news
Image of Moon pool complexity: from good to great engineering

Moon pool complexity: from good to great engineering

What the heck is a moon pool and why does it matter?

Last updated 4 months ago
It is not every day that you get to talk about designing better-performing moon pools. And probably the first question that comes to mind is: What the heck is a moon pool? Well, simply stated, it is a hole in the hull of a ship to access the water and ocean floor underneath.

Article by Jenn Schlegel (source)

Moon pools are typically found in high-tech fall-pipe and drilling vessels, diving support boats and scientific research ships. Essentially, any type of boat that has to release something safely and correctly from bottom of the hull needs a well-designed moon pool. This could be something as simple as a cable or as heavy as a piece of steel pipeline or as mission critical as a submarine full of marine scientists.

A top-performing moon pool takes the heavy lifting out of advanced geotechnical projects. With a drill tower and moon pool, drilling vessels can perform drilling and subsea well services directly from the bottom of the vessel. For fall-pipe vessels like the Simon Stevin (pictured), the moon pool provides a way to deposit rock via a long pipe directly on the seabed, which is useful for activities such as land reclamation, port infrastructure work and ocean foundation reinforcement for offshore wind farms.

From a scientific side of things, moon pools can help research teams access hard-to-reach places in the ocean, like parts of the frozen Arctic, safely and securely launching submarines and other scientific equipment. They can also enable teams to work directly inside the vessel and not outside in the harsh sea-faring elements.

In a nutshell, the real engineering question at hand is: how do you design a good hole in a boat? One that can improve performance and save on fuel consumption -- which is positive news for budget-savvy owners as well as the environment.

How to design a good moon pool?

This was exactly the question on the minds of the engineers at Vuyk Engineering Rotterdam working on the design of the Simon Stevin. A moon pool can obviously cause some performance and safety issues, ie. you don't just cut a hole in the vessel in any old place. Optimizing a moon pool design means finding the right balance between hundreds of possibilities including customer specifications, cost options and various performance factors.

“Our customers set the technical specifications,” says Erwin Put, operational director, Vuyk Engineering Rotterdam. “We work within these boundaries according to a specific budget and timeline. It is our goal to come up with the best possible solution within those boundaries. The marine industry is still an extremely customer-centric and customized industry. You have to understand the huge amount of capital invested in a single vessel project. The customer has a wish-list when it comes to performance. By the time we come into the picture, our time and budget is limited.”

Since moon pools are usually bespoke, one-off designs, they can differ greatly from vessel to vessel. Moon pools can typically cause issues, like unwanted water flows, increased resistance, increased fuel consumption and additional turbulence. To engineer a moon pool properly you have to cover a lot of angles, therefore experts tend to use CFD and optimization tools to get to the right result.

https://vuykrotterdam.com/images/uploads/news/Moon_Pool_Optimalization_Vuyk_Engineering_Rotterdam.gif

Enter the CFD engineers

Back to the engineers at Vuyk Engineering Rotterdam and the Simon Stevin. One engineer in this story had already worked on optimizing a specific moon pool design for a drilling vessel using Simcenter™ STAR-CCM+™ software for the CFD work. After completing five simulation studies, he managed to take the resistance level of the moon pool on the vessel’s hull down by 2.4%. But looking at the big design picture, one of his colleagues realized that with the right tool they could do more. He was thinking about HEEDS™ software.

HEEDS is a design space exploration software package that can interface with all types of CAD and commercial CAE packages as well as in-house and customized tools. It takes a big picture overview of the engineering work and various software packages and tools involved and optimizes the overall design and engineering process. In other words, it can up an engineering game from very good to great – no matter what tools or solutions are used.

From good to great engineering

Knowing that there was room for improvement, the team at Vuyk used HEEDS to investigate further. Running a design exploration loop revealed better design options, trimming the overall resistance by more than 1% from the previous resistance level. Decreasing resistance by more than 3% can mean a lot for any huge vessel – especially ones with moon pools. It translates into an immense fuel savings and overall annual cost reduction. Not to mention the environment impact of not burning all that fossil fuel. “Using HEEDS doesn’t necessarily save time,” says Put. “It’s the quality of the engineering and final design that results in big-picture savings such as less fuel consumption, lighter overall design and better structural performance.”

Quality engineering provides a competitive advantage

Time and budget issues will always be there, but using quality optimization techniques like HEEDS means that Vuyk isn’t competing on price or an hourly rate; they are competing on the quality of the engineering they deliver and the time it takes them to do it. “Working with HEEDS requires a different mindset as an engineer,” says Put. “You need a big picture view as an engineer. You need to think about the whole design and where it would work best to apply certain improvements.”

Today, this mindset has clearly paid off. The Simon Stevin, which has been active since 2010, continues a wealth of tough projects including hauling and installing protective layers of foundation rocks for the German North Sea wind farms and contributing to a more sustainable future for everyone.

https://vuykrotterdam.com/images/uploads/news/Siemens_Moon_Pool_Heeds_%28WEB%29.jpg

In the case of research vessels, a moon pool allows technicians and researchers to lower scientific equipment and even submarines directly into the ocean.

For complex drilling vessels and fall-pipe vessels like the Simon Stevin, a moon pool takes the heavy lifting out of advanced geotechnical projects. With a drill tower and moon pool, these vessels can perform drilling and subsea well services directly from the bottom of the vessel.

For fall-pipe vessels like the Simon Stevin, the moon pool provides a way to deposit rock via a long pipe directly on the seabed, which is useful for activities such reinforcing the ocean foundation for offshore wind farms.

A moon pool is certainly not the first thing that springs to mind when you talk about naval architecture and marine engineering. But then you aren’t designing almost 200-meter-long deep-water mining and fall vessels like the Simon Stevin every day.

Need to get in touch with the team?

We are all ears
VUYK engineering