Hydrodynamic analysis with OrcaFlex is used to confirm and improve upon closed form analytical solutions developed by STA.

Designs have been developed for cruise ships up to 333m length with gross tonnage 150,000 and a starting collision velocity  of 6 knots.

Efforts on the project were interrupted in September 2017, by Hurricanes Harvey, which effected our Houston office, and Irma, which effected our Caribbean interests.

The post Cruise Ship Collision Barrier appeared first on Stewart Technology Associates.

Sewol Salvage: Stewart Technology Associates worked as Technical Advisors to Shanghai Salvage Company using STA software and were responsible for all dynamic analysis of the complex lifts in the open ocean environment.  All lifts are dynamically sensitive and involved cutting edge marine salvage dynamics. Analyses were performed with waves in the time domain using FEA (OrcaFlex).

Marine Salvage Dynamics of Sewol Salvage raised with ZPMC 12,000 ton floating crane and 1,200 ton lifting frame.

32 HMPE upper slings, 8 balance slings, 34 pairs of steel lower slings.

Fully coupled 6 DOF time-domain dynamic analyses in OrcaFlex with diffraction forces on the Sewol and ZPMC crane barge.  All individual sling tensions computed during all stages of the Sewol Salvage.

Sewol wreck transfered to semi-submerged floating dry dock in open ocean.  OrcaFlex time domain dynamic analysis of three main vessels, lifting frame and all slings.

The following video describes how STA has examined the issues of unusually low freeboard and trapped water on the pontoon deck.

The video provides a description of how OrcaFlex is used to cope with time domain calculations of the wave motions of the floating dry dock when the deck becomes submerged and the buoyancy of the wing tanks is of critical importance.

More details of the accident can be found at:

gCaptain

Wikipedia

The  portfolio item below provides a short OrcaFlex Tutorial with a Mooring Analysis example.

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Wireline view of SPM CALM Buoy modeled in OrcaFlex.

A Suezmax tanker is moored via a hawser.  View list of STA software.

Suezmax tanker seen in shaded perspective view in OrcaFlex, moored to SPM CALM buoy during squall analysis.

The portfolio item below provides a short OrcaFlex Tutorial with a Mooring Analysis example.

The post SPM Squall Analysis appeared first on Stewart Technology Associates.

Cable dynamics may not be something you think of when you talk about going out on an oil rig. Any time you are on the water with an anchor, drilling equipment, or anything else, you have to look at the dynamics of a cable because there are various factors that need to be considered.

Decoupling Deep Ocean Cable Dynamics

Above figure shows lazy-wave geometry for a Tyco SL14 SPA cable in 6000 meters water depth for US Navy application.  Cable floats have been designed by STA for a section (shown blue) and analyzed in OrcaFlex in a sea state 6.  The tension range at the top end is low and easily tolerable.  The tension range at the touchdown has been reduced to less than 1 kN.

Cable laying and support vessel in OrcaFlex, shown above.

There are going to be cables connected to your rig. They go up and down as the water goes up and down. When you are drilling, you have to consider the depth of the sea. It is very much like an anchor. An anchor is only going to be effective if it is able to reach the bottom. Otherwise, it is simply going to dangle from the boat and cause you to drift. The anchor is therefore not as effective as it could be and all because you were unprepared for the depth of water that you would be in. the same goes for the cables. Understanding depth is vital to the success of your project.

Waves

The physics of waves should be explored in depth when you’re going to be out on the water. You need to know when they are going to occur, where, the height of the waves, and more. All of these are going to play a role in the equipment you choose and the training you give your employees. Failure to recognize the importance of waves can result in problems on the water – and you could end up injuring someone or destroying a part of the rig.

Movement on the Rig

There’s going to be movement on the rig due to all sorts of factors – wind, weight of what’s on the surface, and even movement of employees. These are going to be factors when calculating the cable dynamics.

Overall Stability

Stability is critical and when you’re on a rig or even fishing, there are going to be cables or other lines in the water and then connected to your boat or rig. When working with steel catenary risers, they are responsible for the fluid transfer from one area to another. If the cable dynamics haven’t been explored to the fullest, the transfer could be broken simply because of one variable that was missed during the setup, such as bigger waves or deeper water.

Accident Prevention

It’s important to prevent accidents and when you are dealing with being on a rig that could be on the water for months at a time, you have to think about everything. The more you know about potential accidents on the water, the more you can prepare your employees for what could happen. Having analysis at your fingertips as to what you could experience can be invaluable when you are looking to train employees, purchase equipment, and stock the rig before leaving the shore.

The post 5 Reasons To Consider Cable Dynamics appeared first on Stewart Technology Associates.