OCIMF published an Information Paper on Bridge Vulnerability, a detailed scientific study which offers both short and long term suggestions for preventing injury to staff during an attack.
OCIMF engaged a multinational defence technology company, QinetiQ, to conduct a two-phased study using computer software simulations to investigate the vulnerability of the bridge of a selection of tanker tonnages (from 30,000dwt to 300,00dwt) when coming under fire from an attack.
The aim of the study was to determine the likelihood of injury to, and the physical vulnerability of, seafarers on the bridge of a vessel when the vessel was subjected to attack by small arms weaponry. Simulations were carried out in order to determine the:
- Effects of firing a variety of weapons from numerous positions both in terms of range from the vessel and angle off the bow
- Likely penetration into the bridge
- Likely secondary fragmentation resulting from the shattering of windows
Based on the results of this study a package of protective measures are recommended.
Immediate measures
- Ensure that bridge windows do not shatter upon impact causing secondary fragmentation. Check that the glass is either laminated to a minimum Standard,(EN 1063 BR6 or its equivalent as discussed in the Annex to this Paper), or that a shatter proof film is attached to reduce the likelihood of glass fragments, this being of a comparable Standard. While noting that the study simulations only modelled fragmentation from glass (rather than other lining materials found on a bridge of a ship) ensuring that bridge windows do not shatter upon impact is the most important single measure found to limit injuries to bridge crew.
- Fit RPG protection to the bridge wings, either using proprietary net technology or a double chain link fencing arrangement. This must be used in association with a policy of keeping crew protected inside the superstructure to limit injuries caused by fragments from externally detonating rockets.
Longer term measures
Add armour protection to the bridge. Protection against 7.62mm bullets can be afforded by an equivalent of 15mm of Rolled Homogeneous Armour (RHA). This might be achieved by bolting 10-12mm of RHA to the outer faces of the existing bridge structure. If armour is added to the bridge there will be a risk of spall,(fragments of plating), from the armour if it is attacked by a more severe threat than the protection is designed to defeat. This can be mitigated using a spall lineras the innermost layer of material inside the bridge. Overall the additional weight of armouring the bridge of a vessel in this way could amount to between 4-6 tonnes and cost between 25,000 and 40,000 to purchase.
The longer term measures may be considered at the design stage of a new build vessel. Cost implications could be mitigated to some extent by incorporating the hardening of the bridge structure as a shipyard standard cost, rather than an owners requested additional requirement. Weight considerations can also be mitigated by use of Kevlaror similar, however while weight is considerably reduced, cost is proportionally increased.
Conclusions
The results of the study clearly demonstrate the following:
- The risk of a fatality in a vessel where the bridge windows have been protected is considerably reduced (in percentage terms) compared to a vessel with no bridge protection.
- The additional risk reduction achieved by hardening the steelwork is negligible, with the exception of the 12.7mm DhSk heavy machine gun.
An attack using an RPG would be expected to cause increased vulnerability. Intests conducted although RPG fire was able to penetrate the armoured bridge, the windows did not shatter inwards causing fragmentation. Secondary fragmentation was the dominating result. The absence or reduction of primary fragmentation gives a lower probability of a fatality. In order to provide effective crew protection from an RPG attack to the bridge, the fitting of RPG netting or double chain link fences is recommended. This provides a barrier preventing the ordnance striking and detonating on the bridge structure, mitigating the risk of fragmentation injuries to the crew.
Recommendations
The results of this study enable recommendations for both existing vessels and vessels to be built.
Recommendations for Existing Ships
- In modifying an existing vessel, the simplest and most effective protection for the bridge is the installation of shatterproof film to the windows. As a guide it would cost in the region of 2,000 to protect the bridge windows of a single vessel.
- The conclusions of the report only show a marginal improvement of protection if the superstructure bulkheads are hardened. Bolting on of 10mm RHA plating to a ballistic standard that would defeat an AK47, (EU Standard 1522 – FB6) would cost in the region of 25,000 – 40,000, and would incur additional weight of approximately 4-6 tonnes.
- Full protection may not be cost effective. However a partial installation, carefully sited may be beneficial, for example on the bridge wing area where it may provide additional protection from incoming projectiles on the beam of the vessel.
- Existing vessels may provide additional protection against an RPG by fitting either proprietary net technology around the outer edges of the superstructure deck, or by fitting double chain link fencing.
- The former is available from the majority of defence manufacturing companies but is expensive. The latter is effective and cheap to install.
Recommendations for New Build Tonnage
- For a new build vessel the following protective measures should be considered at the design stage.
- Bridge windows, bridge wing doors and all accommodation portholes could be fitted with windows that are protected to EU Standard EN 1063 BR6.
- The bridge superstructure could be designed to provide ballistic resistance standards offering protection against rounds up to 7.62mm x 39 (EU Standard 1522FB6). This would involve 15mm HA in lieu of the existing 7mm mild steel.
- Should weight considerations make this undesirable then Kevlar could be used, but weight savings would be countered by additional cost.
- Bridge wings and the bridge front could be constructed with the ability to ensure that fitting of either RPG netting or double chain link fence is made simple and portable.
Learn more details by reading the study issued by OCIMP on Bridge Vulnerability (please click at image below)
EXPLORE MORE BY READING OCIMF REPORT HERE
