It's not really, you're used to seeing tankers and box ships with a single prop, Aotearoa has twin props, it's like the Mærsk Tripple E, twin props, unusual but becoming more common.
It's not pods, if they had pods they could have done aways with the rudders. This is a photos of a Yamal Class LNG tanker, these are ice breaking tankers used on the run from the Yamal LNG terminal to China and Japan, as you can see with the pods azimuth pods, no rudder is needed. These vessels are also double acting, when breaking thick ice they move stern first.
They would have been building hull blocks for months before the keel was laid.
Yep, they don't muck around. Big money lost of they don't build commercial hulls on time and there'll be penalty clauses in this contract too around late delivery. HHI will already have the next VL ship build for that dock lined up and ready to go so they can't afford to stuff around on this build.
Mærsk went with twin engines for the triple E for a number of reasons, twin smaller engines allowed them to reduce the height of the engine room enabling them to add more containers, by using two propellers also allows a better distribution of pressure, which increases the propeller efficiency more than the disadvantage of using two engines, the triple E has a design service speed of 19 knots, the E class was 25 knots, the triple E uses 37% less fuel. So it's a combination of better efficiency and greater cargo capacity that has lead to Mærsk build 31 of these monsters.
Thanks KR. I was being literal when I said pods, not azipods but yes, it seems they will be even more pronounced “blimps” than even the tides, they start to seperate about 30 mtrs ahead of the transom.It's not pods, if they had pods they could have done aways with the rudders. This is a photos of a Yamal Class LNG tanker, these are ice breaking tankers used on the run from the Yamal LNG terminal to China and Japan, as you can see with the pods azimuth pods, no rudder is needed. These vessels are also double acting, when breaking thick ice they move stern first.
They would have been building hull blocks for months before the keel was laid.
A ships power requirement is simply determined through the need to push a hull threw the water and the required service speed. Her displacement tonnage gives us the amount of water needed to move. Her waterline length also is a factor and seeing as its 0500 here this morning I’m not going to look it up. From memory, her max speed will be determined by 2.5 x square root of her waterline length.....provided you have the power to move her.
Not me sir! I’m not a naval architect. I can tell you that cavitation is bad, that there are measures to reduce it but I wouldn’t know jack about propellor design apart from a few obscure facts which are probably irrelevant.
I suspect it is to protect the shaft line and the twin props in the ice class configuration noting there a more stringent hull strength requirements. In additionexposed shaft lines and seals can be a problem in ice conditions.
Thanks for those links, that’s interesting info.
The other aspect of this is docking. The overhang from the point where the hull plating rises to the stern structure this needs to be supported in dock. This can either be done by reinforincing the hull to be able to suspend the structure (look at the Hobart DDG) or providing supporting structure (which is necessary for alarge ships with heavy structure. For a hull with 'A' brackets this can mean a skeg under which blocks can be fitted. The other option is encasing both shaft lines as has been done in this case (and the triple E as shown above) so blocks can be placed under these extensions. Encasing the shaft line does impose a drag penalty but that is not a huge issue if you are not looking at very high speeds (say a sustained speed 20knots and above).
No doubt the new Manawanui will inherit its namesakes .50cals for point defence as fixment should be relatively straight forward as per the old vessel just require the best placement with the widest arcs and by the looks could possibly be on split levels either side looking at the unique deck layout. 2 mini typhoons would be good but I could see this particular ship keeping them old school stock mounted unless funding permits.