What determines a ship's ability to withstand sea state 9?

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In summary, the ability of a ship to withstand extremely high sea states is determined by the ratio of its length to the crest wavelength, as well as the design and materials used in its construction. Factors such as weight, cargo, and the expertise of the captain also play a role. There are standard procedures and calculations used to determine a ship's stability, but the wisdom of the captain is also important. In some cases, a longer hull may provide a more comfortable ride, but it can also be more vulnerable to breaking in rough seas. Finally, the purpose and destination of the ship may also influence its design and ability to withstand extreme conditions.
  • #1
Ibexe
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What exactly determines a ships ability to withstand extremely high sea states?
 
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  • #2
What research have you done so far? What have you found out?
 
  • #3
phinds said:
What research have you done so far? What have you found out?
From looking at videos of ships in high sea states and looking at the data for sea states i believe it has to do with length of the vessel and the materials used
 
  • #4
That is correct, it is the ratio of the length of the ship to crest to crest wavelength the higher that ratio the less amount of pitching the ship will experience; but, at the same time the ship hull must be designed and built with materials that give it sufficient strength to endure the longitudinal bending forces as it spans the wave troughs. The weight of the vessel is also a factor, because a heavier or well ballasted ship will be better able to cut trough the wave peaks and reduce the pitching height caused by the impacting wave. Obviously, there are additional factors associated with preventing internal damage from shifting of cargo, both solid and liquid.
 
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Funnily enough I was wondering recently about something similar.
The scenario is you have a container ship coming out of Rotterdam in Netherlands, with goods bound to Cork in Ireland.
The first stage going down the English channel/La Manche should be straight forward enough, but after that the ship has to do hard right turn, whilst simultaneously encountering all the North Atlantic can throw at it.
I guess there must be standard procedure, and if things don't look good they wait in the Channel for a while.
 
  • #6
Primarily the determination is via the relationship of the center of gravity to the center of buoyancy. As a ship floats at a level that varies by weight for any given actual weight the center of gravity varies by loading and the center of buoyancy varies by overall weight of displacement. A ships stability calculation uses a set of tables known as "cross curves of stability" These are particular to a ship or class of ship and give the righting moments for weight and metacentric height. A little Google search will show quite a bit on how these work.
 
  • #7
Ibexe said:
What exactly determines a ships ability to withstand extremely high sea states?
The wisdom of the master is most important. Otherwise it really depends on the type and size of the boat.

A long hull may give you a more comfortable ride, but when a long hull straddles two big waves it will break it's back. I would prefer to survive than be comfortable. The complex wave interference patterns such as found off the SE coast of South Africa have broken the backs and so taken many vessels over 100,000 tonnes.

If you are in a sailing boat and a storm is rising, first reduce sail, next heave to, then run with the wind with a small storm jib, or under bare poles, then if it gets too fast, put the drogue out from the stern.
A light-weight racing boat is a liability. The design rules make winning boats dangerous in challenging seas. The race winner will be the boat that just manages to survive the storm. To win at any cost, costs lives.
 
  • #8
Baluncore said:
The wisdom of the master is most important. Otherwise it really depends on the type and size of the boat.

A long hull may give you a more comfortable ride, but when a long hull straddles two big waves it will break it's back. I would prefer to survive than be comfortable. The complex wave interference patterns such as found off the SE coast of South Africa have broken the backs and so taken many vessels over 100,000 tonnes.

If you are in a sailing boat and a storm is rising, first reduce sail, next heave to, then run with the wind with a small storm jib, or under bare poles, then if it gets too fast, put the drogue out from the stern.
A light-weight racing boat is a liability. The design rules make winning boats dangerous in challenging seas. The race winner will be the boat that just manages to survive the storm. To win at any cost, costs lives.
Hmm surprisingly the ship I am looking at is going to be used all the way from South Africa all the way to the Kara sea I am looking around to find the best design to prevent extreme damage when transporting 3 vehicles around for joyriding around the world lol
 
  • #9
rootone said:
Funnily enough I was wondering recently about something similar.
The scenario is you have a container ship coming out of Rotterdam in Netherlands, with goods bound to Cork in Ireland.
The first stage going down the English channel/La Manche should be straight forward enough, but after that the ship has to do hard right turn, whilst simultaneously encountering all the North Atlantic can throw at it.
I guess there must be standard procedure, and if things don't look good they wait in the Channel for a while.
I wonder what caused them to take such a hard right.
 
  • #10
Ibexe said:
Hmm surprisingly the ship I am looking at is going to be used all the way from South Africa all the way to the Kara sea I am looking around to find the best design to prevent extreme damage when transporting 3 vehicles around for joyriding around the world lol
Surprisingly .... lol !
If you keep secrets when asking questions you will not get useful answers and you will waste the time of all the respondents.
 
  • #11
Ibexe said:
Hmm surprisingly the ship I am looking at is going to be used all the way from South Africa all the way to the Kara sea I am looking around to find the best design to prevent extreme damage when transporting 3 vehicles around for joyriding around the world lol
Is this question an exercise in an engineering class?
 
  • #12
Baluncore said:
Surprisingly .... lol !
If you keep secrets when asking questions you will not get useful answers and you will waste the time of all the respondents.
What secrets am i hiding? Lol you lost me there comrade
 
  • #13
Mark44 said:
Is this question an exercise in an engineering class?
No just a curious question when i seen youtube videos on ships in high sea states
 
  • #14
Ibexe said:
Hmm surprisingly the ship I am looking at is going to be used all the way from South Africa all the way to the Kara sea I am looking around to find the best design to prevent extreme damage when transporting 3 vehicles around for joyriding around the world lol
For liability reasons, we cannot provide advice on dangerous activites. Consult the ship's builder and follow their safety guidelines. Thread closed.
 

What determines a ship's ability to withstand sea state 9?

The ability of a ship to withstand sea state 9 is determined by several factors, including the ship's design, construction materials, and operational procedures.

What is sea state 9?

Sea state 9 is a classification used by mariners to describe rough sea conditions, with wave heights reaching 14-19 feet and wind speeds of 47-54 knots.

How does a ship's design affect its ability to withstand sea state 9?

The design of a ship plays a crucial role in its ability to withstand rough seas. Ships with a larger displacement and a wider beam (width) are generally more stable and better able to handle high waves.

What materials are used in constructing a ship to withstand sea state 9?

Ships designed to withstand sea state 9 are typically constructed using high-strength materials such as steel, aluminum, or composite materials. These materials have the strength and durability to withstand the forces of rough seas.

How do operational procedures affect a ship's ability to withstand sea state 9?

The way a ship is operated and maintained can also impact its ability to withstand rough seas. Proper maintenance and adherence to safe operating procedures can help prevent damage and ensure the ship is prepared to handle rough sea conditions.

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