Huge Semi-Submersible Ships

OK, makes sense. But, I still like catamarans ....

 

Wayne
Catamarans have too small a waterplane area for many applications, 'weight sensitivity' is the issue.

A side wall floating dock in submerged state has the same sort of waterplane as a catamaran. If that makes you feel any better, pretend it's an inverted cat The heavy lift submersible ships have just enough waterplane and reserve aft to control the pitch but it looks so tiny compared with the ships displacement. But they are built to class stability requirements just as a floating dock.

 

How is this for size. The Blue Marlin ship transport.

http://www.wmmw.in/c/Blue_Marlin_ship_transport/

http://www.youtube.com/watch?feature=player_embedded&v=NVqji1vIFYI

 

Not big enough.

 

Nice link.

 

I can see why Leo ended up hiding from his own thread...

 

All right, tell us why.

 

That's why. Right there...

 

Instead of a catamaran,

Could we use a split bow? Like an upside Catamaran?

Then you could place bigger ships right down the middle?

 

I guess we are all missing the idea. These ships sink only to allow cargo to slip overhead then slowly pump out its ballast tank to regain their freeboard and regular waterplane area. It works like a car jack.

The freeboard may be low but these ships travel only in calm weather.

 

Don't they go around the Capes?

 

The displacement of the semi-submersible has to be the weight of the semi-submersible plus the weight of the vessel it is carrying.

If a catamaran was used the draft, length and/or beam of the semi-submersible would have to be larger for the same displacement as a monohull.

Also, a catamaran would have bending/twisting loads to deal with.

 

It depends on the physical characteristic of the cargo.

Once we were tasked to find the feasibility of towing a large bulky cargo to cross the Gulf. The cargo is to be loaded on a barge and towed by a tugboat.

The NA,s calculated the stability of the cargo and barge and considered the wind factor, then calculated the towrope horsepower needed for the varying sea state condition. We searched google weather for a weather/sea state for a date that will fit the window given, added the fudge factor and chose a suitable tugboat for hire. Add to that the cargo surveyor to ensure the correct lashing of cargo and deck modification, the safety inspector (from the contracting agent) and a ship condition surveyor to ensure the tugboat is in condition to do its job.

Once everything fitted in, we were all in the wharf to check everything and off they go. Takes a lot of logistics to do that.

 

Thanks,

I am past the right side up catamaran idea. Now I would just like an upside down ship look.



They actually do make the submersibles that way, for the reason I am thinking.

But, I think most are not made that way, because most are designed to go around the capes...... Not fun sea states with an 'open' bow, even if you have a LOT of reserve buoyancy. All that extra ocean going everywhere would be a LOT of unnecessary weight. And would take your cargo with it ....

http://static.worldmaritimenews.com/wp-content/uploads/2012/12/State-of-the-Art-Heavy-Lift-Vessel-Dockwise-Vanguard-Ready-for-Sea-Trials-.jpg -- Dockwise Vanguard

 

Giant catamaran for removing oil platforms: http://gcaptain.com/giant-catamaran-pieter-schelte-to-carry-worn-out-north-sea-oil-rigs-ashore/