May 24, 2017 version

Initial Landscape

Prevent the ingress of water into damaged hulls for gashes exceeding 50 meters (three compartments).

Background:

For centuries ship hulls have been divided into watertight compartments to reduce flooding risks from hull breaches or to ship liquid goods. The Song Dynasty Chinese author Zhu Yu wrote of watertight compartments in his book, Pingzhou Table Talks, written from AD 1111 to 1117. (Wikipedia).

A typical STENA cargo ship has 12- 15 water tight compartments below the water line of about 3200 cubic meters each.  In response to the sinking of large ships from below water line gashes (like the Costa Concordia), a

change has been proposed to increase the current SOLAS requirements of maintaining buoyancy

and stability with two compartments flooded to now three compartments. The risk is determined

through a calculation that assesses the probability of survival when hull breaches occur. (see IMO

reference at the end of this Landscape)

Executive Summary:

Our landscape search has found recent research with dynamic modeling and testing showing that

the abrupt ingress of water after a hull breach can heel a ferry or large ship rapidly with

only one compartment flooded.

The most effective and economical method we have seen demonstrated is the introduction of High

volume compressed air into the breached compartment(s). This slows the rate of ingress and

somewhat limits the total amount of water in the breached compartment.

We are introducing a concept of using commercial air bladders that would deploy in the breached

compartment to add buoyancy and stability while limiting the amount of water in the

compartment.

Though there are thousands of patents for devices and systems to address hull breaches, and a

few commercial patch products, none of them are for the scale of this problem.

Both Universities of Strathclyde, Glasgow and Centrale, Nantes are key research centers for damaged ship stability and survivability.

John Molander for Rockdale Innovations

May 24, 2017 version

Landscape research:

Theory and Modeling:

In our Landscape research we have found numerous technical papers published on the effect of

hull breaches on buoyancy and stability of large passenger ships and ro-ro ferries. New computer

techniques have allowed researchers to move from steady state equations to dynamic time

domain modeling. The key learning from the models and tank simulations is that instability and

capsizing can happen quickly due to the rapid ingress of water in moderate seas even when only

one compartment is flooded. The abstracts of two papers most pertinent to STENA are shown

below.

Transient Flooding on Large Passenger Ships https://www.researchgate.net/profile/Dracos_Vassalos/publication/228781104_Transient_Flooding_on_Large_Passenger_Ships/links/

00b49525abcf728ee3000000.pdf

This paper summarises research into effects of transient stages of flooding on stability of modern large passenger ships (LPS). The sample study-case configuration exhibits high vulnerability to attaining excessive angles of heels due to inrush of water, possibly leading to immediate capsizing even for small damages. The underlying physical mechanism derives from effects of multiple free surfaces, which cannot be analysed in traditional manner and must be simulated in the time domain. Though typical numerical model for such time domain simulations is capable of pinpointing the potential problems, it displays ambiguity in relation to (a) modelling of roll motion energy-dissipating rate when subject to damage and (b) modelling of water flow by simplified Bernoulli equation.

Progressive Flooding stages of Damaged Ro-Ro Vessels

http://offshoremechanics.asmedigitalcollection.asme.org/article.aspx?articleid=1456912

Roll-on/roll-off vessels appear to be sensitive to rapid capsizing due to an abrupt ingress of water caused by maritime accidents. As a result of the damage creation, the flooded ship can experience intermediate stages, which might be more devastating than the final condition, as the sudden loading could significantly alter the ship stability characteristics. Far from a probabilistic analysis, the paper under study presents the state-of-the-art in regards to flooding physics by treating some relevant important topics. It sheds light on the transient and progressive flooding stages, focuses on relevant factors, and suggests combinations between factors that strongly affect the flooding before the steady state is reached. Furthermore, the authors comment on some points, which remain difficult to take into consideration either numerically or experimentally, and propose, where found necessary, recommendations for a more reliable assessment of the flooding process. This review shows that the intermediate flooding phase depends upon many factors, and its assessment could be adequate in calm water condition. The effects and interdependency between these factors still require further investigation. Therefore, we recommend carrying out a wide range parametric investigation into these factors, which consider their interdependency and encourage the application of the design of experiments methodology.

John Molander for Rockdale Innovations

May 24, 2017 version

We have identified two “Centers of Excellence” that have conducted research and published many

of these technical papers.

Professor Dracos Vassalos is a leading researcher on goal based survivability and has written

several papers on ship stability after damage. They have ongoing research work on ship stability

in the hydro labs at Strathclyde University in Glasgow. Dr. Vassalos is active in the international

organization for ship stability. He is presenting at the June 5, 2017 Ship Stability Conference in

Belgrade. www.shipstab.org

This research center in Nantes France uses modeling and hydrodynamic tank testing to evaluate

ship stability. Professors Mallat, Rousset, and Ferrant have written numerous papers on this topic

and have ongoing research projects in this field.

Possible Solutions for Hull Breaches

John Molander for Rockdale Innovations

May 24, 2017 version

Patent Art

In our research we have found thousands of patents on devices and systems to address hull gashes

and prevent the inflow of water. The earliest dates to 1897 and depicts a device inserted through

the hole that expands and clamps plates over the hole with a screw clamp. Numerous variants of

this have been patented in the following years. Almost all of these are limited to small puncture

holes and not long gashes. Later versions use bags filled with expanding

foam or air to seal the leak.

Other approaches in the patent art include water proof meshes that are

deployed over the gash surface with electromagnets or straps to hold

them in place.

In our initial search we have found nothing in the patent art that would

seal a 50 meter gash below the water line.

Commercial Products

Self Healing Materials--

We have found an interesting “self healing” technology from High Impact Technology, LLC that uses

a urethane coating infused with superabsorbent polymers. It is used to coat the inside and outside

of water and fuel tanks for military use. The link to their website shows an impressive video of

high velocity rifle shots going through the coated tank with no leaks.

http://www.hit-usa.com/fuel-cell-systems.php This may be useful for small corrosion breaches

but not for those caused by collisions.

High Volume Compressed Air—VTT research Finland

Air compression inside a flooded tank of a damaged ship can significantly delay the flooding process if the ventilation is restricted. This is a notable issue that needs to be considered for example in the design of cross-flooding devices. The problem is studied through systematic full-scale tests with a decommissioned ship, where the ventilation level of a flooded tank could be altered. Comparative time-domain flooding simulations have been performed by using Bernoulli's equation for compressible fluid for calculation of the air flows. The analysed measurements are used to validate the applied numerical method and relevant conclusions are drawn. http://www.sciencedirect.com/science/article/pii/S002980181200368X

John Molander for Rockdale Innovations

May 24, 2017 version

This solution was implemented with commercial marine air compressor equipment and valves

and significantly slowed the water ingress rate and total water ingress into the water tight

compartments. The experimental results on a full scale decommissioned ship correlated well with

the calculated models. This option is relatively low cost and has no impact on cargo space.

Commercial Air Bladders (bags)

In this option we foresee a typical 2m x 2m marine grade bladder that can expand in height up to

10 meters. (many of these are currently designed to hold fuel or potable water) The bag folds

down into a 0.5 meter height before deployment. Multiple bag units would be mounted on the

ceiling of the water tight compartment to minimize cargo storage impact.

If a hull breach occurs the air bags are deployed with compressed air pushing downward until

they contact the solid floor or cargo forming vertical columns. Any water in its path is compressed

by the bags and pushed out of the hull opening. Multiple bags means if one is punctured or

damaged the other bags complete the job. The bags provide buoyancy and minimize sloshing of

water in the compartment (a cause of ship instability). When the ship is in dry dock the bags are

deflated and removed.

Wessex Emergency Underwater repair packs

Hull repairsRepairs can be effectively carried out underwater when the hull of a vessel is damaged below the water line. If the damage is slight, i.e. where the integrity of GRP structure is not threatened in terms of mechanical strength, but with glass fibre exposed, there is the possibility of water ingress into the laminate, the UW43HV can be trowelled onto the damaged zone and faired to shape. If it is possible, the diver will

John Molander for Rockdale Innovations

May 24, 2017 version

prepare the surface of the damaged area as directed. The resin and hardener components are then mixed on board the ship and taken below in a closed container to the repair zone. The diver applies the UW43HV epoxy to the damaged hull with the large broad bladed spatula, firmly pressing the epoxy onto the GRP substrate. This action is necessary to 'squeeze out' the water between the structure and the first application of resin. With the initial application of resin in position it is possible to build up the epoxy thickness required, fairing to the contour of the structure as the material is applied. This type of application will prevent water penetration between the glass fibre and resin.If the underwater damage is severe and there is a gouge, say 12mm to 25mm thick, or a split in the hull allowing an ingress of water, thoroughly impregnate a section of the polyurethane foam with the UW43HV epoxy mix. As already detailed, this is achieved by laying the pre-cut foam pad onto the polyethylene sheet provided and working the resin into the foam with the broad knife supplied.The impregnated material is then wrapped in the polyethylene sheet for the diver to take down to the damaged zone. He will push the resin/foam pad into the gouge or split with the broad knife, forcing the material into the deepest sections of the damaged area. This operation will have an immediate self-sealing effect and the hydrostatic pressure will not only hold the impregnated foam in place, it will also compress the repair material in the gouge or split thereby restricting the flow of resin from the foam. The UW43HV will cure in the cellular structure of the foam and bond itself to the GRP laminate thus effecting a temporary repair to the damaged hull.

Detection:

Time is critical in the initial moments after a hull breach. Research with wireless hull strain gauges show promise for early detection and indication of the size/severity of a breach. Video in compartments can confirm the severity of the leak. The key findings of this US Navy study include that wireless sensors can be effectively used for reliable and accurate hull monitoring. Furthermore, the fact that they are low-cost can lead to higher sensor densities in a hull monitoring system thereby allowing properties, such as hull mode shapes, to be accurately calculated. http://www.tandfonline.com/doi/abs/10.1080/15732479.2010.495398

John Molander for Rockdale Innovations

May 24, 2017 version

References:

Royal Navy Hull Breach video

This video of the Royal Navy full scale simulator gives a real sense for the water flow and pressure

when a hull breach occurs. https://www.youtube.com/watch?v=xXC6U0NfJg8

SOLAS 90 with damage stability amendments

http://www.imo.org/en/OurWork/Safety/Regulations/Documents/SOLAS98final.pdf

The April 1992 Amendments

Measures to improve the damage stability of passenger ships came into force on 29 April 1990 and the April 1992 amendments to regulation 8 of Chapter II-1 mean that a slightly modified "SOLAS 90" standard will be phased in for ro-ro passenger ships built before that date during an 11-year period beginning on 1 October 1994. The phase-in period allowed depends upon the value of a ratio A/Amax, determined in accordance with a calculation procedure developed by the Maritime Safety Committee to assess the survivability characteristics of existing ro-ro passenger ships.

Those with an A/Amax value of less than 70% for example, had to comply with the amendments by 1 October 1994, the date on which the amendments entered into force. The complete phase-in period and degree of compliance is shown below:

ComplianceA/Amax value DateLess than 70% 1 October 199470%-less than 75% 1 October 199675%- less than 85% 1 October 199885%- less than 90% 1 October 200090%- less than 95% 1 October 2005

The application of the modified SOLAS 90 standard to existing ships means that a large part of the world's ro-ro fleet will have to be altered. In some cases the changes could be extensive and the high cost involved could lead to some of them being scrapped and replaced with new tonnage.

The improved fire safety measures for existing passenger ships which are introduced through amendments to Chapter II-2 include mandatory requirements for smoke detection and alarm and sprinkler systems in accommodation and service spaces, stairway enclosures and corridors. Other improvements involve the provision of emergency lighting, general emergency alarm systems and other means of communication. The new measures are being phased in between 1994 and 2000.

John Molander for Rockdale Innovations

May 24, 2017 version

The amendments are particularly important because they apply to existing ships. In the past, major changes to SOLAS have been restricted to new ships by so-called "grandfather clauses". The reason for this is that major changes involve expensive modifications to most ships. Because of the financial burden this imposes on the industry, IMO has in the past been reluctant to make such measures retroactive.

On this occasion the MSC decided that the new stability and fire safety standards are so important that they should not be restricted to new ships. The Herald of Free Enterprise disaster of 1987 and the Scandinavian Star fire of 1988 respectively both influenced the Committee in making this decision.

John Molander for Rockdale Innovations