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-metreheight不同,一个浮动的降低系统开发ed. To manoeuvre FERUs safely out of the production halls and off the lowering systems, NEPTUN shipyard started using Leica Geosystems GNSS technology.

Blind trust as a prerequisite

The lowering system is a shippable floating dock. It consists of a reinforced concrete pontoon with additional superstructures on top. The float itself is150 m long,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.

当准备将其运输到现场时，首先在液压系统的帮助下将FERU提升到生产大厅内。然后，它滑过陆地上的硅胶涂层路径，直到降低系统在水中等待的码头墙。当船将船放在降低系统上时，拖船拉动巨大的Feru - 重量超过40,000吨at 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, only2 m of the 18-msuperstructure protrudes above the water. As soon 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

现在在所有步骤中都使用了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弓和船尾上。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是新系统的第一个未加工的发电站，将是世界上最大的邮轮公司最新的邮轮之一的核心。首先在降低系统上先前测量的位置安装了两个ICG80 GNS接收器，并激活了控制室中的接收器。使用此安装，可以将FERU从生产厅移动到降低系统上的精确位置。为了从降低系统中解除FERU，将两个触角安装在其上。

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.

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

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,即使在移动的地面上
• Immunity to environmental factors, such as temperature fluctuations and salt water
• 无线和无线电数据传输。

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,“With the help of this technology, we have literally made big things happen. You could clearly see that we practise the motto of the MEYER Group, ‘Stronger together’, because, in addition to the workers of both shipyards, many specialists were involved; experts for nautical map technology, classical coastal navigation and tugging methods.”

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.