Crane goes swimming with the tide?

Dutch consulting engineers Royal Haskoning is promoting a floating con­tainer crane concept based on a kind of catamaran hull.

Hafkoiungs floating crane concept, in this case deployed as an extra quay crane.

One of the arguments put forward by Haskoning is that ship sizes are going up dramatically and rapidly towards the suezmax limit of 12,500 TEU, but mainly in the height and width dimensions. Ship length is not increasing in proportion to ship size. In broad terms, capacity of a modern panamaxship is around 15 TEU/m of length while capacity of a suezmax ship is around 34 TEU/m of length.

Terminal operators have generally found that no more than 4-5 cranes can be deployed efficiently along the side of a ship so clearly the industry is faced with a dilemma. Furthermore, the bigger the ship the harder it is to maintain crane pro­ductivity, because of the size of the load path, sway problems, driver “parallax” ef­fects, and so on.

A floating crane, deployed on the far side of the ship moored alongside the quay, adds another “hook”, but without the expense of an indented dock such as Ceres Paragon in Amsterdam. Unlike a concrete dock the floating crane can be towed or, if engined, power itself to any other part of the port or loaned to a neighbouring port.

Playing pontoon

In the Haskoning design, the crane is mounted on two pontoons. They would house generators, fuel and ballast tanks and other installations and their dimensions and shape determine stability to a large degree. This concept allows the crane to transload containers from the mother ship to feeder ships or barges moored between the pontoons and outwith the rear pon­toon (see big figure).

Although the pontoons would pro­vide basic stability, dynamic motion sup­pression systems may have to be fitted as well to enable the driver to pick up or spot containers more easily. Rigid moor­ing (eg vacuum mooring with Cavotec Moorfender) of the feeder ships and barges may help in this respect.

In Haskoning’s vision, a port such as Rotterdam handling suezmax vessels would use four or five large cranes on the shoreside in the normal way, supple­mented by a similar number of floating pontoon cranes on the seaward side.

The ship plan could be built round the floating cranes transloading directly to barges for inland waterway distribu­tion. Alternatively, the barges could be used as buffer stacks for rehandling in off-peak hours. Hatch covers can be stored on one of the pontoons but Haskoning suggests it would be better if they were all landed on the apron by the shore-based cranes to prevent them getting mixed up.

Oldest idea in the book

Floating cranes are probably the oldest type of crane and the most universal. As Haskoning points out, they need never have idle time since they can be spread around the port and shared among op­erators according to work load.

They can also be used at shallow wharves, by placing them in a “strip” be­tween the quay wall and mooring dol­phins. In this case the backreach is used to pick up and land containers (see small figure), so the hatch covers have to be landed on a structure between the pon­toons. For humanitarian relief or military support operations, ships could be han­dled offshore, with barges or small craft taking the containers to the shore.

Haskoning’s floating crane concept, in this case deployed as an extra quay crane

In this case, the crane enables a big ship to use a shallow berth

Vocabulary

tide – прилив

Dutch – голландский

promote – продвигать

hull – корпус

deploy – размещать

extra – дополнительный

put forward – выдвинуть

dramatically – впечатляюще

rapidly – быстро

mainly – главным образом

dimension – размер

m = metre

found – p.p. from find – находить

generally – обычно

face – столкнуться

furthermore – более того

harder – труднее

maintain – поддерживать

productivity – производительность

path – траектория

sway – качание, раскачивание

parallax – параллакс; смещение

moor – швартоваться

expense – расход

indented – зд. специальный

unlike – в отличие от

concrete – бетон

tow – буксировать

power – переместиться

loan – предоставить взаймы

mount – монтировать

house – вмещать

shape – форма

determine – определять

stability – остойчивость

degree – степень

transload – перегружать

feeder – вспомогательное судно-снабженец

outwith – снаружи, за пределами

rear – задний, тыльный

stability – остойчивость

motion – движение

suppression – сдерживание

pick up – поднимать

spot – размещать

rigid – жёсткий

moorfender – швартовный кранец

vision – видение

supplement – дополнять

distribution – распределение

alternatively – в качестве альтернативы

buffer – амортизатор, буфер

stack – стеллаж

hatch cover – крышка люка

land – выгружать

apron – бетонированная площадка

prevent – предотвращать

point out – подчёркивать, указывать

idle – холостой, нерабочий

spread – распространяться

share – распределять

shallow – мелководный

wharf – (-ves - мн.) – причал

place – размещать

strip – полоса

dolphin – тумба

backreach – вылет стрелы до груза с

задней стороны крана

structure – сооружение

relief – зд. помощь

craft – флот