Heavy Lifting Stability Criteria

[Guest-3-12-09-9-21]

Hereema has been using semi-submersible twin hull vessels their lifting and pipelaying operations. This, in my admittedly ignorant opinion, seems to be a much more inherently stable vessel. I would much rather trust a large semi-submersible platform to lift and swing a heavy load than a mono hull vessel relying solely on dynamic ballasting to keep the load from swinging out of control.

I imagine that the chief reason for the new construction vessels being mono rather than twin hull is due to the capital construction costs.

http://findarticles.com/p/articles/m...g=artBody;col1

..."The size of the vessel will be approximately 220m x 88m. The lift capacity of the cranes has to be determined, but will at least be comparable to the capacity of the Thialf. The dual crane capacity of Thialf, the largest crane vessel in the world and part of HMC's fleet, is 14,200 tons."...

I assume that with a width of 88m it would be twin hull?

--Chuck

[murdomack]

86 mtrs was the beam measured at the hulls on the Hermod and the Balder. At the deck it is over 100 mtrs. I've lived on these two many times in the past.
The Thialf is given as 88 mtr which I am assuming is also at the hulls so the new one may be a similar design. The Thialf was built for McDermott's as the DB 102. The last time I lived on it was about 1992 and I thought it was not as stable as the other two when the weather got up, mind you it placed a 5000 tonne module with a good breeze blowing. It's had lots of work done to it around 2000 so I don't know what it is like now.

http://hmc.heerema.com/Default.aspx?tabid=438

[Guest-3-12-09-9-21]

Found the Thialf - they are working to install the module on the Tahiti platform in the gulf of Mexico. We just had Tropical storm Edouard come rolling through and it looked like they were riding a hell of a lot better than we were.

It is impressive looking - I'll try to post a picture when I get off the boat (not enough bandwidth to send picture now).
--Chuck