow better performance while smashing through wave after wave on the high seas. The tapered edges on the top will help reduce wind drag, and the bow flare helps deflect the waves. For rough sea conditions, all in all it's an improvement.

In calmer seas, it's extra weight & wind drag you would't get any benefits from it. Yet, weather systems are more eratic now so merging to a design like this makes sense. If I were skippering a big cargo boat I would love to pound some waves with one of these boats.

I like it.

http://www.youtube.com/watch?v=I8yr_StC3uw

 

Smashing through waves:-

1) Requires greater energy to maintain speed = inefficient
2) More load on the structure (more weight) and more potential for fatigue cracking
3) Securing system for cargo requires greater fixing and load paths = more weight
4) Crew performance is reduced owing to constant accelerations, they becomes fatigued too.

The goal is to reduce "smashing" as you put it. Avoidance is the objective.

To allow waves to pass by decoupled from the motion of the vessel, it reduces all 1~4. The ultimate solution of 1~4 is a SWATH.

 

Avoidance would improve performance, no? That's my main point. I do think this design will help keep the bow up. As for hull stresses, this depends on the cargo loading. As far as crew stress, I have sailed in very heavy seas on a large ship. If you're in the bow then yes, you're in for a wild ride. Hard to sleep. If you're further aft the ride is much smoother. I sleep like a baby in rough seas so it all depends on the individual.