Most seaworthy type of ship?
Discussion
Ok, so you find yourself in the middle of an ocean in sea conditions that make the 'perfect storm' look like a millpond. What type of ship would best be able to cope/would you feel safest on? Would bigger be better e.g Nimitz carrier, Iowa class battleship (I know they don't venture out now) or something like an ocean going tug or even one of the self righting life boats the RNLI use?
The one with the worse stability.
It may seem counter intuitive but the more stability a ship has the more it rolls (both amplitude and acceleration increase).
Thus the best solution to poor seakeeping is to put weight up high.
A submerged submarine is even better since below about 4x wavelength there is no impact from a storm. just don't get caught on the surface.
It may seem counter intuitive but the more stability a ship has the more it rolls (both amplitude and acceleration increase).
Thus the best solution to poor seakeeping is to put weight up high.
A submerged submarine is even better since below about 4x wavelength there is no impact from a storm. just don't get caught on the surface.
MBBlat said:
The one with the worse stability.
It may seem counter intuitive but the more stability a ship has the more it rolls (both amplitude and acceleration increase).
Thus the best solution to poor seakeeping is to put weight up high.
A submerged submarine is even better since below about 4x wavelength there is no impact from a storm. just don't get caught on the surface.
Sorry that sounds insane and against physics. top heavy will mean more movement until its upside down.It may seem counter intuitive but the more stability a ship has the more it rolls (both amplitude and acceleration increase).
Thus the best solution to poor seakeeping is to put weight up high.
A submerged submarine is even better since below about 4x wavelength there is no impact from a storm. just don't get caught on the surface.
Simpo Two said:
If not a submarine, then maybe one of those rigs with big feet under the surface. Or maybe just a spherical pod with a long pole underneath with a big weight on the end. That would keep you the right way up and dampen the vertical movement.
A good friend of my father was on board this rig when it capsized:[[ http://en.wikipedia.org/wiki/Ocean_Ranger ]]RobDickinson said:
Sorry that sounds insane and against physics. top heavy will mean more movement until its upside down.
Its not against physics - its all about the ships response to the sea, which in a storm is anything but flat.A very stable ship will tend to stay perpendicular to the local sea surface, which means that on the side of the wave it can be at quite an angle to the vertical. A less stable ship (note not unstable) will not follow the sea quite so closely, thus have lower accelerations.. Add a bit of damping such as bilge keels to the equation and you can quite quickly reduce the amplitude as well.
If you still think that's counter-intuitive don't look up anti-roll tanks, http://en.wikipedia.org/wiki/Antiroll_Tanks as this uses the movement of water from side to side to counteract roll.
One example I worked on a while back, unmodified in beam seas the model tests (and reports from the full sized ship in question) showed roll amplitudes of 45degrees. Lowering the GM (ie reducing stability), increasing the size of the bilge tanks and putting in some anti-roll tanks and in the same beam seas the ship was just bobbing up and down with no roll.
jimreed said:
Simpo Two said:
If not a submarine, then maybe one of those rigs with big feet under the surface. Or maybe just a spherical pod with a long pole underneath with a big weight on the end. That would keep you the right way up and dampen the vertical movement.
A good friend of my father was on board this rig when it capsized:[[ http://en.wikipedia.org/wiki/Ocean_Ranger ]]Having worked offshore, I wouldnt like to be on either.
MBBlat said:
Its not against physics - its all about the ships response to the sea, which in a storm is anything but flat.
A very stable ship will tend to stay perpendicular to the local sea surface, which means that on the side of the wave it can be at quite an angle to the vertical. A less stable ship (note not unstable) will not follow the sea quite so closely, thus have lower accelerations.. Add a bit of damping such as bilge keels to the equation and you can quite quickly reduce the amplitude as well.
If you still think that's counter-intuitive don't look up anti-roll tanks, http://en.wikipedia.org/wiki/Antiroll_Tanks as this uses the movement of water from side to side to counteract roll.
One example I worked on a while back, unmodified in beam seas the model tests (and reports from the full sized ship in question) showed roll amplitudes of 45degrees. Lowering the GM (ie reducing stability), increasing the size of the bilge tanks and putting in some anti-roll tanks and in the same beam seas the ship was just bobbing up and down with no roll.
That's me and RobDickinson put in our place then!A very stable ship will tend to stay perpendicular to the local sea surface, which means that on the side of the wave it can be at quite an angle to the vertical. A less stable ship (note not unstable) will not follow the sea quite so closely, thus have lower accelerations.. Add a bit of damping such as bilge keels to the equation and you can quite quickly reduce the amplitude as well.
If you still think that's counter-intuitive don't look up anti-roll tanks, http://en.wikipedia.org/wiki/Antiroll_Tanks as this uses the movement of water from side to side to counteract roll.
One example I worked on a while back, unmodified in beam seas the model tests (and reports from the full sized ship in question) showed roll amplitudes of 45degrees. Lowering the GM (ie reducing stability), increasing the size of the bilge tanks and putting in some anti-roll tanks and in the same beam seas the ship was just bobbing up and down with no roll.
Gassing Station | Boats, Planes & Trains | Top of Page | What's New | My Stuff