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New generation method for compartment connections

Posted on November 1, 2018

Already for some twenty years, the Probdam damage case generator has a feature, called compartment connections, for generating complex intermediate stages of flooding. This tool has been improved so that a multitude of complex intermediate stages will be generated, instead of just a single one previously. This results in a more realistic flooding pattern of compartments through the defined compartment connections. As an example, see the picture below which shows the previous mechanism, as well as the present one. In this example compartment A is initially damaged and compartments B and C are being flooded due to the compartment connections with compartment A.

Calculation performance in PIAS

Posted on October 23, 2018

SARC is already present in the maritime software industry for more than 35 years. Our goal is to create software for naval architects which programmed from the mind and practice of a naval architect, in order to make it quick and easy to use. One of the most challenging parts of software programming is to make the software is fast enough for the most comprehensive calculations. As years got by, on one hand computers became faster, while on the other hand there is a tendence to calculate more and more.  Therefore the software programmers had to make sure they would keep up with the developments of the hardware.

For a long time past a PC generally had one processor, containing only a single processing unit (core). That implies that the computer can process one task at a time. However, there is a tendency where a computer is equipped with multiple real or virtual processors. So, this technology enables a program to execute tasks parallel and in 2005 PIAS has been adapted for that facility by making the following tasks available for simultaneous processing:

  • Intact and damage stability.
  • Probabilistic damage stability.
  • Computation of intersections between bulkheads and/or compartment boundaries in PIAS’ Layout module.

So, over more then a decade ago we already developed hyper-threading within PIAS. In later years hardware companies kept developing their processors which also led to new developments in our software. Dual threading processors have led to multithreading in PIAS. Additionally, modern CPU’s are equipped with AVX (Advanced Vector eXtensions) which facilitates eight concurrent arithmetic operations in one processor cycle. More information can be found in the white paper ‘Acceleration of PIAS by hardware support‘ from May 2017.

PIAS offers two speed enhancing packages:

  • PIAS/ES 1, with original Windows threading facilities, limited to two threads (dualthreading).
  • PIAS/ES 2, containing AVX and application of Windows thread pool technology. Optimized for 4 to 8 threads but limited to 8 threads (hence its name octothreading).

We have done some tests for an “average” PIAS ship, with damage cases up to 8 simultaneous damaged compartments, resulting in 525 damage cases, without so-called “external subcompartments”. (Measured timings are in seconds)

Hopper dredger stability integrated into PIAS’ Loading module

Posted on October 16, 2018

Hopper dredger stability (e.g. dr-68 or Bureau Veritas N.I. 144) computation used to be present in PIAS in a separate module Hopstab. In February 16 of this year a new version of PIAS’ stability module Loading was released, where all hopper stability effects have been integrated (and enhanced, compared to Hopstab). The dr-78 and dr-68 stability regulations require a hopper dredger also to comply with requirements of probabilistic damage stability. This has been available for some decades in PIAS, based on the hopper particulars as defined in Hopstab. Recently, PIAS’ probabilistic damage stability module has been updated, so it now applies the hopper and loading data as defined in Loading. The new modus operandi of probabilistic damage stability for a hopper dredger is discussed in the manual.

After this enhancement, module Hopstab has become obsolete and will be discarded. This marks the end of the software renewal process around hopper dredger stability in PIAS, and implies that specific hopper-related data files from elder projects cannot be used anymore for computations. Please refer to the hopper stability manual chapter for further discussion.

Split hopper vessels

2006/87/EC technical requirements for inland waterway vessels

Posted on October 11, 2018

The applicable rules are available in all European languages: https://eur-lex.europa.eu/legal-content/EN/ALL/?uri=CELEX%3A32006L0087

Per 1 juli 2009 is in de Binnenvaartwet vastgelegd dat eigenaars van jachten langer dan 20 meter een Certificaat van Onderzoek (CvO) moeten hebben. Dit certificaat is nodig om op Europese binnenwateren te mogen varen. Destijds is er een overgangsregeling ingesteld die eigenaren tot 31 december 2018 de gelegenheid geeft om een geldig Certificaat van Onderzoek te verkrijgen.

Alle drijvende werktuigen die na 1-7-2009 gebouwd zijn moeten worden gecertificeerd (Certificaat van Onderzoek) en de nieuwe eisen en overgangsbepalingen voldoen. Drijvende werktuigen van voor 1-7-2009 (waarvan de kiel is gelegd voor 30-12-2008) moeten per 31-12-2018 gecertificeerd zijn. Deze categorie drijvende werktuigen wordt aangeduid als ‘bestaande vloot’.

Er is in geen geval later dan 30 december 2018 een Certificaat van Onderzoek of Communautair Binnenvaartcertificaat voor Binnenschepen verplicht voor:

  • alle vaartuigen met een lengte van 20 m of meer
  • alle vaartuigen waarvan het product van de lengte, de breedte en de diepgang meer dan 100 m3 bedraagt (het onderwater blokvolume van meer dan 100 m3, exclusief kiel, zwaarden en andere aanhangende zaken, dus ook korter dan 20 m)
  • alle sleep- en duwboten, ongeacht de lengte, die zijn bestemd om de hiervoor bedoelde vaartuigen of drijvende inrichtingen te slepen, te duwen of langszij mee te voeren
  • alle passagiersschepen (vervoer van meer dan 12 passagiers naast de bemanning)
  • drijvende inrichtingen

Meer informatie kan gevonden worden op de site van IL&T: https://ilent.nl/misdebootniet 

Multiple windage areas

Posted on October 3, 2018

For the computation of wind heeling moments, in PIAS the windage area can be given. That used to be limited to a single contour, with some maximum number of points, which was sufficient for the common use the past 25 years. However, when importing the contour shape from a CAD system that maximum can easily be exceeded. For this reason this PIAS’ module Hulldef has been extended to accommodate a wind contour with a number of sub-contours (each with a resistance coefficient), with an unlimited number of points.

Customer case: ms Ostia

Posted on September 25, 2018

Type vessel: General / Bulk cargo for inland waterways

Rule dimensions:

  • L = 110,00 m
  • B = 10,46 m
  • D = 3,2 m
  • T = 3,2 m

Delivery: Lines plan for a single screw inland waterway vessel.

For Shipbuilding Solutions our engineers performed the lines plan design for a general cargo vessel built for the Dutch inland waterways. They started off with a general arrangement plan and made a unique design for the hull form. Besides the hull form design, they also have faired the vessel with Fairway to optimize the building process.

After designing the vessel there also have been made some Rhine container calculations with PIAS.

 

New setting “Righting levers denominator” in damage stability

Posted on July 31, 2018

Righting (and heeling) levers of stability are determined by dividing the righting (or heeling) moment by the ship’s displacement. In intact condition, the displacement to choose for that division is unambiguously that of the loading condition under consideration. In damage stability, the choice is not that obvious. However, the standard suggested by the relevant regulations has conventionally been “Constant displacement”, so that has always been the standard choice in PIAS. For some time now an alternative choice is also available — as presented in “MSC.1/Circ.1461, guidelines for verification of damage stability requirements for tankers” and “IACS 110 Guideline for Scope of Damage Stability Verification on new oil tankers, chemical tankers and gas carriers” — i.e. “Intact displacement minus liquid cargo loss”. The choice between these two alternatives is now available as a setting in PIAS, please consult the manual for more details.

SARC delivers on-board loading computer software for dry bulk ships Arklow

Posted on July 3, 2018

SARC has successfully delivered the on-board loading computer software for the new cargo vessel Arklow Villa (YN 730). This is the last ship in a series of ten 5,150 DWT traders that SARC has fitted out at Royal Bodewes Shipyard to Bureau Veritas class standards. They are all owned by Arklow Shipping and are being operated and managed by Arklow Shipping Netherlands. The first vessel in the series was be delivered in October 2015.

Bodewes & SARC
This is not for the first time that Bodewes has ordered the on-board loading computer at SARC. Other recent projects like the NB 803 Coralius; a unique LNG flex tanker that was nominated for the Next Generation Ship Award at Norshipping 2015 is also equipped with LOCOPIAS. At Bodewes they are using our PIAS software to calculate the stability of their vessels. The advantage of this is that SARC can use their PIAS-files for the base of LOCOPIAS, so there is no extra costs for input of ship data and the same files are used for the stability booklets.

The launch of the Arklow Villa has been filmed and uploaded to YouTube.

Stability criteria with PIAS

Posted on June 19, 2018

The stability required to ensure the safety of a ship, its crew and the environment is laid down in legislation. In PIAS the major part of legislation is predefined, readily available, while the underlying parametric editor facilities allows the definition of less frequently used or very specific criteria. More information about manipulating and selecting sets of stability cirteria can be found in the manual: https://www.sarc.nl/images/manuals/pias/htmlEN/stabcrit.html.

We have created a document to provide a coherent and clear overview of the stability criteria. This is achieved by collecting legislations set by the IMO, European Union and local authorities, and categorizes these legislations by operating area and ship type. Please send us a message if you are interested in this document including the .req files for PIAS.

Earlier this year we have informed you about the update of the stability criteria within PIAS: https://www.sarc.nl/update-of-stability-criteria-in-pias/ .

Surface export from PIAS/Fairway

Posted on May 15, 2018

Although the NURBS surface method is not very suitable for the hull design process as such, it is widely used for interfacing. So, when a hull design is to be used downstream, e.g. for engineering, CFD analyses or visualization, the Fairway hullform has to be converted to a set of NURBS surfaces.

The first step is identifying larger, four-sided areas, which is essential because its four-sidedness is an intrinsic requirement of the NURBS. The next step is to convert these surfaces to NURBS. In this paper the mathematical nitty-gritty will be omitted, the interested reader is redirected to a special conference paper on this subject.

Anyway, the result is that by some neat mathematical processing, a patchwork of NURBS surface is created with the following properties:

  • Guaranteed gap-free along common boundaries between adjacent surfaces.
  • The number of vertices of the resulting NURBS surfaces is determined automatically, and is the minimal required to achieve this gap-freeness, as well as accurate representation of the original Fairway surface.

This method is baptized LEANURBS (an acronym for Lowest Effective Amount of NURBS). Its implementation in Fairway is demonstrated by the following sequence of screen dumps, from which the first shows the ship hull in Fairway. The second is a screen dump where the hull is subdivided into four-sided regions and the last one is the IGES file in Rhino.

 

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