Moving a camel through the eye of a needle with GNSS

Author:Beate Wesenigk

TheNEPTUN shipyardis part of the MEYER Group based in Papenburg, Northern Germany, and enormous floating objects are constructed in it – Floating Engine Room Units (FERUs), the ‘power stations’ for giant cruise ships. Specialised in FERUs, this shipyard in northern Germany, faces a big challenge – FERUs are not constructed in dry docks, but in various production halls above the water line. To bridge the2-metre高度difference, a floating lowering system was developed. To manoeuvre FERUs safely out of the production halls and off the lowering systems, NEPTUN shipyard started using Leica Geosystems GNSS technology.

盲人信任作为先决条件

降低系统是一个可刷的浮船坞。它由钢筋混凝土浮桥组成，顶部还有其他上层建筑。浮子本身是150 m长,宽55 m，高7.5 m. Inside the pontoon, there are water tanks. During docking, FERUs are fixated with the help of steel-cable winches. The lowering system has a dedicated control room located in the front tower on the starboard side. From there, all systems are monitored and controlled.

When it is ready to be transported off-site, a FERU is first lifted inside the production hall with the help of a hydraulic system. It is then slid across a silicone-coated path on land up to the quay wall where the lowering system is waiting in the water. When the ship is positioned on the lowering system, tug boats pull the gigantic FERU – that weighs more than40,000 tonsat this point – right above the16-m deep docking pit. The lowering system must then be correctly positioned down to a couple of centimetres and secured in a way the only options for movement are up and down.

Subsequently, the tanks are flooded, thus sinking the entire lowering system. Ultimately, only18-m的2 m上层结构在水上突出。一旦甲板上有足够的水，拖船船长就会接受他们的批准。然后将Feru停泊在弓箭和船尾。

This undocking process itself can be likened to the metaphor of a camel going through the eye of a needle describing a very narrow opening – the distance between the undocked ship and the superstructures is only120厘米at its most. The tug boat captains and the pilot atop the FERU have no means of orienting themselves towards the port- or starboard side. The captain at the stern only sees metres upon metres of grey metal wall towering in front of him. Both captains need to blindly trust the pilot. This means the exact position of the FERU atop the lowering system must be known. Otherwise, avoiding collisions with the superstructures is impossible and these would inevitably damage the FERU as well as the lowering system.

Using GNSS technology for construction sites

现在，所有步骤都使用了Leica Geosystems技术的GNSS支持的测量过程。多频GNSS天线安装在降低系统上的上层建筑的右舷侧弓上。随附的双GNSS接收器Leica iCG 80is fitted in the control room. This installation, originally developed by Leica Geosystems to be used on heavy construction machinery in civil engineering, cannot only determine the exact position but also make predictions about potential movements. Subsequently, the relative position of the antennae in relation to the lowering system was determined with a one-time tachymetric measurement using aLeica Nova TS60总站。在造船厂的一个大厅中Leica Viva GS10GNSS high-precision receiver was installed in a relatively sheltered spot, serving as a precise-measured fixed point.

FERU 1396, the first undocked power station with help of the new system, will be the centrepiece for one of the newest cruise ships for the largest cruise line in the world. Two iCG80 GNSS receivers were first installed at the previously measured locations on the lowering system and the receiver in the control room was activated. Using this installation, it was possible to move the FERU from the production hall onto an exact position on the lowering system. To undock the FERU from the lowering system, both antennae were installed on it.

降低了系统的控制软件in the control room links GNSS data, terrestrial and maritime maps, providing real-time data as well as forecasting data for the projected movements of the lowering system and the FERU to all participants in the undocking process. To react immediately to changes and give out appropriate instructions the pilots and tug boat captains use Leica CS35 field tablets. In addition to the real-time data and movement projections on their CS35 field tablet, the pilots and tug boat captains also see exactly how much they have to steer to starboard and port to leave the lowering system without damage.

从针头浏览Feru 1396仅需10分钟，这是一个安全的撤离的时间，尤其是在每天用力六的风中，因为由于其尺寸，Feru构成了如此大的目标为了风。

Faster + more flexible = more profits

多年来，Meyer Group已成功使用Leica Geosystems的测量解决方案。在构思阶段，评估了来自各种供应商的GNSS解决方案。主要标准是：

• Positioning accuracy of 2 to 3 cm,即使在移动的地面上
• 对环境因素的免疫力，例如温度波动和盐水
• Wireless and radio-less data transfer.

The survey team headed by Ralph Zimmermann decided for the Leica Geosystems solution. The iCG80 GNSS receivers were developed to withstand harsh conditions on construction sites, work error-free from-20 C to + 40 Cand are splashwater resistant.

Lars Wegener and Kevin Schemmel, part of the survey team at NEPTUN shipyard, reported,“ 1396的搬迁进展顺利。”Zimmermann expanded,“在这项技术的帮助下，我们实际上使大事实现了。您可以清楚地看到，我们练习迈耶集团的座右铭“更强大”，因为除了造船厂的工人外，还参与其中。航海地图技术，古典沿海导航和拉扯方法的专家。”

This system benefits the MEYER Group in various ways for ongoing tasks as well as for future projects. The entire process of moving and undocking FERUs has become much safer because of the provided real-time positions, movement projections and calculations for tug control help to avoid collisions. Furthermore, it is possible to move and undock objects that extend beyond the bow and stern of the lowering system. The speed, precision and reliability of the system unaltered by weather conditions is a perfect fit for MEYER Group who plans to build three cruise ships in Papenburg starting in 2019 and, in the future, two per year in Turku, Finland.