Moving a camel through the eye of a needle with GNSS

作者：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-metreheight差异，开发了浮动系统。为了安全地从生产大厅和降低系统中安​​全地操纵Ferus，Neptun Shipyard开始使用Leica Geosystems GNSS技术。

Blind trust as a prerequisite

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,55 m wide and 7.5 m high。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 tons此时 - 就在16米深底座。然后，必须将降低系统正确定位到几厘米，并以某种方式固定在上下移动的唯一选择。

随后，储罐被淹没，从而使整个降低系统沉没。最终，只有18-m的2 m上层建筑突出水面。就as there is enough water on the deck, the tug boat captains receive their go-ahead. The FERU is then moored at the bow and the stern.

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 cm最多。拖船队长和Feru上的飞行员无需将自己定向到港口或右舷。船尾的船长只看到米在他面前高耸的灰金属墙上的米。两位队长都需要盲目信任飞行员。这意味着必须知道降低系统的精确位置。否则，避免与上层建筑的碰撞是不可能的，这些不可避免地会损坏FERU和降低系统。

Using GNSS technology for construction sites

A GNSS-supported measurement process with Leica Geosystems technologies is now used in all the steps. Multi-frequency GNSS antennae were installed on the starboard-side bow and stern of the superstructures on the lowering system. The accompanying dual GNSS receiverLeica ICG 80安装在控制室中。该装置最初是由Leica Geosystems开发的，用于土木工程中的重型建筑机械，不仅可以确定确切的位置，而且还可以预测潜在的运动。随后，通过使用A的一次性测量测量来确定触角与降低系统相关的相对位置Leica Nova TS60total station. In one of the shipyard's halls, aLeica Viva GS10GNSS高精度接收器安装在一个相对庇护的位置，作为精确测量的固定点。

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.

The control software for the lowering system used 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.

Navigating FERU 1396 out of the eye of the needle took only 10 minutes – a time that would have been impossible for a safe undocking, especially at a day with winds of force six because, due to its dimensions, the FERU poses such a big target for the wind.

更快 +更多灵活=更多利润

The MEYER Group has been successfully using measurement solutions from Leica Geosystems for many years. During the conception phase, GNSS solutions from various suppliers were evaluated. The main criteria were:

• Positioning accuracy of 2 to 3 cm,even on moving ground
• 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至 + 40 c并且是飞溅防水。

Lars Wegener and Kevin Schemmel, part of the survey team at NEPTUN shipyard, reported,“Relocation of 1396 went well.”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.